ve PHYTOLOGIA

An international journal to expedite botanical and phytoecological publication
Vol. 66 June 1989 No.5

CONTENTS

,GUY L. NESOM, Taxonomy of Erigeron sect. Polyactis (Compositae:

Astereae) SOSSSSSSSSSSSSSHSSSSSSHSSSSSSSHSSS SSS SSSSSSSSSSSSSHSSHSSSSSSSSHSSSSSSSSSSSSOSSSOSSOSSOO 41 5

B.L. TURNER, New species and combinations in Mexican Viguiera
(Asteraceae-Heliantheae) SSSSSSSSSSSHSSSSSSHSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSESSES 456

B.L. TURNER, New combinations in sect. Eremosis of Vernonia

(Asteraceae) SSHOSSHSSSSSHSSSSSSSSSSSSHSHSSSSOHSSSSSSSHSSSSOHOSSOSSHHSSSSSSOSSSSSSSOSSSSOSOO 462

LIBRA ARY

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Phytologia (June 1989) 66(5):415-455

TAXONOMY OF f8

ERON SECT. POLYACTIS
(COMPO E: AS

IG
A TEREAE )

Guy L. Nesom
Department of Botany, University of Texas, Austin 78713 U.S.A.

ABSTRACT

Erigeron sect. Polyactis (Less.) Nesom is prominently char-
acterized by arching-pendant buds, white ray corollas that sharply
reflex at maturity and a pappus of 10-12 caducous bristles that
break off cleanly at their very base. The bristles are completely
absent in five species and usually replaced by a short, hyaline
corona. The section is typified by FE. delphinifoltus Willd. and
comprises 19 species, most of which are endemic to the Sierra
Madre of western México. Nine new species are proposed here:
E. annuactis, E. basaseachensis, E. caulinifolius, E. cir-
culis, E. coroniglandifer, E. eruptens, E. nacoriensis, E.
podophyllus and E. rhizomactis. One new combination is
proposed: E. dactyloides (Greenm.) Nesom. The taxonomic
history of the name of the section is presented. Achaetogeron A.
Gray is included among the synonyms of Erigeron sect. Polyactis.

KEY WORDS: Erigeron, sect. Polyactis, Asteraceae, México,
systematics.

The present study treats a monophyletic group of 19 species, which are
formally described here as a section of Erigeron. Among these are taxa with
a typical pappus of bristles as well as several that have only a low, coroniform
pappus without bristles. The latter group includes Achaetogeron wishizent A.
Gray, the type of the genus Achaetogeron A. Gray.

STATUS OF THE GENUS ACHAETOGERON

Numerous Erigeron-like species with pappus bristles absent or reduced in
various ways have been placed into Achaetogeron since its original recognition
(Gray, 1849). Loss of pappus bristles in Erigeron, however, appears to have
occurred independently in at least six lineages, and more than once in at
least one of these (Nesom, unpublished). In addition to Erigeron wislizeni

415

416 PHY TOLOGIA volume 66(5):415-455 June 1989

(A. Gray) E. Greene, the following four species have pappus bristles absent
or reduced and have been treated as Achaetogeron: E. galeotti (A. Gray
ex Hemsl.) E. Greene, E. narcissus Nesom, E. gilensis Woot. & Standl.
and E. coronarius E. Greene. Each of these species represents a separate
lineage, each of which includes other epappose taxa. Further, EF. strigosus
Muhl. ex Willd. has ray achenes without bristles and could be considered to
represent another lineage in which loss of bristles has occurred. I could find
no features in plants of any of these lineages that would separate them from
typical Erigeron (Nesom, 1980).

E.L. Greene (1891) was the first to make formal transfers of Achaetogeron
species to Erigeron and a number of more contemporary botanists have com-
mented on the probable congeneric status of the two genera (e.g., Shinners,
1946; De Jong & Longpre, 1963; Pinkava & Keil, 1977). I published a
group of new names and new combinations that completed the transfer of
Achaetogeror, to Erigeron (Nesom, 1982). The present paper is the first to
treat a monophyletic group of Erigeron species that includes both pappose
and epappose taxa.

