ILLINOIS LIBRARY URBANA-CHAMPAIG r''RAL HIST. SURV FIELD Botany A Systematic Study of Flourensia (Asteraceae, Heliantheae) Michael O. Dillon December 31, 1984 Pub! i PUBLISHED BY i i OF FIELDIANA Botany NEW SERIES, NO. 16 A Systematic Study of Flourensia (Asteraceae, Heliantheae) Michael O. Dillon Assistant Curator Department of Botany Field Museum of Natural History Chicago, Illinois 60605-2496 Accepted for publication April 18, 1984 December 31, 1984 Publication 1357 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1 984 Field Museum of Natural History Library of Congress Catalog Card Number: 84-81690 ISSN 00 15-0746 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents ABSTRACT 1 ACKNOWLEDGMENTS 1 INTRODUCTION 1 TAXONOMIC HISTORY 3 CYTOLOGICAL STUDIES 3 MORPHOLOGY 4 GENERIC RELATIONSHIPS 5 SPECIES RELATIONSHIPS 6 TAXONOMIC TREATMENT 8 Key to Species of Flourensia 9 Doubtful and Excluded Taxa 63 LITERATURE CITED 64 INDEX OF LATIN AND COMMON NAMES . 66 List of Illustrations 1 . Distribution of the genus Flourensia . . 2 2. Species relationships among Flourensia species 6 3. Flourensia laurifolia 11 4. Flourensia retinophylla 13 5. Distribution of Flourensia cernua 14 6. Flourensia dentata 16 7. Flourensia ilicifolia 17 8. Flourensia solitaria 18 9. Distribution of Flourensia dentata, F. ilicifolia, F. laurifolia, F. retinophylla, and F. solitaria 19 10. Flourensia microphylla 21 1 1 . Flourensia collodes 23 1 2. Flourensia glutinosa 24 1 3. Flourensia cernua, F. cernua x F. resi- nosa, and F. resinosa 25 1 4. Distribution of Flourensia collodes, F. glutinosa, and F. resinosa 26 15. Flourensia monticola 28 16. Flourensia pulcherrima 29 1 7. Flourensia pringlei 31 18. Distribution of Flourensia microphylla. F. monticola, F. pringlei, and F. pul- cherrima 32 19. Flourensia thurifera 33 20. Distribution of Flourensia thurifera ... 34 21. Flourensia macrophylla 36 22. Flourensia angustifolia 37 23. Flourensia peruviana 39 24. Flourensia polycephala 40 25. Flourensia heterolepis 41 26. Distribution of Flourensia angustifolia, F. fiebrigii, F. heterolepis, F. macrophyl- la, F. peruviana, and F. polycephala ... 42 27. Flourensia suffrutescens 43 28. Flourensia macroligulata 45 29. Flourensia tortuosa 46 30. Distribution of Flourensia blakeana, F. hirta, F. leptopoda, F. macroligulata, F. suffrutescens, and F. tortuosa 47 3 1 . Flourensia oolepis 49 32. Flourensia fiebrigii 50 33. Flourensia blakeana 52 34. Flourensia hirta 53 35. Flourensia niederleinii 55 36. Flourensia riparia 57 37. Flourensia campestris 58 38. Distribution of Flourensia campestris, F. niederleinii, F. oolepis, and F. riparia 59 39. Flourensia leptopoda 60 40. Flourensia hirtissima 61 41. Distribution of Flourensia hirtissima . 62 List of Tables Morphological comparison of Flourensia and Encelia 5 Distinguishing characteristics of Flouren- sia cernua, F. resinosa, and a putative hybrid 27 in A Systematic Study of Flourensia (Asteraceae, Heliantheae) Abstract Flourensia DC. (Asteraceae, Heliantheae) is composed of glutinous subshrubs, shrubs, and small trees occurring primarily in arid habitats in the American subtropics. The genus has an am- phitropical disjunct distribution, with 13 North American and 1 8 South American species. Exten- sive field studies were conducted throughout the range of the genus. Morphological, cytological, and phytochemical studies were utilized in determin- ing generic and species relationships. Descrip- tions, illustrations, distribution maps, and a key to species are presented. [Key words: Flourensia, Asteraceae, morphology, cytology, amphitropical disjunct distribution, monograph.] Acknowledgments I am indebted to Prof. Billie L. Turner who originally suggested the problem and under whose direction the present study was conducted. I also gratefully acknowledge Drs. William G. D'Arcy and Marshall C. Johnston for providing Latin de- scriptions for new species. I thank the following South American botanists for their generous hos- pitality: Drs. A. B. Andrada, Luis Ariza E., Angel L. Cabrera, Ramon Ferreyra, Armando T. Hun- ziker, Juan H. Hunziker, P. Legname, Ricardo Luti, Oscar Tovar, and Frederico Vervoorst. I thank the following people for their companionship on col- lecting trips and/or constructive criticism of the present study: John Bacon, Kathy Baker, Fernan- do Chiang C., Imre Eifert, Ronald L. Hartman, James Henrickson, Mitzi Reynolds, Alfred Rich- ardson, Eloy Rodriquez, and Thomas Wendt. I thank Drs. Vicki A. Funk and John L. Strother for critically reading the manuscript during the review process. Illustrations were prepared by Ste- ven Chase, Felicia Bond, Jane Fulkerson, Eliza- beth Liebman, Z. Jastrzebski, Marlene Werner, and Yevon L. Wilson. Last, but not least, I thank my wife, Diane, for her patience and help in proof- reading this manuscript. Collecting trips were supported, in part, by the following institutions: National Science Founda- tion (GB-37006), The Society of Sigma Xi, and the University of Texas Graduate School. The following herbaria have lent specimens for this study, and their help is acknowledged: A, ARIZ, ASU, BM, CORD, ENCB, F, GH, GOET, HUT, LIL, LL, LP, MEXU, MICH, MO, MSC, NY, SD, SI, TEX, UC, US, USM. The symbols used are those of Holmgren et al. (1981) and are used as such throughout the paper. Introduction As treated in this study,1 Flourensia is com- posed of glutinous subshrubs, shrubs, and small trees occurring mostly in drier, elevated regions of North and South America. The genus has an am- phitropical distribution (fig. 1), with 13 North American taxa, primarily Mexican (of which two, F. cernua and F. pringlei, enter the southwestern United States), and 18 South American taxa as- sociated with the Andean Cordillera of Peru, Bo- livia, Chile, and Argentina. Since the revision of Flourensia by Blake (1921), eight new species have been described, four from 1 Based on a doctoral dissertation submitted to the Graduate School of the University of Texas at Austin. DILLON: SYSTEMATIC STUDY OF FLOURENSIA —20 —10 — 0 — 10 —20 —30 —40 FIG. 1 . Distribution of the genus Flourensia. north-central Mexico, two from Argentina, and these reasons, a re-examination of the genus was two from Peru. Many unidentified collections have desirable. been added to herbaria over the last 60 years. For In connection with the present study, extensive FIELDIANA: BOTANY field collections and ecological observations were made throughout the range of the genus in North and South America. Approximately 1,500 her- barium specimens were examined from the major herbaria of North and South America. In attempt- ing to establish species relationships, data were used from morphological, cytological, ecological, and phytochemical investigations. Taxonomic History Flourensia was erected by DeCandolle ( 1 836) to include four species: two Mexican discoid taxa, F. laurifolia and F. cernua, and a radiate group in Chile composed of F. thurifera, which was origi- nally described by Molina (1 782) as a Helianthns, and F. corymbosa. Bentham (1873) submerged the genus under He- lianthus, stating that Flourensia thurifera, F. cer- nua, and F. laurifolia do not differ significantly from Helianthus, other than having villous ach- enes and resinous leaves. He removed F. corym- bosa to Viguiera due to the presence of well-de- veloped squamellae between the pappus awns. Gray (1873) treated Flourensia as distinct from Helianthus and agreed with Bentham in the place- ment of F. corymbosa in Viguiera. In 1879, Gray described Encelia microphylla from north-central Mexico and stated, "[It] has shrubby stems, foliage not unlike that of Flourensia cernua, and the re- lationship of the two is apparent." Later (1883), Gray suggested that the discoid taxa (i.e., F. cer- nua, F. laurifolia) were typical for Flourensia and that the radiate F. thurifera might be best treated as a section under Cassini's Diomedia. Gray in- correctly attributed the authorship of Diomedia to Bertero and Colla. Baillon (1886) submerged Flourensia, Wyethia, Tithonia, Diomedia, and Viguiera into Helian- thus, thus creating a highly variable and, I pre- sume, polyphyletic assemblage. Hoffmann (1894) reinstated Flourensia as a distinct genus, and it has been retained by nearly all subsequent authors. Blake (1913) began work on the genus during a revision of Encelia, at which time he transferred six radiate taxa from Encelia (E. collodes, E. glu- tinosa, E. microphylla, E. oblonga, E. resinosa, and E. suffrutescens) to Flourensia, and also de- scribed F. retinophylla from Coahuila, Mexico. In 1916, he described two new South American species, F. macrophylla and F. fiebrigii. In 1918, during a revision of Viguiera, Blake established F. heterolepis and transferred several taxa previously included in Flourensia (F. atacamensis, F. cor- ymbosa var. araucana, F. c. var. lanceolata, F. gayana, F. hispida, and F. navarri) to Viguiera. Blake (1921) published a revision of Flourensia, in which five new species from Argentina were described: F. hirta, F. leptopoda, F. niederleinii, F. oolepis, and F. polyclada. He subsequently de- scribed three additional species: F. hirtissima from Argentina in 1 924, F. dentata from Mexico in 1 935, and F. solitaria from Mexico in 1950. In 1 960, Seeligmann described F. macroligulata from northern Argentina. The last additions to the genus have been two species from north-central Mexico, F. pulcherrima and F. monticola (Dillon, 1976), and three species from South America, F. blakeana from Argentina and F. polycephala and F. peruviana from Peru (Dillon, 1981). Cytological Studies Prior to the present study, only four chromo- some counts for Flourensia were reported in the literature. Turner & Johnston (1961) reported meiotic counts of n = 18 pairs for the Mexican species F. laurifolia and F. resinosa, Di Fulvio (1977) reported a meiotic count of n = 18 pairs for F. campestris of Argentina, and Strother (1983) reported a meiotic count of n = 18 for the Mexican species F. collodes. Dr. Michael Powell (pers. comm.) found n = 27 univalents in one collection of F. cernua from Coahuila, Mexico. In the present study, counts were made in 28 populations rep- resenting 14 species, 10 of which are South Amer- ican, and four, North American (Dillon, 1976). Vouchers are on deposit at TEX and marked with an asterisk (*) in citations of representative species. Field-collected bud material was fixed in mod- ified Carney's solution (chloroform: absolute eth- anol: glacial acetic acid, 4:3:1, v/v/v), and chro- mosome squashes were stained in aceto-carmine. A mitotic chromosome count of 2n = 36 for Flourensia thurifera was determined from root tips of laboratory-germinated achenes. Flourensia appears to be monobasic with x = 1 8. Chromosome counts are known for only 1 7 of the species, but all counts to date have been n = 18. This relatively high base number is character- istic of other genera considered most closely re- lated to Flourensia (see Generic Relationships sec- tion). As noted, a meiotic count of 27 univalents has DILLON: SYSTEMATIC STUDY OF FLOURENSIA been reported for Flourensia cernua. However, pollen fertility of the voucher was determined as 99% (more than 500 grains examined). Thus, it appears that nonchiasmatic meiotic figures do not adversely affect fertility. Because none of the other populations of F. cernua sampled throughout its range exhibited univalents, it is assumed that such irregularities are relatively rare. Morphology Species of Flourensia are delineated through combinations of qualitative and quantitative char- acters. The following section explains how various measurements (reported in the descriptions) were made and the extent of their utility in the circum- scription of taxa. Leaves All leaf measurements are for the blades only. Petiole measurements are given separately. Leaf size, shape, and degree of denticulation tend to be quite uniform within most taxa. This usually al- lows species to be recognized in the sterile con- dition. Leaves of various species exhibit characteristics that presumably confer drought resistance and al- low them to inhabit arid environments. Well-de- veloped cuticles and resinous exudates are usually present on leaf surfaces. Many species are drought- deciduous, with the extent of leaf loss dependent upon the length and severity of drought periods. In Flourensia thurifera of central Chile, the only species to be studied in detail, the leaves gradually dry up as drought progresses until there are only a few terminal leaves remaining (Mooney & Kum- merow, 1971). Capitulescence In most species of Flourensia, the capitula are arranged into determinate, secondary cymes. These are in turn occasionally arranged into panicles or racemes. Solitary capitula, terminating stems or branchlets, are most common among the many- rayed taxa, but may also be found in discoid species (e.g., F. solitarid). Capitula The height of the capitula was measured from the base of the involucre to the top of the disc florets. The width measurements exclude the ray florets and represent the width of the involucre only. Capitular size is somewhat variable within and between individuals; however, some species with similar leaf morphologies can be distin- guished by their capitular size. The capitula can be grouped into two categories based upon the presence or absence of ray florets: ( 1 ) Discoid taxa possess capitula with only tubular, 5-lobed corollas. This developmental suppression of ray florets has occurred within six species, all of North America. The loss of rays in usually ra- diate genera is not uncommon among many mem- bers of the Heliantheae. Encelia, Viguiera, En- celiopsis, and Geraea, among others, all possess discoid taxa, while their members are predomi- nately radiate. Obviously such loss is not selec- tively disadvantageous; discoid Flourensia have been quite successful in occupying a wide range of xeric environments (e.g., F. cernua). (2) The radiate taxa possess capitula with typical disc florets surrounded by ray florets with well- developed ligules. Within this category, two ad- ditional groups can be separated on the basis of the number of ray florets: In one line, an actino- morphic pattern is presented where members have more than eight (8) rays, usually a Fibonacci num- ber (i.e., 13, 21, etc.). In the other, a pleiomorphic or numerate pattern is presented where members have five (5) or eight (8) rays, but occasionally as many as 10 or as few as four (4). Specialization in the number of ray florets is considered to be a response to pollinator selection, for these taxa dis- play patterns that mimic pleiomorphic "true" flowers (Leppik, 1970). Phyllaries Involucres are quite diagnostic, with phyllary size, shape, and vestiture being uniform within most species. The phyllaries are normally imbri- cate in two to five series and less often equal or subequal. In a few species, e.g., Flourensia prin- glei, the outer phyllaries are long and overtop the inner ones. The phyllaries of each series are usually differentiated in size and shape. Most are herba- ceous, or only basally indurate, and tend to be- come reflexed at maturity. One exception is F. solitaria, which has phyllaries that are mostly in- durate, persistent, and remain erect at maturity. Achenes The achenes are usually obconical, laterally compressed, thickened, and sericeous, at least on FIELDIANA: BOTANY the margins. They range from 6 to 12 mm long, and considerable variability can be found among members of the same population. All have a pap- pus of two (rarely three or four) aristiform, setose awns arising from the thickened margins. The only exception is F. solitaria, which has nearly terete achenes that lack a pappus and obvious pubes- cence. Flourensia taxa lack paleaceous squamellae such as occur in many Viguiera and Helianthus. How- ever, the bases of the awns can be strongly am- pliate and deeply lacerate and often united to form a lacerate corona between the awns (e.g., F. ilici- folia, F. collodes, F. thurifera, F. oolepis). This pappus condition is also exhibited by some Vi- guieras. Generic Relationships While all authors since Hoffmann (1894) have recognized Flourensia as a distinct genus, there has been little agreement upon its subtribal place- ment. Hoffmann (1894) placed Flourensia within Verbesininae, between Lipochaeta and Spilanthes (s.l.). These two genera are here considered quite distant from Flourensia. Blake (1913, p. 350) considered the following genera to be related and provided a key for their discrimination: Flourensia, Helianthus, Viguiera, Simsia, Encelia, Enceliopsis, Geraea, Helianthel- la, and Verbesina. In this revision of Flourensia, Blake (1 92 1) made no mention of possible generic relatives other than to point out the differences between it and Helianthus and Viguiera. Stuessy (1977) included Flourensia within He- lianthinae, based on the following characteristics: (1) alternate-leaved shrubs, (2) neuter ray florets and fertile disc florets, (3) conduplicate paleae, and (4) convex receptacles. Robinson (1981) re-delineated the subtribes of Heliantheae and placed Flourensia within his "Encelia group" in Ecliptinae (a prior name for Verbesininae). This group included Encelia, En- celiopsis, Flourensia, Geraea, and Phoebanthus. During my examination of the genera that had been considered close relatives of Flourensia, the only genus that could be considered related is En- celia. The morphological characteristics that dis- tinguish these two genera are summarized in Ta- ble 1. In addition to these morphological differences, the two have quite different eco-geographical dis- tributions. The center of diversity of Flourensia TABLE 1 . Morphological comparison of Flourensia and Encelia. Character Flourensia Encelia Habit Subshrubs, Scapose or shrubs, and small shrubs small trees Leaves Usually subgla- Usually canes- brous and resi- cent resin not nous obvious Ray florets Bi-denticulate Tri-denticulate Disc florets Yellow Yellow or pur- ple Paleae Coriaceous