ERIGERON SECT. POLYACTIS - ITS NAME AND
CHARACTERISTICS

With several seasons of field experience in species-rich southern Chi-
huahua, I feel reasonably confident in presenting this treatment of a mono-
phyletic group of Erigeron species poorly or not at all represented in most
herbaria. Only three of the new species proposed here are described from sin-
gle collections of a taxon that I have not personally observed in the field. As
noted in the discussions below, however, a number of problems remain. Fur-
ther collecting and study in remote areas, particularly in northern Durango,
will be necessary to clarify the taxonomy of Erigeron sect. Polyactis.

Erigeron sect. Polyactis (Less.) Nesom, comb. et stat. nov. Based on
Polyactis Less., Syn. Comp. 188. 1832; non Link, 1809. Type species:
Erigeron delphinifolius Willd. Polyactidium DC, nom. nov., Prodr.
5:281. 1836.

Stenactis Cass., Dict. Sci. Nat. 37:485. 1825. Type species: Erigeron
delphinifolius Willd.; non sensu Less., 1832; non sensu Nees, 1832; non
Erigeron sect. Stenactis (Cass.) Torr. & Gray, Fl. N. Amer. 2(1):172.
1841.

Achaetogeron A. Gray, Mem. Amer. Acad. Arts, n. ser. 4(Pl. Fendl.):72.
1849. Type species: Achaetogeron wislizent A. Gray.

When Cassini first formally described the new genus Stenactis in 1825,
he cited three species as members, Erigeron (Aster) annuus (L.) Pers., E.
delphinifolius and E. alpinus L. and stated that the description was drawn

Nesom: Taxonomy of Erigeron sect. Polyactis 417

from the first two. One of the characters that he emphasized as important
in delimiting this group was the double pappus, but his description was
also specific about the caducous nature of the pappus. Of the three species
cited, only E. delphinifolius has a caducous pappus. The next year (Dict.
Sci. Nat. 39:404. 1826), he removed EF. annuus into a segregate genus,
Phalacroloma Cass. Still later, in redescribing Stenactis (Dict. Sci. Nat.
50:483. 1827), he specifically stated that the description was drawn from
E. delphinifolius, while including in the genus several more species with a
double but non-caducous pappus. The species cited in 1827 as composing
Stenactis primarily were the ones he had recognized in 1822 (Dict. Sci. Nat.
25:96) as sect. Diplopappus of the genus Diplopappus. However, in one of
the first circumscriptions of Diplopappus (Dict. Sci. Nat. 13:308. 1819),
Cassini formally cited four species, which are now recognized as Chrysopsis
(D. lanatus and D. intermedius), Aster, and Erigeron annuus (D. dubius).
Erigeron delphinifolius was mentioned in the 1819 discussion as a fifth species,
but was not given a name as Diplopappus until 1822. Since he later removed
both erigerons from this group, it is clear that the original reference of the
name Diplopappus was to Chrysopsis or Aster and that the first supraspecific
name for which EF. delphinifolius is typical is Stenactis Cass.

Torrey & Gray’s use of Stenactis at the sectional rank in Erigeron re-
ferred to six species that are not closely related to FE. delphinifolius and none
that were included among those cited by Cassini as belonging to Stenactis.
Erigeron annuus was moved by Torrey & Gray in the same publication to
sect. Phalacroloma and E. alpinus to sect. Erigeron, although E. delphini-
folius is a Mexican species and would not have been included in their floristic
treatment. Later, however, Gray pointed out (Proc. Amer. Acad. Arts 8:648.
1873) that sect. Stenactis Torr. & Gray was a synonym of sect. Phoenactts
Nutt. and that his own misapplication was based on the earlier misinter-
pretation of Stenactis by Nees & DeCandolle. In Gray’s Synoptical Flora
(1(2):219. 1884), he did not recognize Stenactis as a section, but he did cor-
rect his earlier concept of the name by noting Cassini’s original association of
Stenactis with E. delphinifolius and the close similarity of E. neomezicanus
with that species. Because, however, the type species of Stenactis Cass. was
excluded (see ICBN, Article 48.1) in the original publication by Torrey &
Gray, sect. Stenactis should be attributed solely to those authors and cited
as such, not as a new combination based on Cassini’s genus.