or in- Soft or scarious durate Achenes Thickened to Compressed, plump, seri- very flat, vil- ceous (at least lous on mar- margins) gins, faces usually gla- brous Pappus 2-3(-4) aristiform Absent, or rare- awns ly of 2 awns Style branch- Broadly to nar- Short obtuse ap- es rowly acute ap- pendages pendages in North America is within the Chihuahuan Desert region of central Mexico and in South America in the Andean Cordillera. In contrast, Encelia has its center of diversity in arid regions of the western United States and adjacent Baja California, Mex- ico (chiefly the Sonoran Desert). Two species occur in scattered coastal localities in Chile and Peru. One species is endemic to the Galapagos Islands. This suggests the quite different edaphic and phys- iological requirements of these genera. Flourensia has a probable base chromosome number of x = 18, all counts thus far being n = 18 (see Cytological Studies section). Of the genera considered close to Flourensia, only Encelia (n = 1 7, 1 8), Enceliopsis (n = 1 7, 1 8), and Geraea (n = 18) share this number. The last two genera are morphologically and geographically distinct from Flourensia. Phytochemical data have been useful in the de- lineation of generic groupings within certain sub- tribes of Asteraceae (Seaman, 1982). Although a thorough survey is lacking, present data indicate that Flourensia elaborates a unique array of ses- quiterpenes and triterpenes (Kingston et al., 1975; Estrada et al., 1965; M. Aregullin, pers. comm.), polyacetylenes (Bohlmann, pers. comm.), and fla- vonoids (Dillon etal., 19 76; Dillon &Mabry, 1977; Rao et al., 1970). Further analysis of taxa within this genus and elsewhere within the tribe will be necessary before emphasis can be placed upon these data. DILLON: SYSTEMATIC STUDY OF FLOURENSIA FIG. 2. Species relationships among Flourensia species. Key to abbreviations: ang = F. angustifolia; bla = F. blakeana; cam = F. campestris; cer = F. cernua; col = F. collodes; den = F. dentata; fie = F. fiebrigii; glu = F. glu- tinosa; het = F. heterolepis; hir = F. hirta; hts = F. hirtissima; ili = F. ilicifolia; lau = F. laurifolia; lep = F. leptopoda; mic = F. microphylla; mli = F. macroligulata; mon = F. monticola; mph = F. macrophylla; nie = F. niederleinii; ool = F. oolepis; per = F. peruviana; pol = F. polycephala; pri = F. pringlei; pul = F. pulcherrima; res = F. resinosa; ret = F. retinophylla; rip = F. riparia; sol = F. solitaria; suf = F. suffrutescens; tor = F. tortuosa; thu = F. thurifera. An examination of available data indicates that Flourensia is a natural assemblage of taxa that lacks close generic relatives, with the exception of Encelia. While subtribal classification within He- liantheae is being debated, the position of Flour- ensia near the aforementioned genus is clear. Species Relationships Efforts to establish species relationships within Flourensia have been made more difficult by the parallel development of various character states in both North and South American taxa. In this study, species groupings have been made primarily through the comparison of exomorphic features. Capitular morphology, including the size and shape of phyllaries, and the presence and number of ray florets were considered most important in the de- lineation of groups. Secondarily, characters such as leaf size and shape, pubescence, capitulescence type, ecological preferences, and geographical lo- cality were considered. In addition, data from phy- tochemical studies were helpful in inferring affin- ities between various taxa. The results of the phytochemical studies will be presented in a future publication. Figure 2 represents the interspecific relation- ships within the genus as suggested by these data. The presumed relationships within North Amer- ican taxa will be discussed first, followed by those of South American taxa. Finally, consideration will be given to the possible origin of the amphitropical distribution of the genus. Two groups can be distinguished in North FIELDIANA: BOTANY America by the presence or absence of ray florets. This character is constant within any given species. All the radiate species occur at higher elevations, usually in arid, montane sites. Flourensia monti- cola, F. pulcherrima, and F. pringlei form one line within the radiate taxa. They possess large capit- ula, usually solitary at the tips of branchlets, and have 1 3-2 1 ray florets. Their involucres are com- posed of large, foliaceous phyllaries that equal or overtop the disc. Flourensia resinosa, F. collodes, and F. gluti- nosa form another line, which is characterized by possessing small capitula with 8-13(-16) ray flo- rets and cymose capitulescences. Their involucres are composed of small indurate phyllaries that tend to be imbricate and not overtopping the disc. Flourensia microphylla represents a highly re- duced radiate type, which shares characteristics with the discoid taxa (e.g., reduced habit and small leaves). The relationships of this rare species are unclear at present; however, capitular morphology suggests ties with F. resinosa. The six discoid species are considered to form a monophyletic group derived from now extinct radiate stock resembling Flourensia collodes or F. glutinosa. All discoid taxa occur within the Chi- huahuan Desert Region, with the exception of F. laurifolia of the Tamaulipan thorn scrub. Flour- ensia laurifolia, F. retinophylla, and F. cernua form one line, which appears to be a reduction series in response to increasing aridity in their respective environments. Flourensia solitaria, F. ilicifolia, and F. dentata are each rather isolated, primitive derivatives from the F. cernua line. Flourensia ilicifolia and F. dentata are the only North Amer- ican taxa that lack entire leaves. Three weakly differentiated lines can be recog- nized among the South American taxa. Flourensia macrophylla, F. angustifolia, F. peruviana, and F. polycephala are all distributed within the Andes of northern to southern Peru. They share similar capitulescences, capitular morphologies (8-13 ray florets), and ecological preferences. Flourensia thurifera of central Chile is clearly related to this line through F. macrophylla; both have similar leaves and involucres. Flourensia suffrutescens, F. tortuosa, F. macro- ligulata, and F. oolepis form a line characterized by large capitula with broad phyllaries and 1 3-2 1 ray florets. Flourensia heterolepis appears transi- tional between this group and the last and is most closely related to F. polycephala. The remaining eight species are all closely re- lated and share many characters, including similar capitulescences and capitular morphologies. These taxa are distributed from southern Bolivia to southern Argentina and share similar ecological preferences. Flourensia riparia, F. campestris, F. leptopoda, F. niederleinii, F. hirta, F.fiebrigii, and F. blakeana all exhibit a trend toward fewer ray florets, with the majority of species possessing 5- 8 ray florets. Flourensia hirtissima, with solitary capitula, most closely approaches some individ- uals of F. fiebrigii and is probably a product from that line. This lineage is clearly related to the pre- vious one, but tends to occupy more arid envi- ronments at lower elevations. Flourensia riparia seems basal within the line and shares habit, foliar, and capitular characteristics with F. heterolepis. The two hemispheres contain comparable num- bers of taxa, 1 3 North American and 1 8 South American. No single species is disjunct between continents. Despite their mutual cohesion, there are parallel trends among the species on both con- tinents, including similar growth forms, leaf shapes, capitula, and achenes. Flourensia can be classified as an example of a generic allodisj unction (Turner, 1972), for the taxa concerned are widely separated spatially and appear to have been derived through phyletic divergence from populations now extinct. How did Flourensia attain its present amphi- tropical distribution? There is a gap in its range of approximately 1,500 km from Chiapas, Mexico (ca. 16°N lat.), to northern Peru (ca. 8°S lat.). Geo- morphic evidence indicates that the continuous land bridge in Middle America is of recent origin (Raven & Axelrod, 1975) and has probably not acted as a corridor for widespread migrations of xeric elements between North and South America. The opportunity for this has been greater in recent times than at any period in the past. The north- ernmost distribution of Flourensia in South Amer- ica is just south of the Huancabamba Deflection in northern Peru. Simpson (1975) has pointed out that this area is lower than many inter-Andean valleys and that it has acted as a significant barrier to north-south land migration since early times. If Flourensia had been previously more wide- spread within the tropics, one would expect to find the genus represented in appropriate habitats in deep valleys and basins in north-central Guate- mala and central Honduras. These areas, due to rain-shadow effects, receive relatively scant pre- cipitation and exhibit dry tropical scrub vegeta- tion. The genus is also absent in dry Andean val- leys from western Venezuela to Ecuador. Considering this absence of the genus in Middle America and northern South America, the exis- DILLON: SYSTEMATIC STUDY OF FLOURENSIA tence of a widespread, more or less continuous, tropical progenitor seems unlikely. Rather, the ge- nus probably reached its present distribution through long-distance dispersal of achenes, per- haps by birds. Cruden ( 1 966) has pointed out that, for many groups of taxa, transport of propagules by birds is the only likely mode of long-distance dispersal. Carlquist (1981) stated, "External at- tachment of seeds and fruits to birds has also played an appreciable role in the dispersal of flora to Ha- waii." In particular, Gillet & Kim (1970) have shown that the large array of endemic Bidens species in the Hawaiian Islands has evolved from a single introduction from North America during the past five million years. Evidence also indicates that transport of seeds and fruits on or in birds can account for many of the North-South Amer- ican desert disjunctions (Carlquist, 1983; Solbrig, 1 972). Though it may seem unreasonable to evoke long-distance dispersal to explain present-day dis- junctions (especially in taxa that today are not actively dispersed long distances), this hypothesis remains the best explanation for many of these unusual distributions. As Carlquist (1981) pointed out, it is unfortunate that one must "use evidence that is circumstantial, indirect, and subjective and therefore vulnerable." That Flourensia is a long-time occupant of both continents may be deduced from ecological con- siderations. Species of the genus are often the sole dominants of the communities that they occupy. In fact, when dominant, they occupy different kinds of communities on the two continents. For ex- ample, in North America, F. cernua tends to dom- inate flats with deep soils (Muller, 1 940), while F. tortuosa dominates dry grassy bajadas in northern Argentina. The dominant position of Flourensia in these totally different ecosystems must reflect long-time physiological selection for their respec- tive roles. Axelrod (1970) and Williams (1975) have ar- gued that the present extensive regions of arid en- vironment are of Pliocene-Pleistocene origin and were developing simultaneously in both hemi- spheres. Given the present amount of morpho- logical divergence within the species of each con- tinent, and their eco-geographical distribution, it appears that Flourensia was represented on both continents prior to Pleistocene time. The various taxa have almost certainly evolved independently on each continent in response to changing con- ditions since that time. Flourensia possibly had its origin in North America. This conjecture is plausible simply be- cause there is considerably greater morphological divergence among the North American taxa, and North America has been postulated as the origin for a great number of genera of Heliantheae, in- cluding all those thought to possess some affinities with Flourensia (Bentham, 1873; Turner, 1977). Although there are more species of Flourensia in South America, this is a reflection of more re- cent events. It appears likely that many of the South American species have radiated into geo- graphical and ecological areas postulated to have undergone a series of humid-arid cycles during the Quaternary which drastically and repeatedly al- tered vegetation patterns (Simpson, 1975). This area undoubtedly represents a region of secondary radiation. Taxonomic Treatment Flourensia DC., Prodr. 5: 592. 1836. LECTO- TYPE (Blake, 1921): Flourensia laurifolia DC. Subshrubs, shrubs, or small trees; trunks and stems with well-developed bark, brown to black; branchlets usually glandular, resinous, aromatic, glabrate to pilose-lanate. Leaves simple, alternate, linear-lanceolate to oval, pinnatinerved, midrib prominent on abaxial surface, finely prominulous- reticulate, mostly coriaceous, resinous, viscid, vernicose, the margins entire to dentate, often strigillose. Capitulescences solitary to cymose-pa- niculate; peduncles to 20 cm long, often bracteate. Capitula discoid or radiate, 6-20 mm high, 5-20 mm wide; involucres cylindrical, campanulate, hemispheric, or turbinate; phyllaries 2-5 -seriate, imbricate, graduate, equal, or the outer overtop- ping the disc, linear-lanceolate to rhombic-ovate, herbaceous to indurate, glandular, resinous, gla- brous to hirsute; paleae usually oblanceolate, em- bracing (and deciduous with) achenes, carinate, scarious to coriaceous, apically attenuate to trun- cate or cucullate, often mucronate, glandular, re- sinous, rarely hispidulous; receptacles flat to con- vex; ray florets 5-21 (or absent), neuter (rarely styliferous), sterile, the ligules yellow, oval to ob- long, 7-50 mm long, apically bifid, the tube gla- brous to sericeous; disc florets 10-1 50, the corollas yellow, cylindric-campanulate to salverform, 4-8 mm long, the tube (0.5-) 1-1.5 (-2) mm long, 5-lobed, the lobes lance-triangular to deltoid, glan- dular, resinous, rarely spiculiferous; anthers ca. 4 mm long, the terminal appendages ovate, basally FIELDIANA: BOTANY obtuse; style branches slender, recurved, the ap- dular, resinous, often finely striate; pappus of 2 pendages broadly acute to attenuate, dorsally his- (rarely 3 or 4) awns, rarely absent, persistent or pidulous. Achenes laterally compressed to thick- disarticulating, ciliolate, the bases ampliate, lac- ened, rarely terete, oblong to obconical or cuneate, erate; true squamellae absent. Base chromosome 4- 1 2 mm long, glabrous to villous-sericeous, glan- number: x = 1 8. Key to Species of Flourensia 1 . Plants of North America (Mexico, southwestern United States) 2 2. Capitula discoid 3 3. Leaves entire 4 4. Leaves 1.5-13.5 cm long, 2-6 cm wide; petioles 5-10 mm long 1. F. laurifolia 4. Leaves 1-5 cm long, 0.5-1.5 cm wide; petioles 1-4 mm long 5 5. Achenes obscurely puberulent (appearing glabrous), pappus absent; phyllaries ca. 5-seriate 6. F. solitaria 5. Achenes villous-sericeous, pappus of 2, persistent, aristiform awns; phyllaries ca. 2-seriate 6 6. Capitulescences racemose-cymes; leaves narrowly elliptic to lanceolate 2. F. retinophylla 6. Capitulescences spiciform; leaves elliptic to ovate 3. F. cernua 3. Leaves dentate or iliciform 7 7. Leaves rhombic-ovate, the margins with 3-6, stiff, mucronate teeth; corolla lobes ca. 2.5 mm long 5. F. ilicifolia 7. Leaves elliptic-ovate, the marginal teeth lacking mucros; corolla lobes ca. 1 mm long . . . 4. F. dentata 2. Capitula radiate 8 8. Mid-stem leaves not exceeding 2.5 cm long, 5-10 mm wide 7. F. microphylla 8. Mid-stem leaves 3.5-14 cm long, 2-7 cm wide 9 9. Suffruticose, stems unbranched, to 0.5 m tall; ray florets 13-21 13. F. pringlei 9. Shrub, stems much-branched, usually over 1 m tall; ray florets 7-13 (-16) 10 10. Capitulescences cymose-paniculate, 5-20-headed; ray florets 7-10 . . . 9. F. glutinosa 10. Capitulescences cymose to solitary, 1-5-headed; ray florets 10-13 (-16) 11 1 1 . Phyllaries 2-seriate, 1 8-20 mm long, the outer overtopping the disc 12. F. pulcherrima 11. Phyllaries 3-4-seriate, 4-10 mm long, imbricate to subequal 12 12. Cauline leaves 3.5-7 cm long, 8-18 mm wide; petioles 2-4 mm long; ray florets ca. 10 10. F. resinosa 12. Cauline leaves 6-14 cm long, 2-6.5 cm wide; petioles 7-22 mm long; ray florets ca. 1 3 13 13. Leaves ovate, basally oblique, rounded; Capitulescences cymose-pani- culate, 4-5-headed 8. F. collodes 13. Leaves lanceolate to obovate, basally attenuate; Capitulescences solitary 1 1 . F. monticola 1. Plants of South America (Peru, Chile, Bolivia, Argentina) 14 14. Leaf margins deeply to shallowly repand-dentate to cuspidate-denticulate 15 1 5. Capitula 1-2 cm high, 14-25 mm wide; ray florets 12-16 16 16. Leaves ovate to oblong-elliptic, the margins repand-dentate with 4-10 pairs of triangular teeth; Capitulescences cymose, 4-8-headed; peduncles 3-13 cm long . . 14. F. thurifera 16. Leaves elliptic-lanceolate to elliptic, the margins with 2-3 pairs of teeth distally; cap- itulescences solitary or weakly cymose, 2-3-headed; peduncles 4-6 cm long 23. F. oolepis 15. Capitula 8-12 mm high, 5-15 mm wide; ray florets 5-8 17 DILLON: SYSTEMATIC STUDY OF FLOURENSIA 17. Leaves oval to oblong or lanceolate, the margins shallowly denticulate-cuspidate; pet- ioles 2-5 mm long; capitula 10-12 mm high, 8-15 mm wide 18 18. Leaves oval to oblong-oval, apice obtuse to subobtuse 15. F. macrophylla 18. Leaves lanceolate to narrowly-elliptic, apices acute 16. F. angustifolia 1 7. Leaves lanceolate to rhombic-ovate or ovate, the margins deeply and irregularly repand- dentate or with slight denticulations; petioles (2-) 5-13 mm long; capitula ca. 8 mm high, 5-7 mm wide 19 19. Capitulescences weakly cymose, 2-4-headed 30. F. leptopoda 19. Capitulescences cymose-paniculate, 5-15-headed 29. F. campestris 14. Leaf margins strictly entire 20 20. Subshrubs to 20 cm tall; largest leaves narrowly linear-lanceolate to linear-oblanceolate, 2- 4mm wide (some individuals of F. fiebrigii and F. suffrutescens have reduced habits, but leaves 7-1 8 mm wide) 3 1 . F. hirtissima 20. Shrubs greater than 20 cm tall; leaves elliptic to lanceolate or ovate, the largest leaves 5-60 cm wide 21 2 1 . Phyllaries greater than 2 mm wide (at least the inner); ray florets (9-) 1 0-2 1 22 22. Capitulescences weakly cymose to cymose-paniculate (rarely solitary); outer phyl- laries 7-9 mm long, 1-2 mm wide, linear-lanceolate to lanceolate 23 23. Capitulescences cymose-paniculate, 4-8-headed; peduncles mostly 3-5 cm long 18. F. polycephala 23. Capitulescences weakly cymose, 2-5 -headed (occasionally solitary); peduncles mostly 5-8 cm long 1 9. F. heterolepis 22. Capitulescences solitary (rarely weakly cymose); outer phyllaries (5-) 10-22 mm long, 2-7 mm wide, lanceolate-elliptic to ovate 24 24. Leaves narrowly lanceolate to oblong, 8-18 mm wide . . 