Lessing’s publication of the genus Polyaciis was superfluous (as well as a
later homonym), based on a misunderstanding of Cassini’s work, since Less-
ing retained the genus Stenactis with the sole species EF. annuus. DeCandolle
corrected Lessing’s creation of a later homonym, but Polyactidium, too, was
superfluous, a synonym of Stenactis. Nees, like Lessing, used Stenactis to
circumscribe a genus with EF. annuus and several other species but did not

418 PHY TOLOGIA volume 66(5):415-455 June 1989

include E. delphinifolius. Polyactis, however, appears to be the first name
typified by E. delphinifolius that is available for use at the rank of section.

Plants of sect. Polyactis are remarkably uniform in numerous aspects of
their morphology. Almost all of the species produce pinnatisect leaves and the
buds have a characteristic arching-pendant aspect that is easily recognized,
even at a distance. The ray flowers are narrow and reflex sharply at the
tube-ligule junction so that the corollas are held down around the involucre
(this is often apparent even on herbarium specimens). The style branch (disc
corolla) lengths and collecting appendage shapes are uniform. The pappus
bristles, when present, are mostly 10-12 in number and the bristles have
lateral constrictions at the very base, clearly perceptible with the SEM and
break off there with only slight pressure. The achenes of some species are
bristleless and usually have instead a hyaline corona or ring of partially fused
scales or setae.

The behavior of the phyllaries is linked to the condition of the pappus,
whether coroniform or of bristles. In those species with bristles, the phyl-
laries reflex or spread after maturation and release of the achenes; with an
evolutionary loss of the bristles, the phyllaries remain erect, even after the
achenes are dispersed. The reflexing behavior is more pronounced, however,
in species of Erigeron with persistent rather than caducous bristles.

I know of no other species of Erigeron with the peculiar arching-pendant
aspect of the buds nor of any with basally caducous pappus bristles. Reflexing
ray corollas, however, are found in various other parts of the genus and |
believe this feature is diagnostic in other species groups as well. In particular,
in plants of the E. coronarius E. Greene group (including E. pumilus Nutt.),
the ray corollas reflex and these species may be closely related to those of
sect. Polyactis (Nesom, in prep.).

In the morphological descriptions that follow, all measurements were
made from pressed specimens. Several types of trichomes, all multicellu-
lar, are found among the species treated here as well as the whole genus:
(Type A) uniseriate, usually comprising the most conspicuous vestiture, de-
scribed as hirsute, pilose, strigose, etc.; (Type B) uniseriate, very small and
usually inconspicuous, not found to be of diagnostic value at the species level
and not mentioned as such in the descriptions; (Type C) biseriate, glandu-
lar, described as “granular-glandular” in small size to “stipitate-glandular”

when larger and capitate. [lustrations of these trichomes are found in Nesom
(1976).

Erigeron sect. Polyactis
Leaves commonly pinnately coarsely toothed or lobed, less commonly en-

tire, the mid-region of the blade oblong and of even width. Heads shallowly
hemispheric to cupulate, markedly impressed below, buds arching-pendant;