20. F. suffrutescens 24. Leaves lanceolate to elliptic or oval, 1 5-60 mm wide 25 25. Phyllaries sericeous; ray florets 13-21, the ligules 25-50 mm long 21. F. macroligulata 25. Phyllaries puberulent to glabrous; ray florets ca. 10, the ligules 18-30 mm long 22. F. tortuosa 21. Phyllaries to 2 mm wide; ray florets 5-8 (-10) 26 26. Leaves ovate-lanceolate to ovate, (1 1-) 15-50 mm wide 27 27. Leaves 6-14 cm long, 1 5-50 mm wide 28. F. riparia 27. Leaves 3.5-9 cm long, 1 1-34 mm wide 28 28. Capitulescences cymose, 2-4-headed 27. F. niederleinii 28. Capitulescences cymose-paniculate, 5-15-headed .... 29. F. campestris 26. Leaves narrowly oblong-elliptic to lanceolate or oblanceolate, (3-) 4-14 (-20) mm wide 29 29. Leaves mostly less than 3.5 cm long, narrowly oblong-elliptic; outer phyllaries glabrous 25. F. blakeana 29. Leaves mostly greater than 3.5 cm long, linear-lanceolate to oblanceolate; outer phyllaries strigillose to hirsutulose, rarely glabrescent 30 30. Leaves lanceolate to linear-lanceolate, 5-10 (-12) mm wide; phyllaries 6- 10 mm long, the margins strigillose to hirsutulose; ray florets 5-8 26. F. hirta 30. Leaves lanceolate to oblanceolate, (5-) 7-14 (-20) mm wide; phyllaries 4-6 (-8) mm long; ray florets 7-10 24. F. fiebrigii 1. Flourensia laurifolia DC., Prodr. 5: 592. 1836. 800. 952: I. 4!, BM!, F!, GH!, MO!, NY!). Figures TYPE: Mexico, Tamaulipas, between Victoria 3, 9. ("Vittoria") and Tula, "cerca Las Minces," Nov. 1 830, J. L. Berlandier 2205 (lectotype, chosen Helianthus iaUrifolius (DC.) Benth. & J. D. Hook, ex from two isotypes, G-DC, IDC Microfiche 800. j D. Hook. & A. B. Jackson, Ind. Kew. 1: 1112. 952: I. 3!; isolectotypes, G-DC, IDC Microfiche 1893. 10 FIELDIANA: BOTANY I cm FIG. 3. Flourensia laurifolia (from Dillon & Reynolds 659, F). A, habit; B, capitulum; C, floret. Arborescent shrubs or small trees to 5 m tall; branches gray-brown; branchlets resin-encrusted. Leaves ovate to elliptic-ovate, 5.5-13.5 cm long, 2-6 cm wide, the costae strigillose, otherwise gla- brous, upper surface vernicose, basally cuneate, apically acuminate to attenuate (rarely obtuse), the margins entire; petioles 5-15 mm long, strigillose. Capitulescences cymose-paniculate, 3-7-headed; peduncles 1-4 cm long, bracteate. Capitula dis- coid, 11-18 mm high, 10-15 mm wide; involucres cylindrical to hemispheric; phyllaries 3-4-seriate, imbricate, subherbaceous, ciliolate, the outer lin- ear-lanceolate to lance-ovate, 5-6 mm long, 1-3 mm wide, the inner oblong-ovate to oblong-lan- ceolate, 8-10 mm long, 2-3 mm wide, all apically acute, indurate and reflexed in fruit; paleae oblan- ceolate, ca. 12 mm long, apically obtuse; florets 30-50, the corollas cylindric-campanulate, 6-7 mm long, the tube ca. 2 mm long, the lobes ca. 1.5 mm long. Achenes obconical, 6.5-8 mm long, thick- ened, sericeous; pappus of 2 awns, ca. 5 mm long. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— Septem- ber-December (December-April). DISTRIBUTION AND HABITAT (Fio. 9)— Domi- nant locally on dry, steep, limestone slopes of in- termontane valleys in the Sierra Madre Oriental, from southwestern Tamaulipas, western San Luis Potosi, and northern Hidalgo, Mexico (900-1,600 m). VERNACULAR NAME— Ojancha. REPRESENTATIVE SPECIMENS EXAMINED— MEXICO. Hidalgo: Jacala, Kenoyer839(\Riz, F, MO); dry slopes be- yond Hilo Juanico on road to Pacula, Moore 1802 (GH). DILLON: SYSTEMATIC STUDY OF FLOURENSIA 11 San Luis Potosi: ca. 37 km E of Rioverde, Cronquist 1 1276 (F, GH, NY, us); ca. 15 km NW of Cardenas, along road to Ciudad del Maiz, Cronquist & Villosenor 11743 (F, NY); W of Minas de San Rafael, Moron 10012 (ARIZ, so, uc, us); San Luis Potosi to Tampico, Palmer 1109 (GH); Minas de San Rafael, Purpus 4789 (BM, F, GH, MO, NY, so, us), Pozo de Acuna, Guadalcazar, Rzedowski 686 (ENCB, GH, TEX, us); ca. 5 km W of Santa Catarina, San Nicolar Tolentino, Rzedowski 5729 (ENCB). 1 amau- lipas: ca. 20 mi SW of Victoria, Bacon & Dillon 1713 (F); 1 3 mi S of Victoria, Carlson 2750 (p[2], GH, TEX); Mesa de Llera, Davis s.n. (TEX); 11 mi N of Tropic of Cancer, 20 mi S of Victoria, Dillon & Reynolds 659 (F, MEXU, MO, NY, TEX); ca. 40 mi NE of Tula, Dillon et al. 639 (F, MEXU, MO, TEX); 16 mi S of Victoria, Graham & Johnston 4717* (TEX); near Llera, Kenoyer & Crum 3435 (A); ca. 20 mi S of Victoria, Lowrey et al. s.n. (TEX); 13 mi WSW of Jaumave, Moran 10025 (so); vicinity of Victoria, Palmer 32 (F, GH, MO, NY, us); Tula, Puig 3678 (ENCB); between Jaumave and Victoria, Rozynski 178 (F, NY, uc); La Jolla Ranch, Runyon 1013 (us); valley of Jaumave, Runyon 5453 (TEX); 20 mi S of Ciudad Vic- toria, Smith & Barkley 17 M 165 (F, GH, MSC); Jaumave, Viereck 851 (us); 34 mi S of Victoria, Webster & B reckon 16374 (GH). CULTIVATED UNITED STATES. Tex- as: Houston, nursery, raised from seeds collected at Tamazunchale, San Luis Potosi, Mexico, Lowrys.n. (us); Brownsville, grown from seed collected S of Victoria, Tamaulipas, Mexico, Runyon 2004 (F[2], TEX), Runyon 3544 (BM, TEX). Flourensia laurifolia is readily distinguished by its arborescent habit and large, discoid capitula in cymose panicles. It has shiny, evergreen leaves and fragrant flowers, and has been taken into culti- vation as an ornamental in northeastern Mexico and southern Texas. In the Tamaulipan Thorn Scrub, this species is locally dominant, with populations commonly having many seedlings evident in the understory. Its associates include Acacia, Agave, Celtis, Cor- dia, and Opuntia. 2. Flourensia retinophylla S. F. Blake, Proc. Amer. Acad. Arts 49: 505. 1913. TYPE: Mexico, Coa- huila, Sierra de la Paila, Nov. 1 9 1 0, J. A. Purpus 4728 (holotype, GH!, isotypes, BM!, F!, MO!, NY!, uc!, us!). Figures 4, 9. Shrubs to 3 m tall; stems much-branched, resi- nous, aromatic, the bark brown to black. Leaves narrowly elliptic to lanceolate, 1.5-6 cm long, 4- 1 2 mm wide, upper and lower surfaces glabrous, acute to attenuate at both ends, the margins entire, strigillose; petioles 1-3 mm long. Capitulescences racemose-cymose, 2-6-headed; peduncles 5-20 mm, bracteate. Capitula discoid, 10-13 mm high, 5-10 mm wide; involucres cylindrical to campan- ulate; phyllaries 2-seriate, subequal, subherba- ceous, the outer lanceolate to lance-oblong, api- cally acute, the inner ovate-lanceolate, apically acute to obtuse, 4-6 mm long, 1-2 mm wide; pale- ae oblanceolate, ca. 10 mm long, apically acute to obtuse; florets 10-25, the corolla cylindric-cam- panulate, ca. 6 mm long, the tube ca. 1.5 mm long, the lobes ca. 1 mm long. Achenes obconical to cuneate, ca. 6 mm long, sericeous; pappus of 2 (-3) awns, ca. 3 mm long, basally ampliate. FLOWERING (AND FRUITING) PERIOD— August- November (November-March). DISTRIBUTION AND HABITAT (Fio. 9)— Found on steep, limestone slopes in the mountains sur- rounding the Cuatro Cienegas Basin and Laguna del Key in central Coahuila, Mexico (1,200-2,100 m). VERNACULAR NAME— Yerba de la mula. REPRESENTATIVE SPECIMENS EXAMINED— MEXICO. Coahuila: N foot of Sierra de la Madera, ca. 5 km SE of Rancho Cerro, Chiang et al. 9370 (TEX); Sierra de Paila, ca. 10 mi N of Sta. Marte, Dillon & Hart man 658 (BM, F, GH, HUT, MEXU, MO, NY, TEX); ca. 23 mi NW of Las Delicias, Sierra de Las Delicias, Henrickson 6143 (TEX); ca. 62 mi WSW of Cuatro Cienegas, Sierra de Organos, Henrickson 12141 (TEX); ca. 35 km NW of Cuatro Cie- negas, Sierra de la Madera, Henrickson & Wendt 1 1848 (TEX); Puerto Colorado, Sierra de la Fragua, Johnston 8698 (GH, TEX); ca. 6 km S of Ejido La Noria, Sierra de San Marcos, Johnston et al. 10311 (TEX); Mina La Abun- dancia, Sierra de la Paila, Johnston et al. 10509A (TEX); Sierra San Marcos, Johnston et al. 10923 (TEX); Mina El Aguirreno, N side of Sierra de la Paila, Johnston et al. 11702 (TEX); 8 km W of Cuatro Cienegas, Sierra de la Madera, Johnston et al. 72079C(TEx); 9.5 km E of Puer- to del Gallo, Sierra de los Organos, Johnston et al. 12136D (TEX); Sierra de San Marcos, opposite Los Fresnos, Keil et al. 6082 (ASU); Canon de San Salvador, Sierra Mojada, Muller 3314 (F, GH, MICH, MO, TEX, uc); 6 km SE of Esmeralda, Sierra Mojada, Stewart 2218 (BM, F, GH, TEX); Canon de la Barrica, Wendt & Lott 1382 (TEX); Valle de Buenavista, Sierra Organos, Wendt & Lott 1416 (TEX); above El Pajarito, Sierra de la Fragua, Wendt & Lott 1427 (TEX); upper reaches of Canon Corazon del Toro at Mina La Abundancia, Wendt et al. 10 110 A (TEX). Flourensia retinophylla is distinguished from the other discoid taxa by its narrowly elliptic to lan- ceolate leaves and many-headed capitulescences. It occupies a wide altitudinal range, from just above the desert floor up to the highest portions of many canyons. Its associates include Acacia berlandieri, Agave lecheguilla, Arctostaphylos, Dasylirion, Hechtia, Pinus pinceana, Quercus intricata, Rhus virens, and Viguiera stenoloba. The present distribution of this species suggests 12 FIELDIANA: BOTANY 2cm FIG. 4. Flourensia retinophylla (from Dillon & Hartman 658, F). A, habit; B, capitulum; C, floret. that it may have been widespread at lower ele- vations within the Cuatro Cienegas basin during pluvial periods and became fragmented as more arid conditions developed at lower elevations. 3. Flourensia cernua DC., Prodr. 5: 593. 1836. TYPE: Mexico, Nuevo Leon, "ad Monterrey," Jan. 1828, /. L. Berlandier 1401 (lectotype, here designated, G-DC, IDC Microfiche 800. 952: I. 5!; isotypes BM!, F!, GH!, MO!). Figures 5, 13. Helianthus cernuus (DC.) Benth. & J. D. Hook, ex J. D. Hook & A. B. Jackson, Ind. Kew. 1:1112. 1893. Shrubs to 2 m tall; stems much-branched; branchlets, resinous, aromatic, brown to black, DILLON: SYSTEMATIC STUDY OF FLOURENSIA 13 FIG. 5. Distribution of Flourensia cernua. strigillose. Leaves elliptic to ovate, (10-) 17-25 (-40) mm long, 5-12 (-20) mm wide, upper and lower surfaces strigillose, basally cuneate, apically acute, the margins entire, strigillose, often undu- late; petioles 1-5 mm long, strigillose. Capitules- cences solitary, terminal and axillary, spiciform; peduncles to 10 mm long, bracteate. Capitula dis- coid, 5-10 mm high, 5-10 mm wide, nodding in fruit; involucres cylindrical; phyllaries ca. 3-seri- ate, imbricate, subherbaceous, ciliolate, lanceolate to ovate-lanceolate, 3-5 mm long, 1-2 mm wide; paleae lanceolate, 5-9 mm long, apically acute to attenuate; florets 10-25 (-40), the corollas cylin- drical, 3-4 mm long, the tube ca. 1 mm long, the lobes ca. 0.3 mm long. Achenes obconical to cu- neate, 4-6.5 mm long, villous; pappus of 2 awns, 2.5-3.5 mm long. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— Septem- ber-November (December-March). DISTRIBUTION AND HABITAT (Fio. 5)— Frequent on caliche and sandy soil throughout the Chihua- huan Desert region of north-central Mexico, in- cluding the states of Chihuahua, Coahuila, Du- rango, Guanajuato, Hidalgo, Nuevo Leon, San Luis Potosi, and Zacatecas, and the southwestern United States, including Arizona, New Mexico, and Texas (800-2,000 m). 14 FIELDIANA: BOTANY VERNACULAR NAMES— Blackbrush, tarbush, varnish bush; hojase, hojasen, ojasen. REPRESENTATIVE SPECIMENS EXAMINED— MEXICO. Chihuahua: 45 mi SE of Delicias, Dillon & Hartman 645 (TEX); hills and plains near Chihuahua, Pringle 292 (A, BM, F, GOET, MICH, us). C'oahuila: 1.5 km W of Tres Lomas, Chiang et al. 10057* (TEX); 3 mi S of Agua Nueva, 20 mi S of Saltillo, Dillon & Hartman 654* (F, TEX); Sierra de Paila, on road to Mina La Abundancia, Dillon & Hartman 657* (F, HUT, MEXU, MO, NY, TEX, us); near Saltillo, Palmer 286 (A, F, GH, MO, MSC, us); at Parras and vicinity, Palmer 434 (BM, F, GH, MO, uc, us). Durango: 2 mi S of Pedricena, 54 mi S of Gomez Palacio, Dillon & Hartman 649 (F, TEX); 27 km SW of Ceballos, Wendt et al. 9979* (TEX). Guanajuato: ca. 2 km E of Fabrica de Melchor, SW of Municipio de San Felipe, Rzedowski 9541 (ENCB). Hidalgo: ca. 10 mi SE of Ixmi- quilpan, 20 mi NW of Actopan, Dillon & Reynolds 675 (TEX). Nuevo Leon: ca. 3 mi S of San Roberto Junction, ca. 75 mi N of Matehuala, Cronquist 9833 (GH, MO, MSC, TEX, us). San Luis Potosi: region of San Luis Potosi, Parry & Palmer 469 (BM, F, MO, us). Zacatecas: 38.5 mi N of Zacatecas, 1 2.5 km N of Banon, Dillon & Hartman 651* (F, MEXU, TEX). UNITED STATES. Arizona: Cochise Co.: Portal to Paradise, Chiricahua National Forest, Eggleston 10667 (us). New Mexico: Dona Ana Co.: 27.7 mi E of Las Cruces, Dunn 5335 (us); Eddy Co.: road to Carlsbad Cavern, Standley 40376 (us); Grant Co.: Hachita, Goldman 1306 (us); Luna Co.: 12 mi E of Deming, Dillon & Baker 723 (F, TEX); Otero Co.: Tu- larosa, Gaul 20 (us); Sierra Co.: Las Palomas, Goldman 1792 (us). Texas: Brewster Co.: 9 mi S of Marathon, Dillon & Baker 714* (F, TEX); Crane Co.: ca. 16 mi W of Crane, Warnock 14638 (LL); Crocket Co.: 31.3 mi W of Ozona, Dillon 419 (TEX); Culberson Co.: 9 mi W of Kent, Dillon & Baker 719* (F, TEX); El Paso Co.: N end of Franklin Mts., Correll 26528 (LL, uc); Howard Co.: Big Springs, Bray 401 (TEX, us); Hudspeth Co.: 20 mi W of Van Horn, Dillon & Baker 721* (F, TEX); Jeff Davis Co.: 34 mi N of McDonald Observatory, Dillon & Baker 717 (F, TEX); Mitchell Co.: 26 mi S of Colorado City, Cory 49345 (GH); Pecos Co.: 1 mi S of Ft. Stockton, Dillon & Baker 711* (F, TEX); Presidio Co.: 23 mi S of Marfa, Muller 5081 (GH, LL); Reagan Co.: between Up- ton Co. line and Texon, Correll & Correll 27118 (TEX). Val Verde Co.: Comstock, Palmer 11062 (A, us). Flourensia cernua is easily distinguished by its small, entire, ovate to oval leaves and small, nearly sessile discoid capitula. The pungent odor of its foliage is also quite characteristic. There is con- siderable variation in leaf size within its range; the smallest leaves are found in southeastern popu- lations, the largest in the northwest (Arizona and New Mexico). This is the only widespread species within the genus in North America. It is a co-dominant with Larrea tridentata over much of its distribution in north-central Mexico and the southwestern United States. This type of vegetation was referred to by Muller ( 1 940) as the Larrea- Flourensia climax as- sociation. Gardner (1951) suggested that L. tri- dentata outlives F. cernua in such mixed com- munities, and Larrea eventually becomes the postclimax dominant. Flourensia cernua has long been used medici- nally by native peoples and is still sold in markets of central Mexico. It was listed by Martinez (1 969) as an indigestion remedy. A tincture is prepared from several grams of leaves placed in 90% ethanol and consumed along or mixed with another bev- erage. Maxwell (1968) stated that it was used by curanderos of northern Mexico as a treatment of yellow jaundice. Flourensia cernua is poisonous to sheep and goats in western Texas and, probably, throughout its range. Controlled feeding experiments (Math- ews, 1944) using ripe achenes reportedly produced acute inflammation of the abomasum and duo- denum of sheep, goats, and rabbits, with death within 1 8 to 72 hours. Green leaves were not found to be toxic. Most poisoning is likely to occur in late fall and winter (December-March) when the fruiting heads are formed and more desirable for- age plants become depleted. Although the toxic agent has not been identified, F. cernua is known to possess several potentially toxic flavonoids and sesquiterpenes (Dillon et al., 1976; Dillon & Ma- bry, 1977; Kingston etal., 1971, 1975). Cattle loss- es from F. cernua have not been reported; either cattle do not feed heavily on this species or are tolerant to it. Flourensia cernua forms putative hybrids with F. resinosa (see discussion under the latter species). 4. Flourensia dentata S. F. Blake, J. Wash. Acad. Sci. 25: 315. 1935. TYPE: Mexico, Durango, Terreros near Pedriceno, "campos guayuleros, ad viam," 11 Nov. 1925, S. Juzepczuk 609 (holotype, us!; isotype, LE; isotype fragment, TEX!). Figures 6, 9. Rounded shrubs to 1 m tall; stems much- branched, the bark black to brown; branchlets red- dish brown, resinous, minutely strigillose. Leaves oblanceolate to elliptic, 10-25 (-37) mm long, 5- 1 5 mm wide, upper and lower surfaces minutely strigillose, basally cuneate, apically acute, the mar- gins dentate or dentate-serrate, 1-5 pairs of un- equal teeth, 0.5-5 mm long, acute, axillary leaves occasionally entire; petioles 1-4 mm long, strigil- lose. Capitulescences solitary, or weakly cymose, DILLON: SYSTEMATIC STUDY OF FLOURENSIA 15 1cm 5mm FIG. 6. Flourensia dentata (from Dillon & Hartman 652, F). A, habit; B, capitulum; C, floret. 1-3-headed; peduncles 1-4 cm long, bracteate. Capitula discoid, 9-1 1 mm high, ca. 8 mm wide; involucres cylindrical, substended at base by 1-3 spatulate or oblanceolate leaves; phyllaries 2-3- seriate, subequal, subherbaceous, the outer linear- oblong to linear-lanceolate, 6-10 mm long, 1.5- 2.5 mm wide, apically acute, ciliolate, the inner oblong to oblanceolate, 7-9 mm long, 2-4 mm wide, apically obtuse to rounded, erose-lacerate; paleae oblanceolate, ca. 8.5 mm long, apically rounded, erose-lacerate, the margins scarious; flo- rets 1 5-25, the corollas cylindrical, ca. 5 mm long, the tube ca. 1 mm long, the lobes 0.5-0.8 mm long. Achenes cuneate, ca. 6 mm long, sericeous; pappus of 2 awns, 3-4 mm long, deciduous or rarely absent. FLOWERING (AND FRUITING) PERIOD— Septem- ber-November (November-January). DISTRIBUTION AND HABITAT (Fio. 9)— Scattered populations occur on limestone soils from central 16 FIELDIANA: BOTANY FIG. 7. Flourensia ilicifolia (from Purpus 1105, F). A, habit; B, capitulum; C, floret. 