Nesom: Taxonomy of Erigeron sect. Polyactis 419

phyllaries linear-lanceolate, with whitish but usually not scarious lateral
zones, in 3-4(-5) series of nearly equal length, but the inner often shorter
than the outer, reflexing to spreading after achene maturation and release in
the species with a pappus of bristles, remaining erect if pappus coroniform; re-
ceptacles flat to convex, smooth or alveolate. Ray flowers 50-230 in 2-4 series,
corollas 5-16 mm long, the ligules 0.6-1.2 mm wide, white and drying white
or sometimes cyanic in several species, sharply reflexing at the tube-ligule
junction at maturity. Disc corollas narrowly tubular-funnelform, 1.8-4.0 mm
long, the tube slightly constricted, barely or not at all inflated or indurated
above the constriction; style branches 0.4-0.7 mm long, including the deltate
to narrowly triangular collecting appendages 0.1-0.2 mm long. Achenes com-
pressed, mostly oblong-oblanceolate, (0.8-)1.0-1.3(-1.8) mm long; pappus of
mostly 10-12 (11-17 in E. podophyllus) brittle, basally caducous bristles, or
the bristles absent and replaced by an outer corona or series of scales, usually
basally fused, 0.1-0.2(-0.5) mm high. Chromosome number, n=9, 18 pairs.

All the species of Erigeron sect. Polyactis occur in the western Sierra
Madre of México. Thirteen species of sect. Polyactis are known only from
Chihuahua, Sonora and Durango. Two of them, E. neomezicanus and E.
oreophilus, range into the southwestern United States and the type species,
E. delphinifolius, has the major part of its range in the trans-volcanic moun-
tains of south-central México. Most occur above 1700 meters and are found
primarily in oak to oak-pine or pine woodlands but sometimes range into as-
sociated grasslands. Erigeron neomezicanus and FE. oreophilus occur as low
as 1100 meters.

The most significant differences among the species of sect. Polyactis are
in the type of pappus (coroniform or bristles) and the presence or absence of
rhizomes, stipitate-glandular trichomes and clasping leaves. Erigeron poly-
cephalus and E. annuactis have a distinctive leaf shape different from other
species. Comments on possible interspecific relationships follow individual
descriptions, but there is not sufficient basis for attempting to outline a hy-
pothesis of phylogeny for all the species.

I do believe, however, that the species of Erigeron sect. Polyactis with
a coroniform pappus (vs. pappus of bristles) comprise a distinct lineage.
This switch in pappus morphology apparently has entailed not only loss of
the bristles, but the elaboration of a corona, which is a structure probably
derived from the “outer” series of setae or scales. See the comments following
E. coroniglandifer for a caveat regarding this hypothesis.

SPECIES TAXONOMY
Artificial key to the species of sect. Polyactis

1. Achenes with a coroniform pappus, without bristles

). Achenes with a pappus of bristles. ..... s .w.nscoows «sonwo ewe aneneant- (6)

420 PHYTOLOGIA volume 66(5):415-455 June 1989

2. Cauline leaves clasping or subclasping ....................25. (3)

2. Cauline,Jeaves not at all clasping» ...i2isss,20. ade (4)

3. Plants producing slender, scale-leaved rhizomes; upper stem pubescence
appressed, eglandular® ©... 152202. ck. oot ee rae eee E. rhizomactis

3. Plants without rhizomes; upper stem pubescence spreading, usually
prominently stipitate-glandular ................... E. coroniglandifer

4. Basal leaves strongly bipinnatifid, produced at tips of slender rhi-
zomes; cauline leaves of erect stem ca 35; heads 6 mm wide; phyl-
lariés 2/5-3.0 mm long... hie es Wace. eee E. circulis

4. Basal leaves entire to toothed or lobed, never strongly bipinnatifid;
cauline leaves 10-30; heads 7-17 mm wide; phyllaries 3.1-5.5 mm
jong?’ ss 22%..8: Sec bes SO, Po ee ee eee (5)

. Phyllary margins thick, whitish; rays 115-180; pappus a corona 0.2-0.5
mm high, with an erose or scaly margin; receptacles alveolate FE. wis-
hzent

or

5. At least the inner phyllaries with relatively broad, hyaline margins;
tays 40-230; pappus a blunt, cartilaginous rim less than 0.05 mm high;
receptacles punctate to very shallowly alveolate ........... E. griseus