5mm 5mm 2cm Zacatecas, north to the Rio Nazas basin in eastern Durango (1,500-2,100 m). SPECIMENS EXAMINED— MEXICO. Durango: Menores and vicinity in Rio Nazas Basin, Gentry 8611 (GH, MICH, uc); Sombreretillo, Juzepczuk 550 (us); near La Puri- sima, Shreve 9180 (ARIZ, GH, MICH, uc). Zacatecas: 38.5 mi N of Zacatecas, 12.5 mi N of Ban6n, Dillon & Hart- man 652 (F, GH, HUT, MEXU, MO, NY, TEX, us); 17 mi NE of Zacatecas, Hartman et al. 3848 (TEX); 11 mi N of Sierra Hermosa, Johnston 7400 (GH, us); 14 mi S of Sta. Maria de Ban6n, Johnston 7441 (GH, us); 11 mi N of Sierra Hermosa, Shreve 8587 (ARIZ, us); 58.6 km N of Fresnillo, Wendl et al. 2185 (F). DILLON: SYSTEMATIC STUDY OF FLOURENSIA 17 5mm 2cm 5mm FIG. 8. Flourensia solitaria (from Henrickson & Dillon 15602, F). A, habit; B, capitulum; C, floret. Flourensia dentata and F. ilicifolia are the only Flourensias with discoid heads and toothed leaves. Flourensia dentata is readily distinguished by its smaller and narrower dentate leaves and corolla lobes less than 1 mm long. In central Zacatecas, Flourensia dentata and F. cernua occur sympatrically in the Opuntia scrub and intermittent grasslands. Individuals often oc- cur within a few meters of each other. Efforts to detect hybrids have been unsuccessful. 18 FIELDIANA: BOTANY •fa Flourensia laurifolia Flourensia retinophylla Flourensia dentata Flourensia ilicifolia A Flourensia solitaria FIG. 9. Distribution of Flourensia dentata, F. ilicifolia, F. laurifolia, F. retinophylla, and F. solitaria. 5. Flourensia ilicifolia Brandegee, Zoe 5: 238. 1906. TYPE: Mexico, Coahuila, Sierra de Parras, Mar. 1905, /. A. Purpus 1150 (holotype, uc!; iso- types, BM!, F!, GH!, MO!, NY!). Figures 7, 9. Shrubs to 1.5 m tall; stems much-branched; branchlets grayish brown, resin-encrusted, puber- ulent. Leaves rhombic-ovate, 1-2.5 (-5.5) cm long, 0.6-1.5 (-2.5) cm wide, puberulent to glabrescent, basally cuneate, apically acute, the margins den- tate with 3-6 pairs of stiff, mucronate teeth (rarely entire); petioles 2-4 (-6) mm long, puberulent. Capitulescences solitary or in 2-3-headed terminal clusters; peduncles to 1 cm long, puberulent, 1-3- bracteate, the bracts linear-spathulate, 5-7 mm long. Capitula discoid, 10-15 mm high, 10-13 mm wide; involucres campanulate to cylindrical; phyl- laries 2-seriate, subequal, coriaceous, oblong to oblong-ovate, 5-7 mm long, 1.0-2^5_ mm wide, apically obtuse, ciliolate; paleae oblanceolate, 7- 9 mm long, apically cucullate, obtuse to rounded, lacerate, scarious; florets 20-30, the corollas cy- lindric-campanulate, ca. 6.5 mm long, the tube ca. 1 mm long, the lobes ca. 2.5 mm long. Achenes cuneate, 7-9 mm long, sericeous; pappus of 2 awns, 2.5-4.5 mm long, persistent, broadly lanceolate, basally ampliate, united by a low crown of fused hairs, 2-3 mm long. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 19 FLOWERING (AND FRUITING) PERIOD— Septem- ber-October (October-November). DISTRIBUTION AND HABITAT (Fio. 9.)— Endemic to the Sierra de Parras, in south-central Coahuila, Mexico. The population occurs predominantly in dry canyons on calcareous gravel, but occasional individuals occur on lower bajadas in close prox- imity to Flourensia cernua (1,600-1,800 m). SPECIMENS EXAMINED— MEXICO. Coahuila: 1 km W of Parras, Dillon et al. 629 (F, MEXU, TEX); Sierra de Parras, Johnston et al. 10996 (TEX); Sierra de Parras, Shreve & Tinkham 9878 (GH). Flourensia ilicifolia is distinguished by its rhom- bic-ovate, dentate leaves with mucronate-tipped teeth and its loose involucre with large, obtuse phyllaries. It also possesses characteristically long corolla lobes, ca. 2.5 mm long versus ca. 1 mm long for most congeners. 6. Flourensia solitaria S. F. Blake, J. Wash. Acad. Sci. 40: 49. 1950. TYPE: Mexico, Coahuila, rocky flats and slopes, top of grade at Cuesta de Zozaya, road from Ocampo W over mountains to Puertecito via Cuesta de Zozaya, 20 Sept. 1941, /. M. Johnston 9289 (holotype, GH!; iso- types, TEX!, us!). Figures 8, 9. Shrubs to 60 cm tall; stems much-branched, the back gray to brown, fissured, aromatic, strigillose. Leaves oblanceolate to obovate, 1.2-3.3 cm long, 0.3-1 cm wide, upper and lower surfaces minutely strigillose, basally cuneate, sessile to subsessile, apically acute, the margins entire, undulate, strigil- lose. Capitulescences solitary, terminal; peduncles 1 3-20 cm long, strigillose, reddish brown, multi- bracteate. Capitula discoid, ca. 12 mm high, 8-13 mm wide; involucres campunulate; phyllaries 5- seriate, imbricate, the outer lanceolate, 3.5-5 mm long, 1-1.5 mm wide, the inner oblong-obovate to rhombic, 4.5-6 mm long, 1.5-2.5 mm wide, all basally indurate, stramineous, apically herba- ceous, acute, strigillose; paleae rhombic-obovate to narrowly cuneate-spatulate, 10- 12 mm long, 1- 3 mm wide, apically acute, scarious, strigillose. Achenes cylindrical to oblong-lanceolate, 4.8-5.5 mm long, ca. 2.2 mm wide, 5-6-ribbed, obscurely puberulent; epappose. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— Septem- ber-November (December-January). DISTRIBUTION AND HABITAT (Fio. 9)— This rare species is known only from the type locality and one additional site, both in central Coahuila, Mex- ico. Although limited in distribution, it is quite dominant locally in small areas of rocky, coarse soils on flat hillside terraces (400-1,000 m). SPECIMENS EXAMINED— MEXICO. Coahuila: 18 mi WSW of Villa Ocampo at Cuesta Zozaya, limestone E-W pass, on road to Laguna del Rey, Henrickson & Dillon 15602 (F, MEXU, TEX); Cuesta de Zozaya, 23 mi W of Ocampo, 12.5 mi E of Puertecitos, Wendt & Lott 1438 (TEX), 1873* (TEX); Puerto del Guarache, in Sierra de Zacatosa, about 2.5 mi SW of Arocha, Wendt & Lott 1425 (TEX). Flourensia solitaria is unique within the genus in possessing solitary, discoid capitula borne on long peduncles and achenes lacking the usual se- riceous or villous pubescence. This species occurs in very xeric and windblown habitats just above the Flourensia cernua-Larrea tridentata formation. Its associates include Agave falcata, A. lecheguilla, Dasylirion, Hechtia, Koe- berlinia, and Opuntia. 7. Flourensia microphylla (A. Gray) S. F. Blake, Proc. Amer. Acad. Arts 49: 374. 1913. Figures 10, 18. Encelia microphylla A. Gray, Proc. Amer. Acad. Arts 15: 37. 1879. TYPE: Mexico, Coahuila, gravelly hills near Saltillo, Aug. 1878, C. C. Parry 462 (ho- lotype, GH!). Shrubs to 1 m; stems much-branched, the bark grayish brown, densely hispid-pilose; branchlets purplish brown, striate. Leaves ovate to elliptic- ovate, 1.5-2.5 cm long, 0.5-1 cm wide, upper and lower surfaces strigillose, acute at each end, the margins entire, undulate, strigillose; petioles 1.5- 4 mm long, hispid-pilose. Capitulescences soli- tary, terminal; peduncles 3-12 cm long, multi- bracteate. Capitula radiate, 10-15 mm high, 10- 1 5 mm wide; involucres cylindrical; phyllaries 2- 3-seriate, subequal, herbaceous, hispid-pilose, the outer narrowly lanceolate, 8-10 mm long, ca. 2 mm wide, apically acute, the inner lance-ovate to lance-obovate, 10-15 mm long, 2-2.5 mm wide, apically attenuate; paleae lanceolate, ca. 12-14 mm long, apically acute, ciliolate; ray florets ca. 10, neuter (rarely with a vestigial achene), the ligules oval to ovate, ca. 10 mm long, 4-6 mm wide; disc florets ca. 36, the corollas cylindric, ca. 6 mm long, the tube 1-2 mm long, the lobes 0.5-0.8 mm long, puberulent. Achenes oblong-obovate, 4-6 mm 20 FIELDIANA: BOTANY 2cm 5mm 5mm 1cm FIG. 10. Flourensia microphylla (from Palmer 795, F). A, habit; B, capitulum; C, disc floret; D, ray floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 21 long, densely pilose-sericeous; pappus of 2 awns, ca. 3 mm long, caducous. FLOWERING (AND FRUITING) PERIOD— Septem- ber (October). DISTRIBUTION AND HABITAT (Fio. 18)— Very rare and known from only a few collections from dry, limestone slopes of the mountains in south- eastern Coahuila, Mexico. SPECIMENS EXAMINED— MEXICO. Coahuila: Sierra de San Marcos, opposite Los Fresnos, Keil et al. P110B (ASU); vicinity of Saltillo, Palmer 795 (BM, F, GH, MO, MSC, NY, uc, us); Cameras Pass, Pringle 2392 (BM, F, GH, MO, MSC, NY, uc, us); no exact locality, Palmer 589 (GH). Flourensia microphylla is unique among the North American species in possessing small ovate to elliptic-ovate leaves and solitary, radiate heads borne on long peduncles. This rare species was re-discovered in 1 969 by collectors (Keil et al. P110B, ASU) in the Sierra de San Marcos. This marked the first collection of this species since 1898. Though the type collection of this species was cited as C. C. Parry andE. Palmer 462 by A. Gray and subsequent authors, it is likely that 462 was solely a Parry collection. The type sheet at GH has only Parry's name on his personal label with the printed locality, "En route from San Luis Potosi to San Antonio, Texas." Moreover, Parry collect- ed alone between April and the end of July (1878), a time when Palmer was in Mexico City. Parry left San Luis Potosi for his home in Iowa around the first of August, but fell ill and stayed in Saltillo for 10 days to recuperate (McVaugh, 1956). After Parry left, Palmer collected exclusively in the state of San Luis Potosi for the next three months. 8. Flourensia colludes (Greenman) S. F. Blake, Proc. Amer. Acad. Arts 49: 373. 1913. Figures 11, 14. Encelia collodes Greenman, Proc. Amer. Acad. Arts 39: 1 10. 1903. TYPE: Mexico, Chiapas, along road from Ocuilapa to Tuxtla, 2,100-3,000 ft, 29 Aug. 1895, E. W. Nelson 3071 (holotype, GH!; isotype, us!). Arborescent shrubs to 4 m tall; stems grayish brown; branchlets striate, pilose to glabrescent. Leaves lance-ovate to ovate, 6-14 cm long, 2.2- 6.4 cm wide, mostly falcate, upper surface sparsely strigillose, lower surface glabrous, basally oblique, rounded, apically acute to attenuate, the margins entire, strigillose; petioles 7-20 mm long, strigil- lose. Capitulescences weakly cymose, 4-5 -head- ed; peduncles 2-8 cm long, bracteate. Capitula radiate, ca. 1.5 cm high, ca. 2 cm wide; involucres hemispheric; phyllaries 3-4-seriate, imbricate, in- durate, striate, the outer lanceolate, 4-6 mm long, 1-1.5 mm wide, apically acute, subherbaceous, ciliolate, the inner oblanceolate, 7-10 mm long, 1.5-2 mm wide, apically acute to obtuse; paleae oblong, 12-15 mm long, apically subcucullate, rounded, erose, ciliolate; ray florets ( 1 2-) 1 3 (- 1 6), neuter (rarely styliferous), the ligules narrowly el- liptic, 1 5-22 mm long, 5-8 mm wide, the tube 5- 6 mm long, glabrous; disc florets 30-100, the co- rollas cylindric, ca. 6 mm long, the tube 1-1.5 mm long, the lobes 0.6-1 mm long. Achenes obconical to cuneate, 6-10 mm long, sericeous on margins, the faces glabrate, reddish brown; pappus of 2 awns, 4-7 mm long, persistent, basally ampliate, lacer- ate. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— August- October (November-December). DISTRIBUTION AND HABITAT (FiG. 14)— Infre- quent on thin, rocky soils in the Tropical Decid- uous Forest in the extreme southern portion of the Mesa del Sur, Oaxaca, and the Central Depression of Chiapas, Mexico (400-1,000 m). SPECIMENS EXAMINED— MEXICO. Chiapas: 5 km E of Berriozabal on Mex Hwy 190, Breedlove 20388 (DS). Oaxaca: 100 mi SE of Oaxaca, 54 mi NE of Tehuantepec, Cronquist & Sousa 10453 (ENCB, GH, MICH, MCS, us); 45 mi SE of Oaxaca, Dillon & Reynolds 696 (F, HUT, MEXU, TEX); San Pedro Oscurana, MacDougall s.n. (us); San Pedro Istmo, MacDougall s.n. (us). Flourensia collodes is distinguished by its large, falcate, lance-ovate leaves and capitula with ( 1 2-) 1 3 (-1 6) ray florets. Its associates include Bursera, Ceiba, and Heliocarpus. Although, in Greenman's description, he cited the type collection as Nelson 307, it is clearly marked as 3071 on the holotype and isotype spec- imens. 9. Flourensia glutinosa (Robinson & Greenman) S. F. Blake, Proc. Amer. Acad. Arts 49: 374. 1913. Figures 12, 14. Encelia glutinosa Robinson & Greenman, Amer. J. Sci. III. 50: 1955. 1895. TYPE: Mexico, Oaxaca, Las Hoyas Canyon, 4,500 ft, 2 Nov. 1894, C. G. 22 FIELDIANA: BOTANY 1cm 2cm FIG. 1 1. Flour ensia col lodes (from Dillon & Reynolds 696, F). A, habit; B, capitulum. Pringle 6024 (holotype, GH!; isotypes, A!, BM!, MO!, MSC!, NY!, uc!, us!). Arborescent shrubs to 5 m tall, the bark gray, furrowed; branchlets pilose-lanate. Leaves ovate to ovate-lanceolate, 4.5-13 cm long, 1.5-3.8 cm wide, falcate, upper surface minutely strigillose, lower surface glabrous, basally cuneate, apically acuminate, the margins entire, strigillose; petioles 2-4 mm long, lanate-pilose to glabrescent. Capitu- lescences cymose-paniculate, 5-20-headed; pe- duncles 2-5 cm long, striate, puberulent, brac- teate. Capitula radiate, 1-1.5 cm high, ca. 1 cm wide; involucres hemispheric; phyllaries 3-4-se- riate, imbricate, indurate, striate, the outer lan- ceolate, 2-3.5 mm long, 0.6-1 mm wide, apically acute, ciliolate, the inner oblong- lanceolate, 3-5.5 mm long, 1-1.5 mm wide, apically attenuate to obtuse, ciliolate; paleae oblanceolate, 8-1 1 mm long, apically truncate and crested with two scar- ious wings, ciliolate; ray florets 7-10, the ligules oblong-oval, 11-23 mm long, 5-7 mm wide, the tube pilose; disc florets ca. 40, the corollas cylin- drical, ca. 7 mm long, the tube ca. 1.5 mm long, the lobes ca. 1.5 mm long. Achenes obconical to narrowly cuneate, 6.5-1 1 mm long, sericeous-pi - DILLON: SYSTEMATIC STUDY OF FLOURENSIA 23 2cm FIG. 12. Flourensia glutinosa (from Dillon & Reynolds 678, F). A, habit; B, capitulum; C, disc floret. lose; pappus of 2 (rarely 4) awns, 2-5 mm long, occasionally deciduous. FLOWERING (AND FRUITING) PERIOD— October- November (November-December). DISTRIBUTION AND HABITAT (Fie. 14)— Infre- quent on limestone and shale slopes in the valleys of the Mesa del Sur of southern Puebla and western Oaxaca (1,400-1,600 m). SPECIMENS EXAMINED— MEXICO. Oaxaca: 50 km NNW of Teliztlahuaca, along road to Tehuacan, Cron- quist & Fay 10923 (ENCB, F, GH, MICH, MSC, NY, TEX, us); 6 mi above Domiquillo, Nelson 1832 (GH, us). Puebla: 14 mi NW of Huajuapan de Leon, Dillon & Reynolds 678 (F, GH, HUT, MEXU, MO, NY, TEX, US). Flourensia glutinosa is distinguished by its ar- borescent habit and 5-20-headed, cymose-panicu- 24 FIELDIANA: BOTANY FIG. 13. A-C, Flourensia cernua (from Cronquist 11262, MO). A, habit; B, capitulum; C, floret. D, F. cernua x F. resinosa (from Cronquist 11263, MO). E-G, F. resinosa (from Cronquist 9626, MO). E, habit; F, capitulum; G, disc floret. late capitulescences. Its associates include Brahea, Opuntia, and Tithonia. 10. Flourensia resinosa (Brandegee) S. F. Blake, Proc. Amer. Acad. Arts 49: 375. 1913. Figures 13, 14. Encelia resinosa Brandegee, Zoe 5: 240. 1906. TYPE: Mexico, Hidalgo, Ixmiquilpan. mountains, Aug. 1905, C. A. Purpus 1458 (holotype, uc!; isotypes F!, GH!, MO!, NY!). Shrubs to 2 m tall, the bark grayish brown to black; branchlets reddish brown, striate. Leaves lanceolate to narrowly oblong-elliptic, 3.5-7 cm long, 0.8-1.8 cm wide, upper and lower surfaces sparsely strigillose, basally acute to cuneate, api- cally acute, the margins entire, strigillose; petioles 2-4 mm long. Capitulescences weakly cymose, 2-4 (-S)-headed; peduncles 2-7 mm long, bracteate. Capitula radiate, 11-17 mm high, 10-17 mm wide; involucres hemispheric; phyllaries 3-seriate, sub- equal, herbaceous, narrowly lanceolate, 5-9 mm long, 1-2 mm wide, apically acute to acuminate; paleae oblanceolate, 8-12 mm long, apically acute to acuminate; ray florets ca. 10, the ligules oblong, 13-22 mm long, 5-9 mm wide, the tube puber- ulent; disc florets 30-50, the corollas cylindric, 6- 7 mm long, the tube ca. 1 mm long, the lobes ca. 1 mm long. Achenes obconical to cuneate, ca. 8 mm long, the margins sericeous, the faces sparsely sericeous, glabrescent; pappus to 2 awns, 3-5 mm long, persistent. Chromosome number: n = 18. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 25 50 100 200 mi. ««— 4— 1— * 1- M-l-l_( 1 , 50 150 225 km. ® ® O -15 O Flourensia collodes (§) Flourensia glutinosa Flourensia resinosa FIG. 14. Distribution of Flourensia collodes, F. glutinosa, and F. resinosa. FLOWERING (AND FRUITING) PERIOD— June-No- vember (December-January). DISTRIBUTION AND HABITAT (FiG. 14)— Domi- nant locally on low, arid, limestone hillsides in the vicinity of Ixmiquilpan, Hidalgo, Mexico (1,000- 1,900 m). This region is considered a southern extension of the Chihuahuan Desert (Rzedowski, 1973). REPRESENTATIVE SPECIMENS EXAMINED— MEXICO. Hidalgo: 1 2 km SE of Ixmiquilpan, Chiang et al. 855 (BM, F); 7 mi SE of Ixmiquilpan, Cronquist 9626 (GH, MICH, MO, TEX, us); 10 mi SE of Ixmiquilpan, Dillon & Reynolds 676 (F, MEXU, MO, NY, TEX); 6 mi S of Ixmi- quilpan, Graham & Johnston 4758* (TEX); El Capulin, between Actopan and Ixmiquilpan, Moore 1265 (BM, GH, MICH, us); ca. 2 mi W of Villagran, Quintero 2006 (TEX); 38 mi NW of Pachuca, Waterfall & Wallis 14098 (us). Flourensia resinosa is distinguished by its ex- tremely resinous, lanceolate to elliptic leaves and long- pedunculate capitula with 10 ray florets. Its associates include Agave, Dasylirion, Hechtia, Opuntia, Yucca, and Zaluzania. It is sympatric with Flourensia cernua at lower elevations within its distribution. Cronquist col- lected what he believed to be a hybrid from an area 15 km southeast of Ixmiquilpan (11263; F, GH, MO, NY, TEX, us). This specimen has charac- teristics intermediate between its supposed par- ents. Table 2 and Figure 13 compare these taxa. Further sampling will be necessary to assess the extent and direction of hybridization at this lo- cality. Schultz Bipontinus (ca. 1 840) annotated Ehren- berg 1564 (B), from the vicinity of Ixmiquilpan, as Flourensia glutinosa sp. nov.\ however, he pro- vided no description. Around 1914, Blake anno- tated the specimen as F. schultzii, since the epithet glutinosa was preoccupied, but also provided no description. In his revision, Blake (1921) recog- nized the specimen as F. resinosa, and from an examination of a photograph of that collection, I agree with Blake's placement. Label data from Moore 1265 indicate possible use of this species by local peoples as "edible ex- udate chewed like chicle." 26 FIELDIANA: BOTANY Although Brandegee cited Purpus 1456 as the type in the original description, the correct number of the collection is 1458. 1 1 . Flourensia monticola Dillon, Southw. Natu- ralist 21: 147. 1976. TYPE: Mexico, Coahuila, dry, limestone and shale slopes, 13.5 km E of Los Lirios, 24 km W of La Jacinta (N.L.) very near Nuevo Leon state line, 2,150 m, 7 Nov. 1972, F. Chiang, T. Wendt, & M. C. Johnston 10130 (holotype, TEX!; isotype, MEXU!). Figures 15, 18. Shrubs to 2 m tall; stems much-branched from base, ascending, the bark black. Leaves lanceo- late to obovate, 6-1 1.5 cm long, 2-4.5 cm wide, crowded at tips of branchlets, upper and lower surfaces sparsely strigillose, basally acute to cu- neate, apically acute, obtuse, or occasionally re- tuse, the margins entire, strigillose; petioles 1.8- 2.2 cm long. Capitulescences solitary (rarely 2-headed), terminal on branchlets; peduncles 4- 11 cm long, bracteate. Capitula radiate, 1.2-1.5 cm high, 1.5-2 cm wide; involucres hemispheric; phyllaries 3-seriate, subequal, herbaceous, the out- er lanceolate, 9-1 3 mm long, 2-2.5 mm wide, api- cally acute to attenuate, the inner ovate-lanceolate to oblong, 1 1-16 mm long, 2.5-3 mm wide, api- cally acute to acuminate; paleae oblanceolate, ca. 1 cm long, apically acute to attenuate: ray florets (10-) 1 3 (-1 5), the ligules oblong, 20-30 mm long, 5-7 mm wide; disc florets ca. 50, the corollas cy- lindric-campanulate, ca. 8 mm long, the tube ca. 1.5 mm long, the lobes ca. 1.5 mm long. Achenes obconical to cuneate, 8-9 mm long, the margins sericeous, the faces sparsely sericeous, glabrescent; pappus of 2 awns, ca. 5 mm long, persistent. Chro- mosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— July-No- vember (November-December). DISTRIBUTION AND HABITAT (Fio. 18)— Known from three localities in canyons of the northern Sierra Madre Oriental (ca. 2,150 m). This appar- ently local species is found on dry, southwest-fac- ing limestone and shale slopes. SPECIMENS EXAMINED— MEXICO. Coahuila: Canon de Los Lirios, 10 mi E of Los Lirios, on road to La Jacinta, N.L., and Cola de Caballo, Dillon & Hartman 656* (F, HUT, MEXU, MO, NY, TEX). Nuevo Leon: Can6n del Diente, S of Monterrey, C. H. & M. T. Mueller 252 (F, GH, MEXU, TEX); near Monterrey, Smith A/275 (TEX); Cerro de La Silla, White & Chatters 9 (MEXU, MICH). TABLE 2. Distinguishing characteristics of Flourensia cernua, F. resinosa. and a putative hybrid (values are given for the entire range of the taxa). Character F. cernua Putative hybrid F. resinosa Leaf length (cm) ca. 2.5-3.5 3.5-7 1.7-2.5 Peduncles (cm) ca. 1 1-5 2-7 Ray florets Absent 1-7 or ca. 10 absent Ligules length (cm) Absent <1 1.3-2.2 % Pollen stain- >90 ca. 36 >90 ability (> 500 grains each) Flourensia monticola is distinguished from F. resinosa and F. pulcherrima, its nearest relatives, by possessing wider leaves and capitula that are intermediate in size. In the vicinity of the type locality, it is associated with Agave, Finns, and Quercus. 12. Flourensia pulcherrima Dillon, Southw. Nat- uralist 21: 145. 1976. TYPE: Mexico, Durango, steep limestone slopes, N end of Sierra de Ro- sario, ca. 20 km SW of Mapimi and 3 km E of Santa Librada, 2,000 m, 25 June 1973, M. C. Johnston, F. Chiang, & T. Wendt 11469* (ho- lotype, TEX!; isotype, MEXU!). Figures 16, 18. Shrubs to 1.5 m tall; stems much-branched ba- sally, the bark black. Leaves lanceolate to narrowly elliptic, (5-) 8-12 (-15) cm long, 2-3 cm wide, upper and lower surfaces puberulent, attenuate at both ends, the margins entire. Capitulescences sol- itary, terminal on branchlets, or weakly cymose, 3-5-headed; peduncles 1-6 cm long, bracteate. Ca- pitula radiate, 1.5-2 cm high, 1.3-2 cm wide; in- volucre broadly hemispheric; phyllaries 2-seriate, the outer linear to lanceolate, 1 8-20 mm long, 2- 3 mm wide, the inner ovate-lanceolate, 10-12 mm long, 2-3 mm wide, all basally indurate, all api- cally attenuate, herbaceous, puberulent, reflexed in fruit; paleae oblanceolate, 10-15 mm long, api- cally acute to attenuate, ciliolate; ray florets ca. 1 3, the ligules oblong, 22-26 mm long, 5-6 mm wide, the tube ca. 6 mm long, sericeous; disc florets 50- 60 (-1 50), the corollas cylindric, 6-7 mm long, the tube ca. 1 mm long, the lobes ca. 1 mm long. Achenes obconical, 7-9 mm long, the margins se- riceous, the faces short-sericeous, glabrescent; DILLON: SYSTEMATIC STUDY OF FLOURENSIA 27 FIG. 15. Flourensia monticola (from Chiang, Wendt, & Johnston 10130, TEX). 28 FIELDIANA: BOTANY FIG. 16. Flourensia pulcherrima (from Johnston, Chiang, & Wendt 11469, TEX). DILLON: SYSTEMATIC STUDY OF FLOURENSIA 29 pappus of 2 awns, 3-5 (-6) mm long, persistent. Chromosome number: n — 1 8. FLOWERING (AND FRUITING) PERIOD— June-Oc- tober (October-November). DISTRIBUTION AND HABITAT (Fio. 18)— Found on steep, limestone slopes in the mountains as- sociated with the Bolson de Mapimi in eastern Chihuahua, northeastern Durango, and south- western Coahuila, Mexico (1,500-2,100 m). SPECIMENS EXAMINED— MEXICO. Chihuahua: Sierra de las Pampas, Chiang et al. 8836 (TEX); 20 km ENE of Cd. Jimenez, NW of summit of Sierra de Chupaderos, Henrickson 13754 (TEX). Coahuila: ca. 26 mi SE of Tor- re6n, Sierra de Jimulco, Henrickson 13130 (TEX); Sierra de Jimulco, Johnston et al. 11506 (TEX). Durango: N end of Sierra del Rosario, ca. 20 km SW of Mapimi, Dillon & Hartman 647 (F, MO, TEX); Sierra del Rosario, Wendt et al. 10014 (TEX). Flourensia pulcherrima is distinguished by its narrowly lanceolate to elliptic leaves and long phyllaries, often overtopping the disc. Its associ- ates include Agave, Dasylirion, Fouquieria, and Yucca. 1 3. Flourensia pringlei (A. Gray) S. F. Blake, Proc. Amer. Acad. Arts 49: 375. 1913. Figures 17, 18. Helianthella pringlei A. Gray, Proc. Amer. Acad. Arts 21: 389. 1886. TYPE: Mexico, Chihuahua, rocky hills near Chihuahua City, 7 Sept. 1885, C. G. Prin- gle 646 (holotype, GH!; isotypes, BM!, F!, MO!, NY!, us!). Encelia oblonga Robinson & Fern., Proc. Amer. Acad. Arts 30: 118. 1894. TYPE: Mexico, Chihuahua, plains near Casas Grandes, 10 Oct. 1891, C. V. Hartman 812 (holotype, GH!; isotype, us!). Suffruticose subshrubs to 1 m tall; stems erect; usually unbranched, yellowish green. Leaves ellip- tic to oblong-lanceolate (2-) 5-10 cm long, 1-4.3 cm wide, upper and lower surfaces strigose, basally cuneate, apically acute to rounded, the margins entire, strigose. Capitulescences solitary, terminal; peduncles 5-1 1 cm long, bracteate. Capitula ra- diate, 1-2 cm high, 1.5-2.5 cm wide; involucres broadly hemispheric, subtended by calyculate, fo- liaceous bracts; phyllaries ca. 2-seriate, linear from ovate base, 10-30 mm long, 1.5-2 mm wide, api- cally attenuate, ciliolate; paleae oblanceolate, ca. 1 1 mm long, apically acute to obtuse; ray florets 1 3-2 1 , the ligules oblong to oval, 10-16 mm long, 3-4 mm wide, the tube 5-7 mm long, sericeous; disc florets 40-50, the corollas cylindric, ca. 6.5 mm long, the tube ca. 1 mm long, the lobes ca. 1 mm long. Achenes cuneate, ca. 12 mm long, 4-8- ribbed, subterete, sericeous, pappus of 2 awns, ca. 4 mm long, persistent or disarticulating. FLOWERING (AND FRUITING) PERIOD— August- October (September-October). DISTRIBUTION AND HABITAT (Fio. 18)— Known from rocky foothills of the eastern Sierra Madre Occidental from southwestern New Mexico, United States, and central Chihuahua to central Durango, Mexico (1,500-2,100 m). SPECIMENS EXAMINED— MEXICO. Chihuahua: Ran- cho Tepehuanes, Namiquipa, Enriquez 207 (F, TEX); 4 mi S of Matamoros, Gentry & Arguelles 17927 (TEX, us); 4.6 mi NE of Buenaventura, Oliver et al. 542 (MO); hills near Chihuahua, Pringle 1056 (F, MO, MSC, NY, uc). Du- rango: El Oro to Guanacevi, Nelson 4730 (us); vicinity of Santiago Papasquiaro, Palmer 425 (BM, F, GH, MO, NY, uc, us). UNITED STATES. New Mexico: Hidalgo Co.: along SW side of Alamo Hueco Mts., R. & M. Spellen- berg 3861 (NY, TEX). Flourensia pringlei is distinguished by its suf- fruticose habit with 6-12 erect, leafy stems and large capitula with long linear phyllaries. In south- western New Mexico, it is found on severely ov- ergrazed slopes that are eroded down to cobble- stone. Its associates in this area include Fouquieria, Jatropha macrorhiza, Juniperus, Pectis filipes, P. prostrata, Portulaca suffrutescens, Quercus arizo- nica, Talinum paniculatum, and T. parviflorum (R. Spellenberg, pers. comm.). 14. Flourensia thurifera (Molina) DC., Prodr. 5: 592. 1836. Figures 19, 20. Helianthus thurifera Molina, Sagg. Stor. Nat. Chil. 1 60. 1782. TYPE: Chile, Valparaiso, vicinity of Valpa- raiso, Molina s.n. The holotype has not been located at Bolo where it may have originally been deposited. NEOTYPE: Chile, Valparaiso, sonnige Abhange, 7 Oct. 1895, Buchtien s.n. (neotype, us!, photograph, F!; isoneotype, GH!, photograph, F!). Diomedea thurifera (Molina) Bertero ex Colla, Mem. Acad. Sci. Torino 38: 37. 1835. Helianthus glutinosus Hook. & Am., Bot. Beechey Voy. p. 32. 1830. TYPE: Chile, Valparaiso, T. Bridges s.n. (holotype, GL, not seen). Flourensia besseriana Meyen & Walp., Nov. Act. Aca. Caes. Leop. Carol. 19: 270. TYPE: Chile, no exact locality, B. Besser s.n. (holotype, B, destroyed; lec- totype, here designated, fragment, GH!; photograph of B specimen, F!, GH!). Helianthus besseriana (Meyen & Walp.) Benth. & J. D. Hook, ex J. D. Hook. & A. B. Jackson, Ind. Kew. 1: 1112. 1893. 30 FIELDIANA: BOTANY 2 cm FIG. 17. Flourensia pringlei. A, habit (from Pringle 1056, F); B, capitulum (from Palmer 425, F). DILLON: SYSTEMATIC STUDY OF FLOURENSIA 31 —25 •20 Flourensia microphylla Flourensia monticola Flourensia pulcherrima Flourensia pringlei FIG. 18. Distribution of Flourensia microphylla, F. monticola, F. pringlei, and F. pulcherrima. Flourensia thurifera var. lanceolata Remy in Gay, Hist. Chil. 4: 288. 1849. TYPE: p, not seen. Shrubs to 2 m tall; stems erect, the bark brown; branchlets reddish brown, puberulent. Leaves ovate to oblong-elliptic, 5.5-11.5 cm long, 1 .5-4 cm wide, upper and lower surfaces strigillose, basally cu- neate, apically subacuminate to obtuse, the mar- gins shallowly repand-dentate with 4-10 pairs of triangular, mucronate teeth (rarely subentire), strigillose; petioles 3-9 mm long, villosulose. Ca- pitulescences cymose, 4-8 -headed; peduncles 3- 1 3 cm long, bracteate. Capitula radiate, 10-15 mm high, 14-25 mm wide; involucres hemispheric; phyllaries 2-3-seriate, subequal, herbaceous, densely to sparsely villous, lanceolate to oblong- spatulate, 6-17 mm long, 1-3 mm wide, apically acute to acuminate, mucronulate; paleae oblan- ceolate 9-10 mm long, apically obtuse to rounded, often puberulent; ray florets ca. 13, the ligules oval to oblong-oval, 14-30 mm long, 5-10 mm wide, the tube villosulose; disc florets ca. 50, the corollas slender- funnelform, ca. 6.5 mm long, the tube ca. 2 mm long, the lobes ca. 0.6 mm long, puberulent. Achenes oblong-cuneate to obconical, 7-8 mm long, densely sericeous; pappus of 2-3 (rarely 4) awns, 3-4 mm long, basally ampliate, persistent. Chromosome number: 2n = 36. 32 FIELDIANA: BOTANY I cm FIG. 19. Flourensia thurifera (from Behn s.n., F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 33 — 30 •32 — 36 FIG. 20. Distribution of Flourensia thurifera. FLOWERING (AND FRUITING) PERIOD— August- November (November-December). DISTRIBUTION AND HABITAT (Fie. 20). — Fre- quent in the evergreen sclerophyllous scrub of coastal Chile from Coquimbo, south to Santiago, and one collection from near Concepcion (400- 1,000m). VERNACULAR NAMES— Flor del incienso, incien- so, maravilla, maravilla del campo, maravilla del cerro. REPRESENTATIVE SPECIMENS EXAMINED— CHILE. Aconcagua: San Felipe, Claude-Joseph 1353 (us); Que- mados to Zapallar, Kausel 2578 (LIL); between Calera and San Felip, Killip & Pisano 39769 (us). Concepcion: Tome, Vera 25 (LIL). Coquimbo: 40 km S of La Serena, Cabrera 12582 (LP); Cuesta Los Hornos, ca. 10 km from Illapel, Kausel 4597 (LP); Tulahuen, Geisse s.n. (GH); Fray Jorge, Jiles 306 (si), 707 (LIL); Tongoycillo, Jiles 1519 (LP); Zorrilla, Jiles 1623 (LIL); Quebrada de La- marones, S of La Serena, Solbrig 3043 (GH); Vicuna, Wagenknecht 18471 (F, GH, uc, MO); Rivadavia, Wer- dermann 90 (A, BM, F, GH, LIL, NY, si, uc). Santiago: Cerro San Cristobal, Cabrera 11330 (LP); Santiago, Claude-Joseph 922 (us); Tiltil, Grandjot s.n. (MO); Cerro de Renca, Looser 2942 (TEX). Valparaiso: Valparaiso, Bertero 954 (BM, F, GH, MO); Llay-Llay, Cabrera 12516 (LP); Marga-Marga, Jaffuel 3659 (GH); Limache, Looser 627 (GH). Flourensia thurifera is distinguished by its large ovate to oblong-elliptic, shallowly repand-dentate 34 FIELDIANA: BOTANY leaves, foliaceous phyllaries, and large capitula and rays. There is considerable variation in leaf shape and size that is presumably environmentally in- duced; capitular morphology is quite constant. Carhuaz and Yungay, Ferreyra 14337 (USM). La Liber- tad: Santiago de Chuco, Los Quengos, Ldpez 435 (LIL, LP, USM), 970 (HUT). Lima: Huarochiri, KM 86 near Matucana, Ferreyra 7014 (us, USM); Matucana, Mac- bride 2929 (F), Macbride & Featherstone 247 (F, GH, us). 15. Flourensia macrophylla S. F. Blake, Bot. Jahrb. Syst. 54: 47. 1916. TYPE: Peru, Lima, Huaro- chiri, stony places, 2,370-2,650 m, along Lima- Oroya Railroad, between Matucana and Tambo de Viso, 26 Dec. 1901, A. Weberbauer 119 (ho- lotype, B, destroyed; lectotype, here designated, fragment, GH!; photograph of B specimen, F!, GH!). Figures 21, 26. Shrubs to 2 m; stems much-branched, the bark black; branchlets reddish brown, puberulent. Leaves oval to oblong-oval, 5-10 cm long, 2-4 cm wide, upper and lower surfaces glabrous, basally broadly cuneate, apically obtuse to rounded, the margins shallowly cuspidate-denticulate, strigil- lose, the lower third entire; petioles 2-5 mm long, strigillose. Capitulescences cymose-paniculate, 3- 6-headed; peduncles 3-6 cm long, bracteate. Ca- pitula radiate, 9-12 mm high, 10-11 mm wide; involucres campanulate; phyllaries 2-3 -seriate, subequal, herbaceous, the outer lanceolate to ob- lanceolate, 5-8 mm long, 1.5-2.5 mm wide, api- cally acute, ciliolate, the inner oblanceolate to nar- rowly rhombic-obovate, apically acute, ciliolate; paleae oblanceolate, ca. 8 mm long, apically sub- cucullate to truncate, fimbriate; ray florets ca. 8, the ligules oval to oblong, 14-20 mm long, ca. 5 mm wide, the tube ca. 4 mm long, villosulose; disc florets 10-30, the corollas cylindric-funnelform, ca. 5 mm long, the tube ca. 1 mm long, the lobes ca. 0.6 mm long. Achenes obconical, ca. 5 mm long, densely sericeous; pappus of 2 awns, ca. 4 mm long, persistent. FLOWERING (AND FRUITING) PERIOD— Decem- ber-March (March-May). DISTRIBUTION AND HABITAT (Fio. 26)— Scat- tered populations on dry, rocky slopes along the western Cordillera of the Andes from northern to central Peru (2,500-3,500 m). VERNACULAR NAMES— Carcarillo, sdmana, uno. REPRESENTATIVE SPECIMENS EXAMINED— PERU. An- cash: Bolognesi, ca. Chiquian, Cerrate 103 (USM), Fer- reyra 5668 (us, USM); Carhuaz, Infantes 1122 (LIL); Huaraz, 4 km S of Huaraz, Rio Santa Valley, Dillon el al. 3171 (BM, F, GH, HUT, MEXU, MO, NY, TEX, us, USM); Huaylas, Caraz, Ferreyra 14615 (us, USM); Recuay, Mar- ca, Richardson 2087 (BM, F, MO, TEX); Yungay, between Flourensia macrophylla is readily distinguished by its large oval or oblong-oval, regularly dentic- ulate leaves and small capitula with ca. 8 ray flo- rets. The size of the leaves and capitula vary; smallest individuals occur in the north and larger ones to the south. 1 6. Flourensia angustifolia (DC.) S. F. Blake, Contr. U.S. Natl. Herb. 20: 407. 1921. Figures 22, 26. Flourensia thurifera var. angustifolia DC, Prodr. 5: 592. 1836. TYPE: Peru, Junin, Tarma, J. Dombey 24 pro parte (lectotype, here designated, G-DC, IDC Microfiche 800. 952: I. 1!; isotype, B, destroyed; photograph of B specimen, F!). There appear to be two taxa in the first frame of the microfiche. The Dombey specimen to the right is clearly marked and is here chosen as the lectotype. DeCandolle listed Dombey, Haenke, and Nee in the protologue, but the last two collectors do not have representative material in the microfiche. Dombey's collection is labeled "Chile" in G-DC, but the B specimen was marked as from Tarma, unquestionably the origin of this plant. Shrubs to 2 (-3) m tall; branchlets resinous, red- dish brown. Leaves lanceolate to oblong-lanceo- late, 8-13 cm long, 1.5-2 cm wide, upper and lower surfaces glabrous, basally and apically acute to acuminate, the margins shallowly cuspidate with lower '/3 entire, strigillose; petioles 2-5 mm long, strigillose. Capitulescences cymose, 3-6-headed; peduncles 1-6.5 cm long, bracteate. Capitula ra- diate, 8-10 mm high, 8-15 mm wide; involucres hemispheric to campanulate; phyllaries 2-3-seri- ate, subequal, herbaceous, lanceolate to linear-lan- ceolate, 4-9 mm long, 1-2 mm wide, apically acute to attenuate, ciliolate; paleae oblanceolate, 9-12 mm long, apically acute to subcucullate; ray florets ca. 8, the ligules oblong to oval, 13-20 mm long, 5-8 mm wide, the tube ca. 5 mm long, villosulose; disc florets 30-40, the corollas cylindric-campan- ulate, 6-7 mm long, the tube ca. 1.5 mm long, the lobes 0.6 mm long. Achenes obconical, 6-8 mm long, densely sericeous; pappus of 2 awns, 3-5 mm long, persistent. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— Decem- ber-April (February-June). DISTRIBUTION AND HABITAT (Fie. 26)— Abun- DILLON: SYSTEMATIC STUDY OF FLOURENSIA 35 5mm 1cm FIG. 21. Flourensia macrophylla (from Macbride 2929, F). A, habit; B, capitulum; C, disc floret. 36 FIELDIANA: BOTANY 1 cm 2 cm FIG. 22. Flourensia angustifolia (from Killip & Smith 21792, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 37 dant on clay or serpentine soils within the inter- montane valleys of the Cordillera Central in cen- tral Peru (1,700-3,300 m). VERNACULAR NAMES— Aserijaeba, pfanca. REPRESENTATIVE SPECIMENS EXAMINED — PERU. Huanuco: Huanuco, near Huanuco, Kanehira 77 (F, GH). Junin: Tarma, Tarma, Cerro San Bartolome, Dillon & Rodriguez 449* (F, HUT, TEX, USM), Dillon & Turner 1317 (F, MO, TEX, USM); Tarma, Macbride & Featherstone 1018 (F, GH, us); between Acobamba and Tarma, Stork 10951 (F, uc); Acobamba, Woytkowski 54 (F). Flourensia angustifolia is distinguished by its narrowly oblong-lanceolate leaves with shallowly cuspidate margins and small capitula with ca. 8 ray florets. Its associates include Acacia, Opuntia, and Prosopis. 17. Flourensia peruviana Dillon, Ann. Missouri Dot. Gard. 68: 108. 1981. TYPE: Peru, Huan- cavelica, Huancavelica, Checcyancu, al 4 km E de Conaica, 3,000-3,500 m, 14 March 1971, O. Tovar 193 (holotype, us!; isotypes, F!, LP!, USM!). Figures 23, 26. Shrubs to 2 m tall. Leaves lanceolate to oblong- lanceolate, (5-) 7-10 (-12) cm long, (1-) 1.5-2 (- 3) cm wide, upper and lower surfaces glabrous, basally broadly cuneate, apically acute to obtuse, the margins entire, strigillose; petioles (2-) 4-8 (- 1 0) mm long. Capitulescences cymose-paniculate, 4-20-headed; peduncles 5-50 mm long, bracteate. Capitula radiate, ca. 10 cm high, 7-10 mm wide; involucres hemispheric; phyllaries 2-3-seriate, imbricate, herbaceous, the outer lanceolate, 2-3 mm long, 1-1.5 mm wide, apically acute, the inner elliptic-obovate, 3-5 mm long, ca. 1.5 mm wide, laterally chartaceous, apically acute; paleae oblan- ceolate, ca. 9 mm long, apically rounded, erose; ray florets 8-10, the ligules oblong to oval, 10-18 mm long, ca. 5 mm wide, the tube ca. 5 mm long, villosulose; disc florets 20-40, the corollas cylin- dric-campanulate, ca. 7 mm long, the tube ca. 1.5 mm long, the lobes ca. 0.5 mm long. Achenes obconical, ca. 10 mm long, sericeous; pappus of 2 awns, ca. 3 mm long, readily disarticulating. FLOWERING (AND FRUITING) PERIOD— Febru- ary-April (March-May). DISTRIBUTION AND HABITAT (Fio. 26)— Known from dry, rocky slopes in the quebradas associated with the Rio Mantaro in south-central Peru ( 1 ,700- 3,500 m). VERNACULAR NAMES— Chilca negra, yana-chil- ca. SPECIMENS EXAMINED— PERU. Ayacucho: Huaman- ga, La Mejorada to Ayacucho, KM 15, Ochoa 574 (GH); Huamanga, Chaquihuaycco, above Ayacucho, Tovar 5491 (USM); Huamanga, Chanchara, Rio Cachi, Tovar 5589 (SM), 5709 (USM). Huancavelica: Tayacaya, be- tween Izcuchaca and Mariscal Caceres, Tovar 1378 (LP, USM). Flourensia peruviana differs from F. polyce- phala in possessing much smaller phyllaries of the same shape. Its leaves are comparable in size and shape to those of F. angustifolia, but differ in hav- ing strictly entire margins. 18. Flourensia polycephala Dillon, Ann. Missouri Bot. Gard. 68: 106. 1981. TYPE: Peru, Cuzco, Calca, Pisac, April 1943, 3,000 m, F. Marin 231 (holotype, LIL!; isotype F!). Figures 24, 26. Shrubs to 4 m; branchlets puberulent. Leaves lanceolate to lance-elliptic, (8-) 10-12 (-14) cm long, 1.5-2.5 (-3) cm wide, upper and lower sur- faces glabrous, basally cuneate, apically acute or rarely obtuse, the margins entire, strigillose; pet- ioles 2-5 mm long. Capitulescences cymose-pa- niculate, 4-8-headed; peduncles (1-) 3-5 (-7) cm long, bracteate. Capitula radiate, 1 5-20 mm high, 10-15 mm wide; involucres hemispheric; phyl- laries 3-seriate, imbricate, herbaceous, the outer linear-lanceolate, (5-) 7-9 mm long, ca. 1 mm wide, apically attenuate, the inner rhombic, 8-9 mm long, 3-3.5 mm wide, laterally chartaceous, apically attenuate, ciliolate; paleae oblanceolate, ca. 9 mm long, apically acute to rounded, erose, ciliolate; ray florets 10-13, the ligules oblong, ca. 30 cm long, 5-6 mm wide, the tube ca. 5 mm long; disc florets 20-30, the corollas cylindric-campan- ulate, ca. 7 mm long, the tube ca. 1 mm long, the lobes ca. 0.5 mm long. Achenes obconical, 8-9 mm long, villous-sericeous; pappus of 2 awns, ca. 3 mm long, readily disarticulating. FLOWERING (AND FRUITING) PERIOD— January- April (March-May). DISTRIBUTION AND HABITAT (Fio. 26)— Known from dry, rocky slopes in the quebradas associated with the Rio Apurimac and Rio Urubamba in southeastern Peru (2,700-3,200 m). SPECIMENS EXAMINED— PERU. Apurimac: Grau, Or- opeza Valley, Vargas 9784 (F, uc). Cuzco: Calca, Hda. Urco, Vilcanota Valley, Vargas 683 (F, MO); Urubamba, ESE of Cuzco, Ellenberg 1000 (us); Huasao, Herrera 3098 (us); Urubamba, Lamallva 53 (LP); Rumichaca, Vargas 7597 (LIL); Chicon Canyon, Vargas 11053 (F, uc). 38 FIELDIANA: BOTANY 5 mm FIG. 23. Flourensia peruviana (from Tovar 193, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 39 FIG. 24. Flourensia polycephala (from Mann 231, F). A, habit; B, capitulum; C, disc floret. Flourensia polycephala differs from the closely related F. heterolepis (Bolivia) in having more nu- merous capitula in cymose capitulescences with generally shorter peduncles. It has longer phylla- ries and more ray florets than its nearest geograph- ical neighbor, F. peruviana. 19. Flourensia heterolepis S. F. Blake, Contr. Gray Herb. n.s. 54: 186. 1918. nom. nov. Figures 25, 26. Viguiera glutinosa Rusby, Mem. Torrey Bot. Club 4:211. 1895. TYPE: Bolivia, Cochabamba, Coch- abamba, 189 1, N. H. Bang 977 (holotype, NY!, pho- tograph F!; isotypes, BM!, GH!, MO!, us!). Non Flour- ensia glutinosa (Robinson & Greenman) S. F. Blake, Proc. Amer. Acad. 49: 374. 1913. Shrubs to 1 m tall. Leaves elliptic-lanceolate to oblong-ovate, 7.5-13 (-14.5) cm long, 1.4-2.5 cm wide, upper and lower surfaces strigillose to gla- brous, basally cuneate, apically acute to obtuse, the margins entire, strigillose; petioles 6-16 mm long. Capitulescences solitary to weakly cymose, 2-5-headed; peduncles (3-) 5-8 cm long, brac- teate. Capitula radiate, 15-20 mm high, 10-20 mm wide; involucres hemispheric; phyllaries 40 FIELDIANA: BOTANY 5mm I cm FIG. 25. Flourensia heterolepis (from Brooke 6220, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 41 — 5( •10 °o o- — 15 •20 0 50 100 200 ' — I 1 1 1 0 5O IOO 200 3OO 40O O Flourensia macrophylla ~jf F_. angustifolia •25 ^X —• heterolepis A £• polycephala 0 F_. peruviana 1 F. fiebrigii FIG. 26. Distribution of Flourensia angustifolia, F. fiebrigii, F. heterolepis, F. macrophylla, F. peruviana, and F. polycephala. 3-seriate, imbricate, the outer lanceolate, 7-9 mm long, 1-2 mm wide, apically acute, the inner rhom- bic-ovate, 8-10 (-11) mm long, (2-) 3-3.5 mm wide, laterally chartaceous, fimbriate, apically at- tenuate; paleae oblanceolate, ca. 8 mm long, api- cally rounded to cucullate, erose to fimbriate, sometimes cuspidulate; ray florets ca. 13, the lig- ules oblong, 15-25 mm long, 5-7 mm wide; the 42 FIELDIANA: BOTANY FIG. 27. Flourensia suffrutescens (from Dillon & Rodriguez 550, F). tube ca. 6 mm long, villosulose; disc florets 30— 50, the corollas cylindric-campanulate, ca. 6 mm long, the tube ca. 1 mm long, the lobes ca. 0.8 mm long. Achenes obconical, ca. 8 mm long, villous- sericeous, faces glabrescent; pappus of 2 awns, ca. 5 mm long, persistent or disarticulating. FLOWERING (AND FRUITING) PERIOD— Novem- ber-March (February-March). DISTRIBUTION AND HABITAT (FiG. 26)— Known from arid sites within the lower-montane, sub- tropical, thorny steppe associated with the Cor- dillera Real in western Bolivia (2,700-3,000 m). SPECIMENS EXAMINED— BOLIVIA. Cochabamba: Vila Vila, Brooke 6220 (F); above Arani, Cdrdenas 2416 (us); 50.3 km E of Cochabamba, Davidson 5050 (F); 11 km from Quillacollo, King & Bishop 7559 (F); 19 km from Tolata, King & Bishop 7585 (F). Flourensia heterolepis is distinguished from F. polycephala, its closest relative, by its longer pe- duncles and fewer capitula. Its leaf size and shape are variable; some individuals have small leaves that approach those ofF.fiebrigii, a species readily distinguished by its smaller capitula, phyllaries, and ray florets. Associates of F. heterolepis within the thorny steppe include Acacia, Carica, Cleis- tocactus, Dodonaea, Nicotiana glauca, Schinus, and Solanum. 20. Flourensia suffrutescens (R. E. Fries) S. F. Blake, Proc. Amer. Acad. Arts 49: 376. 1913. Figures 27, 30. Encelia suffrutescens R. E. Fries, Nov. Act. Soc. Sci. Upsal. IV. 1: 83. 1903. TYPE: Argentina, Jujuy, DILLON: SYSTEMATIC STUDY OF FLOURENSIA 43 Moreno, rocky slope, 3,600 m, 16 Dec. 1901, R. E. Fries 926 (holotype, UPSV, not seen; isotype, us!). Subshrubs to 40 cm tall; stems decumbent-as- cending, pilose, gray. Leaves narrowly lanceolate to oblong, 2-8.5 cm long, 8-18 mm wide, upper and lower surfaces pilose, basally cuneate, apically acute to acuminate, the margins entire; petioles 1- 3 (-5) mm long, pilose. Capitulescences solitary, terminal; peduncles 8-1 1 cm long, densely pilose, distally canescent, bracteate. Capitula radiate, ca. 12 mm high, 12-18 mm wide; involucres hemi- spheric; phyllaries 2-seriate, equal, the outer ob- long-lanceolate to ovate-lanceolate, subcanescent- pilose, apically attenuate, the inner rhombic-ob- ovate, sparsely pilose, apically acuminate, all ca. 1 1 mm long, ca. 2.5 mm wide, herbaceous; paleae oblanceolate, 8-10 mm long, apically obtuse to truncate; ray florets 9-15, the ligules linear-oblong to elliptic, 17-32 mm long, 4-10 mm wide, the tube ca. 5 mm long, sericeous; disc florets ca. 50, the corollas cylindric, ca. 5 mm long, the tube ca. 1 mm long, the lobes ca. 0.7 mm long, spiculifer- ous. Achenes obconical, ca. 6 mm long, densely sericeous; pappus of 2 awns, equal 3-4 mm long, persistent. Chromosome number: n — 18. FLOWERING (AND FRUITING) PERIOD— February (March). DISTRIBUTION AND HABITAT (Fio. 30)— Known from scattered populations in the altiplano of Salta and Jujuy in northwestern Argentina (2,500-3,600 m). SPECIMENS EXAMINED— ARGENTINA. Salta: Rosa- rio de Lerma, Quebrada de Tastil, Las Cuevas, Cabrera 9002 (F); Cachipampa, Cabrera 22040 (LP); Puerta Tas- til, Cabrera 22398 (LP); Cachipampa, 1 5 km W of Piedra del Molino, Dillon & Rodriguez 550* (F, MO, NY, TEX). Flourensia suffrutescens is distinguished by its small habit and large capitula with subcanescent- pilose phyllaries that equal or overtop the disc. At the Cachipampa locality, it is associated with Lar- rea at the lower end of its range (ca. 2,500 m) and becomes dominant at higher elevations and is often associated with Baccharis boliviensis, Cassia, and Senecio. 21. Flourensia macroligulata Seeligmann, Lilloa 30: 113. 1960. TYPE: Argentina, Jujuy, Volcan, Loma de las Lagunas, 1 5 Feb. 1 924, R. Schreiter 2663 (holotype, LIL!). Figures 28, 30. Rounded shrubs to 1.5m tall; stems decumbent to ascending; branchlets sparsely sericeous. Leaves elliptic to obovate-elliptic, 7-13 cm long, 2.5-6 cm wide, upper and lower surfaces sparsely seri- ceous, basally cuneate to rounded, apically acute to rounded, the margins entire; petioles 5-10 mm long, the upper leaves subsessile. Capitulescences solitary, terminal; peduncles 4-10 cm long, seri- ceous, bracteate. Capitula radiate, 1 8-20 mm high, ca. 25 mm wide; involucres hemispheric; phyllar- ies 2-3-seriate, all lanceolate-elliptic, the outer overtopping the disc, 20-22 mm long, ca. 5 mm wide, overtopping the disc, the inner ca. 18 mm long, ca. 4 mm wide, all apically acute to obtuse, sericeous; paleae obovate, ca. 1 3 mm long, apically acute to truncate, sericeous; ray florets 1 3-2 1 , the ligules oblong-elliptic, 25-50 mm long, 4-7 mm wide, the tube 5-9 mm long, sericeous; disc florets 50-75, the corollas campanulate, ca. 5 mm long, the tube ca. 1 mm long, the lobes ca. 0.8 mm long, sparsely pilose. Achenes obconical, ca. 1 1 mm long, densely sericeous; pappus of 2 awns, ca. 3 mm long, persistent. FLOWERING (AND FRUITING) PERIOD— January- February (February-March). DISTRIBUTION AND HABITAT (FiG. 30)— Known from extensive collections on the rocky, over- grazed slopes in the vicinity of the Laguna de Vol- can, Jujuy, and is represented by one collection each from Tan, Tucuman, and Tilcara, Jujuy, Ar- gentina (2,000-3,000 m). REPRESENTATIVE SPECIMENS EXAMINED— ARGEN- TINA. Jujuy: Volcan, Cabrera 12187 (LP), Cabrera & Frangi 20649 (LP), Cabrera & Marchionni 12945 (us), Castillon 9519 (LIL); ca. 41 km NE of San Salvador de Jujuy, Dillon & Rodriguez 553 (BM, F, GH, MO, NY, TEX, USM); Tilcara, Venturi 7402 (us). Tucuman: Tan, Sierra del Cajon, Venturi 6284 (us). Flourensia macroligulata is distinctive with its large leaves and large capitula with the largest lig- ules to be found within the genus. In the vicinity of the type locality, individuals occur on very steep walls of the upper reaches of arroyos. The adjacent hillsides are overgrazed and deep erosional areas are prevalent. A local goat herder said that the goats would browse this species and have destroyed all but those individuals in inaccessible locations. I estimate the population there to be of no more than a few hundred plants. At lower elevations, the rocky slopes are covered with dense cushions of Bromeliaceae and low Cac- taceae. 44 FIELDIANA: BOTANY 5mm 1cm FIG. 28. Flourensia macroligulata (from Dillon & Rodriguez 553, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 45 2cm FIG. 29. Flourensia tortuosa (from Dillon & Rodriguez 511, F). A, habit; B, capitulum; C, disc floret. 46 FIELDIANA: BOTANY -23 17' Tropic of Capricorn •25 Flourensia tortuosa •^ Flourensia macroligulata Q Flourensia suffrutescens O Flourensia hirta % Flourensia blakeana B Flourensia leptopoda •30 32 FIG. 30. tortuosa. Distribution of Flourensia blakeana, F. hirta, F. leptopoda, F. macroligulata, F. suffrutescens, and F. 22. Flourensia tortuosa Griseb. Abh. Konigl. Ges. Wiss. Gottingen 19: 184: 1874. TYPE: Argen- tina, Catamarca, fields between Belen and Ya- cutula, 24 Jan. 1872, P. G. Lorentz 659 (holo- type, GOET!; isotype, CORD!, photograph, F!). Figures 29, 30. Shrubs to 2 m tall; stems ascending; branchlets sparsely sericeous. Leaves lanceolate to oval, (3-) 5-9 (-14) cm long, 1.5-3.5 (-5) cm wide, upper and lower surfaces strigillose, basally cuneate to rounded, apically acuminate to obtuse, the mar- gins entire, strigillose; petioles 3-17 mm long. Capitulescences solitary or weakly cymose, 2-3- headed; peduncles 1-4 cm long, puberulent, brac- teate. Capitula radiate, 10-15 mm high, 10-20 mm wide; involucre hemispheric, often subtended by calyculate bracts; phyllaries 2-3-seriate, equal to subequal, broadly ovate to oblong-lanceolate, (5-) 7-15 mm long, (2-) 3-7 mm wide, herba- ceous, apically acute to attenuate, ciliolate; paleae oblanceolate, ca. 10 mm long, apically acute to truncate, erose-ciliolate; ray florets ca. 10, the lig- ules broadly oblong, 18-30 mm long, 7-10 mm DILLON: SYSTEMATIC STUDY OF FLOURENSIA 47 wide, the tube ca. 8 mm long, glabrous; disc florets 30-50, the corollas cylindric, 4-6 mm long, the tube ca. 1 mm long, the lobes ca. 0.7 mm long. Achenes obconical, 5-6 mm long, the margins se- riceous, the faces sericeous to glabrescent; pappus of 2 awns, ca. 3.5 mm long, often bifid, persistent or disarticulating. FLOWERING (AND FRUITING) PERIOD— January- March (February-April). DISTRIBUTION AND HABITAT (Fio. 30)— Found on coarse sand in arroyos of upper bajadas be- tween the Sierras de Zapata, de Anconjuija, and de Belen in south-central Catamarca; and scat- tered populations in central Salta and Tucuman, Argentina (1,200-3,100 m). REPRESENTATIVE SPECIMENS EXAMINED— ARGEN- TINA. Catamarca: Andalgala, Cabrera 1023 (LP, us); Cuesta de Mina Capillitas, Cabrera et al. 14140 (LP, NY); Tinogasta, Cuesta de Zapata, Tinogasta to Helen, Ca- brera et al. 16736 (LP); Londres, Cabrera 18116 (LP); Punta de Balasto, Cabrera 21807 (LP); 4 km N of An- dalgala. Cantino 670 (ARIZ); Andalgala. Cuesta de La Chilca, Cristoba 1477 (LIL, uc); 10 km SW of Londres, Dillon & Rodriguez 511 (F, GH, MO, NY, TEX, USM); Cerro Duraznos, Job 1380 (LP); El Candado, Jorgensen 1273 (GH, LIL, MO, si, uc, us); Cerrillos, Sierra de Aconquija, Peirano s.n. (GH, LIL). Salta: Cafayate, Rio Lorohausi, Hayward2055 (LIL); Cafayate, El Alisal, Cerro del Cajon, Rodriguez 1341 (A, LIL, si, us); Rosario de Lerma, Nev- aro to Castillo, Venture 9271 (us). Tucuman: Valle Tan, La Banda, Castilldn s.n. (A, LIL). Flourensia tortuosa has variable leaves, seem- ingly depending upon available moisture in re- spective habitats. Its phyllaries are also variable; individuals from Tucuman and Salta have narrow, oblong-lanceolate phyllaries and those surround- ing the Bolson de Pipanaco, Catamarca have wid- er, ovate phyllaries. Its associates include Cerci- dium, Heliotropium, Larrea, and Senecio. 23. Flourensia oolepis S. F. Blake, Contr. U.S. Natl. Herb. 20: 403. 1921. TYPE: Argentina, Cordoba, Cuesta de La Oyada, Sierra Achala, 22 March 1876, G. Hieronymus s.n. (holotype, B, destroyed; lectotype, here designated, frag- ment GH!; photograph of B specimen, F!, GH!). Figures 31, 38. Flourensia grindelioides S. Moore, J. Bot. 64: 192. 1926. TYPE: Argentina, San Juan, s.d., Ms. Wright s.n. (holotype, BM!; isotype MO!, isotype fragments GH!, us!). Shrubs to 3 m tall, stems ascending, the bark brown, fissured. Leaves elliptic to elliptic-lanceo- late, 5.5-8.5 cm long, 2-3.2 cm wide, upper and lower surfaces glabrous, basally and apically acute, the margins entire or with 4-6 teeth apically; pet- ioles 5-10 mm long. Capitulescences solitary or weakly cymose, 2-3-headed; peduncles 4-6 cm long, bracteate. Capitula radiate, 15-18 mm high, 15-25 mm wide; involucres hemispheric; phyl- laries 3-4-seriate, imbricate, the outer broadly ovate, the inner gradually more oblong, all 5-6 mm long, 2.5-4 mm wide, subherbaceous, apically acute to attenuate, ciliolate; paleae oblanceolate, ca. 7 mm long, apically subtruncate to cucullate; ray florets 12-16, the ligules oblong, 12-28 mm long, 3-8 mm wide, the tube 4-5 mm long, seri- ceous; disc florets ca. 50, the corollas cylindric, 5- 6 mm long, the tube ca. 1 mm long, the lobes ca. 0.5 mm long. Achenes obconical, 5-8 mm long, sericeous; pappus of 2 awns, 4-5 mm long, basally strongly ampliate and deeply lacerate, frequently united into a lacerate corona, persistent. Chro- mosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— Septem- ber-March (January-March). DISTRIBUTION AND HABITAT (Fio. 38)— Abun- dant in the regions west of the Sierras de Las Co- mechingones and de Cordoba in northwestern Cordoba and the Sierra de San Luis, northeastern San Luis, Argentina (1,000-2,000 m). VERNACULAR NAMES— Chilca gomosa. REPRESENTATIVE SPECIMENS EXAMINED— ARGEN- TINA. Cordoba: La Vina, Bart let t 20615 (GH, MICH, si, TEX, us); San Javier, Bridarolli 1006 (LP); Sierra de Po- cho, Los Tuneles, Burkart 20864 (LP); Los Cocos, Ca- brera 7 (GH, LP); 2 km S of Charbonier, Dillon & Ariza 567* (F, MO, TEX, USM); Sierra Grandes, Chacras, Hun- ziker 2737 (LIL, si); Los Terrenes, Ongamira, Luti 4927 (CORD, LP); Capilla del Monte, O'Donell & Rodriguez 356 (F, LIL); Arroyo Saltos Blancos, Solomon & Solomon 4115 (F, MO); La Cumbre, Sola 401 (LIL); Villa Dolores, Varela 444 (A, LIL); Yacanto, Vattuone 17 (si); San Mar- cos, Villafane289(iM-). San Luis: Merlos, Piedra Blanca, Burkart 13935 (si); Nogoli, Gez 109 (si); Sierra de Los Comechingones, 4 km E of Merlo, Conrad & Dietrich 2490 (F, MO); El Volcan to Potero de Los Funes, Nicora 4253 (si); Sololosta, Vignati 168 (LP). Flourensia oolepis is distinguished by its short, broadly ovate phyllaries, 12-16 ray florets, and achenes with the pappus awns united basally to form a corona. 24. Flourensia fiebrigii S. F. Blake, Bot. Jahrb. Syst. 54: 47. 1916. TYPE: Bolivia, Tarija, slope, 48 FIELDIANA: BOTANY 5mm Icm 2cm FIG. 31. Flourensia oolepis (from Conrad 2490, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 49 I cm FIG. 32. Flourensia fiebrigii (from Meyer s.n., F). A, habit; B, capitulum; C, disc floret. 50 FIELDIANA: BOTANY summit of pass, near Paicho, W of Tarija, 3,200 m, 5 Feb. 1904, K. Fiebrig 3050 (holotype, B, destroyed; lectotype, here designated, F!; iso- types BM!, GH!, MO!, si!, us!). Figures 26, 32. Shrubs to 50 cm tall; stems decumbent to as- cending; branchlets brown to gray, puberulent. Leaves lanceolate to oblanceolate, 3.5-5 (-8) cm long, (5-) 7-14 (-20) mm wide, upper and lower surfaces hispid-pilose to glabrescent, basally and apically acute to acuminate, the margins entire, strigillose; petioles 2-6 mm long. Capitulescences solitary or weakly cymose, 2-3 -headed; peduncles 1-5 cm long, hispid-pilose. Capitula radiate, 8-9 mm high, 7-9 mm wide; involucres campanulate; phyllaries 2-3-seriate, subequal, the outer linear- lanceolate to lance-ovate, apically acute, the inner rhombic-ovate, apically attenuate, all 4-6 (-8) mm long, 1-2 mm wide, densely to sparsely ciliolate, hispid to glabrescent; paleae oblanceolate, 6-7 mm long, apically acute to truncate, lacerate, glabrous to hirsute; ray florets 7-10, the ligules oblong-oval, 11-16 mm long, 6-8 mm wide, the tube 3-4 mm long, sericeous; disc florets 10-15 (-25), the co- rollas campanulate to narrowly salverform, 3-4 mm long, the tube 0.5-0.8 mm long, the lobes 0.5-0.7 mm long, spiculiferous or glabrous. Achenes obconical, 4-6 mm long, sericeous; pap- pus of 2 (-3) awns, 2-2.5 mm long, basally am- pliate, lacerate, persistent. FLOWERING (AND FRUITING) PERIOD— Febru- ary-March (March). DISTRIBUTION AND HABITAT (Fio. 26)— Known from dry, rocky slopes and bajadas from the cen- tral Cordillera Real in Bolivia, and south to the Quebrada de Humahuaca in central Jujuy, Argen- tina (2,700-3,700 m). REPRESENTATIVE SPECIMENS EXAMINED— ARGEN- TINA. Jujuy: Maimaria, Hualchin, Budin 79(uL); Sierra de Zenta, Budin 7446 (LIL, us); Tilcara, Quebrada del Chorro, Cabrera 7672 (LP, us); Huacalera, Quebrada de La Huerta, Cabrera 12051 (LP, us); Purmamarca, Que- brada de Huachichocana, Cabrera 15022 (LP); Yavi, Abra de Yavi, Cabrera 15337 (LP); Quebrada del Yocordite, Cabrera 21262 (LP); Quebrada del Rio Guasamayo, Ca- brera & Solbrig 17031 (LP); Garganta del Diablo, Ca- brera et al. 13932 (LP); Tilcara, Cabrera et al. 13285 (LP); Yavi, 1 6 km E of La Quiaca, Dillon & Rodriguez 579 (F, MO, TEX, USM); Tilcara, Dillon & Rodriguez 587 (F, TEX); La Quiaca, Meyer s.n. (F, GH, LIL); Pena Alta, Venturi 4910 (F, GH, LIL, si, TEX, uc, us); 5 km NE of Humahuaca, West 6318 (MO). BOLIVIA. Potosi: Atocha to Quechisla, West 6100 (GH, uc). Flourensiafiebrigii is distinguished by its small, hispid-pilose leaves and small capitula with 7-10 ray florets. Leaf size, degree of pubescence, and growth form are quite variable. Individuals from the type locality are robust shrubs with wide leaves and sparse pubescence; to the southwest, individ- uals are smaller and the leaves are quite pubescent. With continued study, these forms may warrant formal taxonomic recognition. Its associates in- clude Baccharis, Cassia, Hoffmanseggia, Hyme- noxys, Parthenium, and Trichocereus. 25. Flour ensia blakeana Dillon, Ann. Missouri Bot. Gard. 68: 108. 1981. TYPE: Argentina, Tucu- man, KM 95-105 on Ruta 307, between Amai- cha del Valle and Tan del Valle, 2,900-3,000 m, 22 Feb. 1973, M. Dillon & E. Rodriguez 560* (holotype TEX!; isotypes, BM!, F!, HUT!, LP!, MO!, NY!, USM!). Figures 30, 33. Shrubs to 1 m tall; stems ascending, the bark gray to black. Leaves narrowly oblong-elliptic, ( 1 5-) 20-35 (-47) mm long, (3-) 4-8 (-11) mm wide, upper and lower surfaces sparsely strigillose, ba- sally attenuate, apically acute, the margins entire, strigillose; petioles 1-3 mm long. Capitulescences cymose, 2-4-headed; peduncles 1-4 cm long, sparsely strigillose. Capitula radiate, 6-11 mm high, (5-) 7-1 0 (-1 4) mm wide; involucres campanulate; phyllaries 2-3-seriate, subequal, the outer linear- lanceolate, (3-) 4-6 mm long, 0.8-1 mm wide, apically attenuate, black, strigillose, the inner nar- rowly rhombic, 5-6 (-7) mm long, apically atten- uate; paleae oblanceolate, 5-6 mm long, apically obtuse; ray florets ca. 8, the ligules oblong-oval, 10-24 mm long, 5-8 mm wide, the tube 3-4 mm long, pubescent to glabrous; disc florets ca. 25, the corollas cylindric-campanulate, 4-5 mm long, the tube ca. 1 mm long, the lobes 0.6-0.8 mm long. Achenes obconical; pappus of 2 awns, 2.0-3.5 mm long, the bases ampliate, persistent. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— January- March (March). DISTRIBUTION AND HABITAT (Fio. 30)— Fre- quent on sand and gravel of lower bajadas in the arid quebradas in the Cordillera Oriental of north- western Tucuman and adjacent eastern Catamar- ca, Argentina (1,800-3,000 m). VERNACULAR NAME— Viscol. SPECIMENS EXAMINED— ARGENTINA. Catamarca: Santa Maria, Torollaco, Reales 1056 (LIL); Pafaquillo, DILLON: SYSTEMATIC STUDY OF FLOURENSIA 51 5mm' 2cm I cm FIG. 33. Flourensia blakeana (from Dillon & Rodriguez 560, F). A, habit; B, capitulum; C, disc floret. Reales 1702 (LIL). Tucuman: ca. 25 km NW of Tafi de Valle, Bacon & Bohnstedt 77 (TEX); Cuesta del Infier- nillo, Cabrera & Frangi 20763 (LP); Divisadero, Cafay- ete-Tafi del Valle, Carenzo 1358 (LIL); Tafi, KM 95, Los Cardones, camino del Infiernillo a Amaicha, Legname & Vervoost 34 (NY); Machorastroja, Schreiter 1311 (LIL); Amaicha to Santa Maria, Schreiter 5636 (A, LIL); Las Areas, Schreiter 5637 (A, LIL); Quebrada del Chorro, Venturi 4110 (LIL, us). Flourensia blakeana is a frequent element of the xeric formation in the Cuesta del Infiernillo. It most closely resembles F. fiebrigii and is distin- guished from that species by its smaller leaves and narrower phyllaries. It is ecologically isolated from its nearest geographic neighbor, F. riparia, which occurs below 2,000 m in eastern Tucuman. 52 FIELDIANA: BOTANY I cm 5mm FIG. 34. Flourensia hirta (from Dillon & Rodriguez 471, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 53 26. Flourensia hirta S. F. Blake, Contr. U.S. Natl. Herb. 20: 402. 1921. TYPE: Argentina, La Rio- ja, vicinity of Los Corrales, Sierra Famatina, 7 Feb. 1897, G. Hieronymus & G. Niederlein 635 (holotype, B, destroyed; lectotype, here desig- nated, fragment GH!; photograph of B specimen, F!, GH!). Figures 30, 34. Shrubs to 1.5 m tall; stems ascending; branch- lets dark brown, hirsutulose. Leaves 3-6.5 (-7.5) cm long, 5-10 (-12) mm wide, upper and lower surfaces hirsutulose-strigillose, basally and api- cally attenuate, the margins entire, strigillose; pet- ioles 1-5 mm long. Capitulescences cymose, 2-4- headed; peduncles 1-6 cm long, hirsutulose. Ca- pitula radiate, ca. 10 mm high, ca. 8 mm wide; involucres cylindric-campanulate; phyllaries 2-se- riate, subequal, the outer linear to lanceolate, strig- illose to hirsutulose, the inner narrowly ovate-lan- ceolate, all apically attenuate, (5-) 6-10 (-13) mm long, 1-1.5 mm wide; paleae oblanceolate, ca. 6.5 mm long, apically obtuse to acute; ray florets 5- 8, the ligules oblong, 8-20 mm long, 3-8 mm wide, the tube ca. 5 mm long, puberulent, disc florets ca. 25, the corollas cylindric-campanulate, ca. 4 mm long, the tube ca. 0.5 mm long, the lobes ca. 0.5 mm long. Achenes obconical, 4-5 mm long, the margins sericeous, the faces glabrescent; pap- pus of 2 awns, 3-4 mm long, persistent. Chro- mosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— January- March (February-April). DISTRIBUTION AND HABITAT (FiG. 30)— Fre- quent on rocky rubble and coarse sand of bajadas and arroyos in dry quebradas associated with the Pre-Cordillera of northwestern La Rioja and west- ern Catamarca, Argentina (1,500-2,000 m). SPECIMENS EXAMINED— ARGENTINA. Catamarca: La Coipita, Castellanos s.n. (LP); road to San Francisco, KM 150-160, O'Donell & Meyer 5072 (LIL); Tinogasta to Chile road, KM 85, O'Donell & Meyer 5095 (LIL); Val- lecito to Agua Negra, Schreiter 6300 (A, LIL); Cachiyayo to Puerta Negra, Schreiter 6398 (LIL); Las Angosturas, Rio Chaschuil, Vervoorst 3150 (LIL); Caspinchango, Reales 1548 (LIL). La Rioja: El Zaguan, Cabrera 18048 (HUT, LP); Famatina to La Aguadita, Cabrera 18063 (HUT, LP); 1 km E of Puerto Alegre, Dillon & Rodriguez 471* (BM, F, MO, NY, TEX, USM); Fumes Chico, Quebrada Rio Bonete, Hunziker 2225 (LP, MO); 19 km S of Angulos, Hunziker &Andrada 9544 (F, USM, TEX); Valle Hermoso, La Pampa to Casa de Quincho, Hunziker & Caso 4260 (LP); Sierra de Famatina, Mesada de Los Pocito, Kra- povickas & Hunziker 5179 (LP); Campanas, Rojas Paz s.n. (LIL); between Angulos and Campanas, Vervoorst 650 (LIL). Flourensia hirta is distinguished by its narrowly lanceolate, strigillose-hirsutulose leaves and green, strigillose to hirsutulose phyllaries. Associates in- clude Atamisquea, Bulnesia, Larrea, Proustia, Se- necio, and Trichocereus. 27. Flourensia niederleinii S. F. Blake, Contr. U.S. Natl. Herb. 20: 404. 1921. TYPE: Argentina. La Rioja, Cuesta de Miranda, Sierra Famatina, 1 0 March 1 879, G. Hieronymus & G. Niederlein 876 (holotype, B, destroyed; lectotype, here des- ignated, fragment, GH!; photograph of B speci- men, F!, GH!). Figures 35, 38. Shrubs to 1 m tall; stems ascending; branchlets hirsutulose. Leaves ovate to lanceolate (2-) 3.5- 4.5 (-6.8) cm long, 1.1-2.4 cm wide, upper and lower surfaces strigillose, basally cuneate to trun- cate, apically acute, the margins entire, strigillose; petioles 5-10 mm long, hirsutulose. Capitules- cences cymose, 2-4-headed; peduncles 2-4 cm long. Capitula radiate, ca. 10 mm high, ca. 10 mm wide; involucres hemispheric; phyllaries 2-seriate, subequal, herbaceous, hirsutulose, the outer lin- ear-lanceolate to linear-spathulate, apically acute, the inner ovate-lanceolate, apically attenuate, all 5-7 mm long, ca. 1.5 mm wide; paleae oblanceo- late, ca. 7 mm long, apically subacute to rounded; ray florets ca. 8, the ligules elliptic, ca. 18 mm long, ca. 8 mm wide, the tube ca. 5 mm long, hirsutulose; disc florets ca. 30, the corollas cylin- dric ca. 5 mm long, the tube ca. 0.6 mm long, the lobes ca. 1 mm long. Achenes obconical, ca. 5 mm long, the margins sericeous, the faces glabrescent; pappus of 2 awns, 3-4 mm long, persistent, basally ampliate, deeply lacerate. Chromosome number: n= 18. FLOWERING (AND FRUITING) PERIOD— January- March (February-March). DISTRIBUTION AND HABITAT (FiG. 38)— Fre- quent on well-drained, sandy and gravelly soils from the southern Sierra de Famatina in the vi- cinity of the Cuesta de Miranda and east to near Chilecito, La Rioja, Argentina (1,600-2,100 m). VERNACULAR NAME— Engordadora. SPECIMENS EXAMINED— ARGENTINA. La Rioja: be- tween Chilecito and Famatina, Cabrera 18071 (HUT, LP); Cuesta de Miranda, 9 km E of Los Tambillos, Dillon & Rodriguez 475* (BM, F, MO, NY, TEX, USM); 10 km E of Cuesta de Miranda, ca. 24 km SW of Chilecito, Dillon & Rodriguez 478* (F, HUT, MO, TEX); Cuesta de Miranda, 54 FIELDIANA: BOTANY Icm FIG. 35. Flourensia niederleinii (from Dillon & Rodriguez 475. F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 55 Frenguelli 512 (LIL, LP); Sierra de Famatina, Cuesta de Miranda, Hunziker & Caso 4337 (LP). To the west of Chilecito, populations have more nar- rowed leaves with cuneate bases. These are represented by the following collections: ARGENTINA. La Rioja: Los Tallas, W of Chilecito, Cabrera & Solbrig 16681 (LP); La Higuera, Falcdn & Castellanos 3667 (LP); Mina de Oro, Meyer 4084 (F, GH, LIL, si); Las Manza, Finca Los Bordos, Okada 2695 (LP); Guauchin, Venturi 7799 (A, BM, GH, MO, SI, US). Flourensia niederleinii is distinguished from its nearest geographical neighbor, F. hirta, by its wid- er leaves with rounded or truncate bases and ob- vious petioles. Its associates include Baccharis, Parthenium, Prosopis, Proustia, and Trichocereus. 28. Flourensia riparia Griseb., Abh. Konigl. Ges. Wiss. Gottingen 24: 196. 1879. TYPE: Argen- tina. Salta, passage of the Rio Turamento, Feb. 1873, G. Hieronymus & P. G. Lorentz 268 (ho- lotype, GOET!; isotypes, CORD!, F!, GH!, NY!, si!, us!). Figures 36, 38. Helianthus riparia (Griseb.) Kuntze, Rev. Gen. PI. 3: 157. 1898. Shrubs to 2 m tall; stems ascending; branchlets puberulent. Leaves oblong-lanceolate to elliptic- ovate, 6-14 cm long, 1.5-5 cm wide, upper and lower surfaces glabrous, basally acute, apically acute to acuminate, the margins entire, strigillose; pet- ioles 3-8 mm long. Capitulescences cymose-pan- iculate, 3-7-headed; peduncles 3-5.6 cm long, bracteate. Capitula radiate, ca. 1 1 mm high, ca. 10 mm wide; involucres campanulate; phyllaries 3-seriate, subequal, herbaceous, the outer lance- subulate, 4-5 mm long, ca. 2 mm wide, the inner lance-ovate, 6-7 mm long, 1.5-2 mm wide, all apically attenuate, ciliolate; paleae oblanceolate, ca. 7 mm long, apically obtuse to rounded; ray florets 7-10, the ligules oblong to oval, 1 5-20 mm long, ca. 4 mm wide, the tube ca. 5 mm long, glabrous; disc florets 25-40, the corollas cylindric, ca. 5 mm long, the tube ca. 0.8 mm long, the lobes ca. 0.6 mm long. Achenes obconical, 6-7 (-9) mm long, the margins sericeous, the faces glabrescent; pappus of 2 awns, 3-4 mm long, persistent. Chro- mosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— January- March (February-April). DISTRIBUTION AND HABITAT (FiG. 38)— Known from quebradas in the mountains of eastern Jujuy and south to Catamarca, east-central Salta, and northern Tucuman, Argentina (500-2,000 m). REPRESENTATIVE SPECIMENS EXAMINED— ARGEN- TINA. Catamarca: Del Alto, Balcozna, Venturi 7169 (F). JUJUY: Santa Barbara, Cachipunco, Cabrera et al. 17382 (LP); between Santa Clara and El Fuerte, Abra de Los Morteros, Fabris et al. 5206 (LP). Salta: Rosario de Ler- ma, Chorrillos, Cabrera 7927 (GH, LP, us); Chicoana, Quebrada Escoipe, Cabrera et al. 21994 (LP); La Vina, Osma, Cabrera & Marchionni 13051 (LP); Escoipe to base of Cuesta de Obispo, Dillon & Rodriguez 538* (F, MO, TEX); Coronel Moldes, Hunziker 1146 (LP); Gua- chipas, Alemania, Arroyo Las Pavas, Job 1518 (LP, us); Guachipas to Pampa Grande, Meyer 21858 (LIL); El Na- ranjo, O'Donell 5330 (LIL, TEX, us); Candelaria, Un- quillo, Schreiter 94 (A, LIL); Pampa Grande, Spegazzini 11616 (LP); Candelaria, Venturi 3708 (LIL, si, us). Tu- cuman: Tranchas, ca. 25 km N of San Miguel de Tu- cuman, Dillon & Rodriguez 537* (BM, F, HUT, MO, NY, TEX, USM); Burruyacu, Sierra Nogalito, Krapovickas & Legname 10897 (LIL); Rio Nio to Alto Medina, Legname & Cuezzo 4669 (LIL); Barrancas, Vipos, Lillo 3941 (LIL). Flourensia riparia is distinguished from F. cam- pestris, its closest relative, by its larger strictly en- tire leaves and greater number of ray florets. Its associates include Acacia, Cercidium, Opuntia, Prosopis, and Schinopsis. 29. Flourensia campestris Griseb., Abh. Konigl. Ges. Wiss. Gottingen 19: 184. 1874. TYPE: Ar- gentina, Cordoba, abundant in field SE of Cor- doba, 1 87 1 , P. G. Lorentz 245 (holotype, GOET!; isotype, CORD!, photograph, F!; isotype frag- ment, GH!). Figures 37, 38. Helianthus campestris (Griseb.) Kuntze, Rev. Gen. PI. 3: 157. 1889. Shrubs to 2 m tall; stems erect, reddish brown. Leaves lanceolate to ovate, 5-9 cm long 1.3-3.4 cm wide, upper and lower surfaces glabrous, ba- sally cuneate to rounded, apically acuminate, the margins with slight denticulations (rarely entire), strigillose; petioles (3-) 5-13 mm long. Capitu- lescences cymose-paniculate, 5-15-headed; pe- duncles 8-25 mm long, bracteate, puberulent. Ca- pitula radiate, ca. 8 mm high, ca. 5 mm wide; involucres cylindric-campanulate; phyllaries 2-se- riate, subequal, lanceolate to ovate-lanceolate, 4- 5 mm long, ca. 1 mm wide, apically attenuate; paleae oblanceolate, ca. 8 mm long, apically ob- tuse to truncate; ray florets 5-8; the ligules oval to oblong-oval, 7-10 mm long, 3-4.5 mm wide, the tube ca. 4 mm long, villosulose; disc florets 56 F1ELDIANA: BOTANY 2cm l cm B FIG. 36. Flourensia riparia (from Venturi 7169, F). A, habit; B, capitulum; C, disc floret. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 57 5mm 2cm FIG. 37. Flourensia campestris (from Dillon & Rodriguez 451, F). A, habit; B, capitulum; C, disc floret. 58 FIELDIANA: BOTANY •23" 27' Tropic of Capricorn D Flourensia riparia 0 Flourensia campestris A Flourensia niederleinii •fa Flourensia oolepis 30 •32 FIG. 38. Distribution of Flourensia campestris, F. niederleinii, F. oolepis, and F. riparia. 14-20, the corollas cylindric, ca. 5 mm long, the tube ca. 0.5 mm long, the lobes ca. 0.8 mm long. Achenes obconical, 5-6.5 mm long, the margins sericeous, the faces glabrescent; pappus of 2 awns, ca. 3.5 mm long, persistent. Chromosome num- ber: n= 18. FLOWERING (AND FRUITING) PERIOD— Decem- ber-February (February-March). DISTRIBUTION AND HABITAT (Fio. 38)— Known from arid sites within the Sierra de Cordoba in northeastern Cordoba, Sierras de Ambato and Gracinana in southeastern Catamarca, and the Sierra de Guasayan in southeastern Santiago del Estero, Argentina (500-1,000 m). VERNACULAR NAME— Chilca. REPRESENTATIVE SPECIES EXAMINED— ARGENTINA. Catamarca: Ambato, 1 km S of El Rodeo, Araque & Barkley 19Ar591 (us); El Crest6n, Castilldn 1201 (LIL); Capital, Castilldn 1202 (A); La Brea, Quebrada del Tala, Castilldn 1203 (LIL); Quebrada de La Sevilla, Dillon & Rodriguez 525* (F, TEX); Dillon & Rodriguez 533 (F, DILLON: SYSTEMATIC STUDY OF FLOURENSIA 59 5mm I cm FIG. 39. Flourensia leptopoda (from Dillon & Rodriguez 464, F). A, habit; B, capitulum; C, disc floret. TEX); Balcones, Sierra Ambato, Parodi 14067 (LP, us). Cordoba: Calamuchita, Valle de Los Reartes, Castellan- os 219 (si); Agua de Oro, Sierra Chica, Castellanos 3132 (LIL); Candonga, Dawson 1094 (GH, MO, LIL); west-facing slope of Cerro Pan de Azucar, Dillon & Luti 565* (F, MO, TEX, USM); near Yocsino, Dillon & Rodriguez 449* (F, MO, NY, TEX, USM); 4 km N of Capilla del Monte, Dillon & Rodriguez 450* (TEX), 451 (F, MO, TEX); Di- quecito, Hunziker 2747 (LIL, LP, si); La Falda, El Chor- rito, Job 440 (LP); Casabamba, Krapovickas 1903 (F, LIL); Sauce Punco, Tulumba, O'Donell 4536 (LIL, TEX, uc); Dean Funes, O 'Donell & Rodriguez 306 (LIL); Sierra Chi- ca, ca. 5 km W of La Calera, Solomon & Solomon 4059 (MO); La Estancia, Minas, Sola 1725 (LIL); Sierra Chica de Cordoba, Stuckert 4269 (LIL). Santiago del Estero: Cerro de Quazallan, Alberli 618 (LP); Ojo de Agua, Bir- aben 9 (LP), Vervoorst 613 (LIL). Flourensia campestris is distinguished from F. 60 FIELDIANA: BOTANY FIG. 40. Flourensia hirtissima (from Fischer 194, F). A, habit; B, capitulum. 2cm 1 cm B riparia, its nearest relative, by its small lanceolate to ovate leaves often with slight denticulations and smaller capitula with only 5-8 ray florets. It also shares relationships with F. leptopoda, and collec- tions from the southern Sierra Ambato have more pronounced leaf denticulations approaching those exhibited by the latter species. The population south of El Rodeo is exceptional in possessing re- duced size (ca. 50 cm tall) and strictly entire leaves with more truncate bases. Further study may show this population worthy of formal infraspecific rec- ognition. Flourensia campestris occupies a wide variety of habitats in the Sierra de Cordoba and is often subdominant in the more mesic sites. Flourensia oolepis and F. campestris occupy the same geo- graphical area in northwestern Cordoba, but each is ecologically isolated in this region. Flourensia campestris occurs in more mesic habitats at ele- vations below 1,000 m; F. oolepis, in contrast, occurs in drier sites usually above 1 ,000 m. I vis- ited populations of each species only 2-5 km apart near Capilla del Monte; however, they were never found growing sympatrically. These two species have strikingly different leaf shapes, capitules- cences, and number of ray florets. Neither field DILLON: SYSTEMATIC STUDY OF FLOURENSIA 61 FIG. 4 1 . Distribution of Flourensia hirtissima. observations nor herbarium material examined suggest any gene flow between these two species. Associates include Acacia, Larrea, Opuntia, and Prosopis. 30. Flourensia leptopoda S. F. Blake, Contr. U.S. Natl. Herb. 20: 406. 1921. TYPE: Argentina, La Rioja, Farrecillas, 5 March 1906, J. S. Ur- riche s. n. (holotype, B, destroyed; lectotype, here designated, fragment, GH!; photograph of B spec- imen, F!, GH!). Figures 30, 39. Shrubs to 1 m tall; stems erect to ascending, reddish brown. Leaves lanceolate to rhombic- ovate, 3-4.5 cm long, 1.3-2.5 cm wide, upper and lower surfaces strigillose to glabrous, basally cu- neate, apically acuminate, the margins deeply and irregularly repand-dentate, 4-6 pairs of cuspidate teeth; petioles 2-12 mm long. Capitulescences cy- mose, 2-4-headed; peduncles 1-4 cm long, brac- teate. Capitula radiate, ca. 8 mm high, 5-7 mm wide; involucres cylindric-campanulate; phylla- ries 2-seriate, equal, herbaceous, lanceolate to lance-subulate, 5-6 mm long, ca. 1 mm wide, api- cally attenuate; paleae oblanceolate, 6-8 mm long, apically attenuate; ray florets ca. 5, the ligules ob- long, ca. 7 mm long, ca. 4.5 mm wide, the tube ca. 4 mm long, glabrous; disc florets ca. 10, the corollas cylindric, ca. 5 mm long, the tube ca. 1 mm long, the lobes ca. 0.8 mm long. Achenes obconical, 5-8 mm long, the margins sericeous, the faces glabrescent; pappus of 2 awns, 3-4 mm long, persistent. Chromosome number: n = 18. FLOWERING (AND FRUITING) PERIOD— Febru- ary-March (March-April). DISTRIBUTION AND HABITAT (Fio. 30)— Known 62 FIELDIANA: BOTANY from sandy gravelly soils in arroyos of south-cen- tral La Rioja and adjacent San Juan, Argentina (1,500-1, 700m). SPECIMENS EXAMINED— ARGENTINA. La Rioja: Aguadita. Sierra de Olla, Castellanos 34021 (LIL); Iglesia, Frenguelli 508 (LIL); Sierra de Ulapes, Stuckert 17148 (LIL). San Juan: Valle de La Luna, near Ischigualasto, Dillon & Rodriguez 464* (BM, F, GH, HUT, MO, NY, TEX, USM); Quebrada de Gualcamayo, Chepical to El Salto, Roig 18965 (LP). Flourensia leptopoda is distinguished by pos- sessing rhombic-ovate to lanceolate leaves that are all deeply repand-dentate and capitula with 5 ray florets. Populations on the northern side of the Sierra del Valle Fertil in northeastern San Juan possess narrower leaves with larger denticulations. Its associates include Bulnesia, Halophytum, Echinocactus, Larrea, Opuntia, and Prosopis. 31. Flourensia hirtissima S. F. Blake, Contr. U.S. Natl. Herb. 22: 629. 1924. TYPE: Argentina, Rio Negro, General Roca and vicinity, on con- glomerate, 250-360 m, 31 Dec. 1914, W. Fisher 194 (holotype, us!; isotypes, BM!, F!, GH!, MO!, NY!, si!). Figures 40, 41. Subshrubs to 20 cm tall; stems erect; branchlets pilose-hirsute to glabrate, gray-brown. Leaves nar- rowly linear-lanceolate to linear-oblanceolate, 1 8- 48 mm long (including petioliform base), 2-4 mm wide, upper and lower surfaces densely hirsute, basally and apically attenuate, the margins entire, narrowly revolute. Capitulescences solitary, ter- minal; peduncles 4-7 cm long, densely pilose-hir- sute. Capitula radiate, 12-17 mm high, ca. 10 mm wide; involucres campanulate; phyllaries 2-seri- ate, subherbaceous, subequal, the outer phyllaries linear to lanceolate, 3-5 mm long, ca. 1 mm wide, apically acute, sparsely to densely hirsute, the in- ner lance-ovate, 6-9 mm long, ca. 2 mm wide, apically obtuse, densely hirsutulose-ciliate; paleae oblanceolate, 7-10 mm long, apically obtuse, densely hirsutulose; ray florets 5-8, the ligules ob- long-oval, ca. 10 mm long, ca. 5 mm wide, the tube ca. 5 mm long, hirsutulose; disc florets 10- 1 5, the corollas cylindric, ca. 6 mm long, the tube ca. 1.5 mm long, the lobes ca. 0.7 mm long, spi- culiferous. Achenes cuneate-oblong, ca. 6 mm long, densely sericeous; pappus of 2 awns, ca. 5 mm long, persistent. FLOWERING (AND FRUITING) PERIOD— Novem- ber-December (December). DISTRIBUTION AND HABITAT (Fio. 41)— This rare species is known only from the type locality and one additional collection from eastern Neuquen. Label data indicate that it occurs on limestone conglomerate on mesas and low hills. Cabrera (1971) cited the second-known collection (Perez- Moreau 3166, PAB) from Zapala, Neuquen; I have not examined this collection. Flourensia hirtissima is distinguished by its re- duced habit, hirsute leaves, and solitary capitula with densely hirsute phyllaries. Doubtful and Excluded Taxa Flourensia atacamensis (Philippi) Reiche, Ann. Univ. Chile 112: 146. 1903. Helianthus ata- camensis Philippi, Anal. Mus. Nac. Chile Bot. 1 89 1 : 48. 1 89 1 . TYPE: Chile, Antofagasta, Ata- cama, F. Philippi s.n. (holotype, B, destroyed; photograph of B specimen, F!). = Viguiera pa- zensis Rusby, Contr. Gray Herb. 54: 141. 1918. Flourensia corymbosa DC., Prodr. 5: 592. 1836. TYPE: Chile, Bio-bio, stoney fields near An- tuco, Jan. 1830. E. F. Poeppig 791 (holotype, G-DC, not seen, IDC Microfiche 800. 952: 1. 2!; isotype, F!). = Viguiera revoluta (Meyen) S. F. Blake, Contr. Gray Herb. 54: 121. 1918. Flourensia corymbosa var. araucana (Philippi) Reiche, Anal. Univ. Chile 1 12: 145. 1903. He- lianthus araucanus Philippi, Anal. Univ. Chile 90: 39. 1895. TYPE: Chile, s.d., F. Philippi s.n. (holotype, B, destroyed). Blake (1918) examined the type material at B and determined it to be Viguiera revoluta (Meyen) S. F. Blake, Contr. Gray Herb. 54: 121. 1918. Flourensia corymbosa var. lanceolata (Meyen) Reiche, Anal. Univ. Chile 112: 144. 1903. He- lianthus lanceolatus Meyen, Reise um die Erde 1:311. 1834. TYPE: Chile, s.d., F. J. F. Meyen s.n. (holotype, B, destroyed). Blake (1918) ex- amined the type material at B and determined it to be Viguiera revoluta (Meyen) S. F. Blake, Contr. Gray Herb. 54: 121. 1918. Flourensia gayana (Philippi) Reiche, Anal. Univ. Chile 112: 145. 1903. Helianthus gayanus Phi- lippi, Anal. Univ. Chile 90: 39. 1895. TYPE: Chile, s.d., F. Philippi s.n. (holotype, B, de- stroyed). Blake (1918) examined the type ma- terial at B and determined it to be Viguiera re- voluta (Meyen) S. F. Blake, Contr. Gray Herb. 54: 121. 1918. Flourensia hispida Philippi, Anal. Univ. Chile 36: 186. 1870. TYPE: Chile, s.d., R. A. Philippi s.n. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 63 (holotype, B, destroyed; lectotype, here desig- nated, w, not seen; photograph F!). = Viguiera gilliesii (Hook. & Arn.) Hieron., Contr. Gray Herb. 54: 119. 1918. Flourensia navarri (Philippi) Reiche, Anal. Univ. Chile 112: 145. 1903. Helianthus (Flourensia) navarri Philippi, Anal. Univ. Chile 90: 37. 1 895. TYPE: Chile, s.d., F. Philippi s.n. (holotype, B, destroyed). Blake (1921) examined the type ma- terial at B and determined this species to be a Wedelia. Flourensia polyclada S. F. Blake, Contr. U.S. Natl. Herb. 20: 403. 1921. TYPE: Argentina, La Rio- ja, entre La Cueva y La Encrucijada, Sierra Fa- matina, 29 Jan.-3 Feb. 1879, G. Hieronymus & G. Niederlein 541 (holotype, B, destroyed; iso- type fragment and photograph, F!, GH!). No ad- ditional type material has been located, and no collections examined in the present study match the description. It may be a synonym of Flour- ensia fiebrigii Blake; however, this would mark a considerable southward range extension for that species. Literature Cited AXELROD, D. I. 1970. Mesozoic paleogeography and early angiosperm history. Bot. Rev., 36: 277-319. BAILLON, H. E. 1886. Histoire des Plantes, vol. 8, p. 46. Hachette et Cie, Paris. BENTHAM, G. 1873. Notes on classification, history, and geographical distribution of Compositae. J. Linn. Soc., Bot., 13: 355-577. BLAKE, S. F. 1913. A revision of Encelia and some related genera. Proc. Amer. Acad. Arts, 49: 346-396. . 1916. Compositae novae imprinis andinae Weberbaueriana. Bot. Jahrb. Biebl., 54: 47-51. 1918. A revision of the genus Viguiera. Contr. Gray Herb., 54: 1-205. -. 1921. Revision of the genus Flourensia. Contr. U.S. Natl. Herb., 20: 393-409. . 1924. New American Asteraceae. Contr. U.S. Natl. Herb., 22: 587-661. 1935. New Asteraceae from the United States, Mexico, and South America. J. Wash. Acad. Sci., 25: 311-325. . 1950. Five new Asteraceae from Mexico and South America. J. Wash. Acad. Sci., 40: 47-50. CABRERA, A. 1971. Fitogeographia de la Republica Ar- gentina. Bol. Soc. Argent. Bot., 14: 1-42. CARLQUIST, S. 1981. Chance dispersal. Amer. Sci., 69: 509-516. . 1983. Intercontinental dispersal. In Kubitzki, K., ed., Dispersal and Distribution, pp. 37-47. Verlag Paul Parey, Hamburg, Germany. CRUDEN, R. W. 1966. Birds as agents of long-distance dispersal for disjunct plant groups of the temperate western hemisphere. Evolution, 20: 517-535. DECANDOLLE, A. P. 1836. Prodromus systematis na- turalis regni vegetabilis, part 5. Treuttel et Wurtz, Paris, 706 pp. Di FULVIO, T. E. 1977. Recuentos chromosomicos en Angiospermas Argentinas. HI. Kurtziana, 10: 69-72. DILLON, M. O. 1976. Two new species of Flourensia (Asteraceae-Heliantheae) from north-central Mexico. Southw. Naturalist, 21: 145-149. . 1979. Chromosome reports for Asteraceae. Taxon, 28: 278-279. . 1981. Three new species of Flourensia (Aster- aceae-Heliantheae) from South America. Ann. Mis- souri Bot. Gard., 68: 104-1 10. DILLON, M. O., AND T. J. MABRY. 1977. Flavonoid aglycones from Flourensia. Phytochemistry, 16: 1 3 1 8- 1319. DILLON, M. O., T. J. MABRY, E. BESSON, M. L. BOUIL- LANT, AND J. CHOPIN. 1976. New flavonoids from Flourensia cernua. Phytochemistry, 15: 1085-1086. ESTRADA, H., E. ESTRADA, AND L. MAYA. 1965. Estudio de la Flourensia resinosa. Bol. Inst. Quim. Univ. Nac. Auton. Mexico, 17: 68-75. GARDNER, J. L. 1951. Vegetation of the creosotebush area of Rio Grande Valley in New Mexico. Ecol. Monogr., 21: 379-403. GILLET, G. W., AND E. K. S. KIM. 1970. An experi- mental study of the genus Bidens (Asteraceae) in the Hawaiian Islands. Univ. Calif. Publ. Bot., 56: 1-63. GRAY, A. 1873. Notes on Compositae and characters of certain genera and species, etc. Part 1. Proc. Amer. Acad. Arts, 8: 631-661. . 1879. Characters of some new species of Com- positae in the Mexican collection made by C. C. Parry and Edward Palmer, chiefly in the Province of San Luis Potosi, in 1878. Proc. Amer. Acad. Arts, 15: 25- 52. . 1883. Contributions in North American bot- any. I. Characters of new Compositae, with revisions of certain genera and critical notes. Proc. Amer. Acad. Arts, 19: 1-73. HOFFMANN, O. 1890-94. Compositae. In Engler, A., and K. Prantl, Die Natiirlichen Pflanzenfamilien, vol. 4, part 5, pp. 87-387. W. Engelmann, Leipzig, Ger- many. HOLMGREN, P. K., W. KEUKEN, AND E. K. SCHOFIELD. 1981. Index Herbariorum. Part I. The Herbaria of the World, ed. 7. Oosthoek, Scheltema & Holkema, Utrecht, Netherlands, 452 pp. KINGSTON, D. G. I., M. M. RAO, AND T. D. SPITTLER. 1971. Isolation and structure determination of flour- ensic acid, a new sesquiterpene of the eremophilane type. Tetrahedron Lett., 20: 1613-1616. KINGSTON, D. G. I., M. M. RAO, T. D. SPITTLER, R. C. PETERSON, AND D. L. CULLEN. 1975. Sesquiterpenes from Flourensia cernua. Phytochemistry, 14: 2033- 2037. LEPPIK, E. E. 1970. Evolutionary differentiation of the flowering head of Compositae II. Ann. Bot. Fenn., 7: 325-352. 64 FIELDIANA: BOTANY MARTINEZ, M. 1969. Las Plantas Medicinales de Mex- ico, p. 186. Ediciones Botas, Mexico. MATHEWS, F. P. 1 944. The toxicity of the ripe fruit of blackbrush or tarbush (Flourensia cernua). Texas Agric. Exp. Sta. Bull., 664: 1-16. MAXWELL, R. A. 1968. The Big Bend of the Rio Grande. Univ. Texas, Bur. Econ. Geology Guidebook, 7: 1- 138. McVAUGH, R. 1956. Edward Palmer, Plant Explorer of the American West. University of Oklahoma Press, Norman, Oklahoma, 430 pp. MOLINA, G. I. 1782. Saggio sulla storia naturale del Chili, p. 160. Stamperia di S. Tomaso d' Aquino, Bo- logna, Italy. MOONEY, H. A., AND J. KuMMEROw. 1971. The com- parative water economy of representive evergreen sclerophyll and drought deciduous shrubs of Chile. Bot. Gaz. (Crawfordsville), 132: 245-252. MULLER, C. H. 1940. Plant succession in the Larrea- Flourensia climax. Ecology, 21: 206-212. RAO, M. M., D. G. I. KINGSTON, AND T. D. SPITTLER. 1970. Flavonoids from Flourensia cernua. Phyto- chemistry, 9: 227-228. RAVEN, P. H., AND D. AXELROD. 1975. Angiosperm biogeography and past continental movements. Ann. Missouri Bot. Gard, 61: 539-673. ROBINSON, H. 1981. A revision of the tribal and sub- tribal limits of the Heliantheae (Asteraceae). Smith- sonian Contr. Bot., 51: 1-102. RZEDOWSKJ, J. 1973. Geographical relationship of the flora of Mexican dry regions. In Graham, A., ed., Vegetation and Vegetational History of Northern Lat- in America, pp. 61-72. Elsevier Scientific Publishing Co., Amsterdam. SEAMAN, F. C. 1982. Sesquiterpene lactones as taxo- nomic characters in the Asteraceae. Bot. Rev., 48(2): 121-595. SEELIGMANN, P. 1960. Una nueva especie de Flour- ensia (Compositae). Lilloa, 30: 113-1 15. SIMPSON, B. B. 1975. Pleistocene changes in the flora of the high tropical Andes. Paleobiology, 1: 220-244. SOLBRIG, O. T. 1972. The floristic disjunctions between the "Monte" in Argentina and the "Sonoran Desert" in Mexico and the United States. Ann. Missouri Bot. Gard., 59:218-223. STROTHER, J. L. 1983. More chromosome numbers in Compositae. Amer. J. Bot., 70: 1217-1224. STUESSY, T. F. 1977. Heliantheae— systematic review. In Heywood, V. H., J. B. Harbome, and B. L. Turner, eds., Biology and Chemistry of the Compositae, pp. 621-671. Academic Press, London. TURNER, B. L. 1 972. Chemosystematic data: Their use in the study of disjunctions. Ann. Missouri Bot. Gard., 59: 152-164. . 1977. Summary of the biology of the Com- positae. In Heywood, V. H., J. B. Harborne, and B. L. Turner, eds., Biology and Chemistry of the Com- positae, pp. 1 105-1 1 18. Academic Press, London. TURNER, B. L., AND M. C. JOHNSTON. 1961. Chro- mosome numbers in the Compositae— III. Certain Mexican species. Brittonia, 13: 64-69. WILLIAMS, M. A. J. 1975. Late Pleistocene tropical aridity synchronous in both hemispheres? Nature, 253: 617-618. DILLON: SYSTEMATIC STUDY OF FLOURENSIA 65 Index of Latin and Common Names Names in Roman type refer to valid species; names in italics refer to synonyms. Numbers in boldface refer to descriptions; numbers in italics refer to illustrations. aserijaeba 38 Bidens 8 blackbrush 15 carcarillo 35 chilca 59 chilca gomosa 48 chilca negra 38 Diomedia 3 Diomedia thurifera 30 Encelia 3, 4, 5, 6 collodes 3, 22 glutinosa 3, 22 microphylla 3, 20 oblonga 3, 30 resinosa 3, 25 suffrutescens 3, 43 Enceliopsis 4, 5 engordadora 54 y/or