6. Plants annual

6. Plants perennial

7. Stems, leaves and phyllaries stipitate-glandular; leaves clasping to sub-
Clasping: fo0/5. 222 be. Lae a ee ee E. inoptatus

7. Plants eglandular or the phyllaries sometimes minutely granular-glandular;

leaves not, at all clasping. ...05...02-25.0% 20 vo, ac eee (8)
8. Cauline leaves pinnatifid to bipinnatifid ........ E. delphinifolius
8. Canline leaves entire .... 5s. acne ats ee E. annuactis

Ne}

. Cauline leaves clasping to subclasping

9. Cauline leaves not at all clasping

10. Stems eglandular, appressed-strigose at least near the heads;
cauline leaves obovate to oblong-obovate, the midregions
elliptic. SNe tee crc cree ae tect caso wereoe eee E. caulintfolius
10. Stems stipitate-glandular, hirsute-pilose; cauline leaves oblong-
oblanceolate to oblong-lanceolate, the midregions narrowly
oblong Se eee E. seemannit

11. Leaves serrate or crenate, the blades elliptic to elliptic- oblanceolate;
capitulescence-corymbose <x. / . 77) ses0scts coe oe ee E. polycephalus

Nesom: Taxonomy of Erigeron sect. Polyactis 421

11. Leaves pinnatifid, less commonly coarsely toothed, the blades mostly
oblong to oblong-lanceolate; heads solitary or in a loosely corymbose
CHEMUMCSEOUES | 5.66 soft van susie nc Ge aaa aoe is ae ee, (12)

12. Plants mostly 25-90 cm tall; stems usually with 2-20 primary
branches, these often with secondary and tertiary branches (13)

12. Plants mostly 10-30 cm tall; stems unbranched or with 1-2 simple
BIANChes Sc. Nye ret ge is So. bain ate e oe ae ea ar (15)

13. Stems, leaves and phyllaries moderately to densely appressed- strigose to
hirsute with trichomes averaging 0.4 mm long, eglandular or sometimes
minutely glandular on the phyllaries ............... E. neomezicanus

13. Stems, leaves and phyllaries sparsely hispid-pilose with trichomes av-
eraging 1.0 mm long, often the whole plant but at least the peduncles
and phyllaries densely stipitate-glandular ...................-.4. (14)

14. Leaves deeply pinnatifid with lobes evenly distributed along the
THORENS A025. or tee es ee te EL, See ee E. oreophilus

14. Leaves coarsely toothed or lobed only on the distal half, the blades
with a broad midregion of even width ........... E. dactyloides

15. At least the peduncles and upper leaves prominently stipitate-
ple tar o oo ade isis Sect el peicieslra. anal Sy share messes Pah cn eae E. oreophilus

15. Peduncles and upper leaves hairy, sometimes granular-glandular, but
never stipitate-glandular 4 ..co. (i. .<%aee kts 1 dodo. goss ae (16)

16. Inner and outer phyllaries with broad, scarious
FOBBPBRS 2 is ouochen Gian, oie. Haste eames Rae cae ee E. subacaulis

16. Inner phyllaries indurated to the edge or with a minute, hyaline

PBs GY olet Haaw sais. te bode waa eias =: apes Ae oerd ae ee (17)

17. Cauline leaves entire, apically toothed, or reduced to bracts on essen-
Pally Geapese SteMas Jerseys. o.0:8 csiniog ac! steno aie etme ee eee (18)

i +Caubine leaves: pirsniatiliel$. bjs) sies iste sors ccacge cin aackbemnetes: Sealed eee (20)

18. Plants with thick, lateral rhizomes; basal and lower cauline leaves
7-18 mm wide, 10-35 mm long, with 1-3(-4) pairs of coarse, apical
teeth or shallow lobes; pappus bristles 11-17 .... E. podophyllus

18. Plants with ascending caudex branches, not rhizomatous; basal
leaves pinnatifid; pappus bristles 10-12(-14) ............... (19)

19. Stems and phyllaries eglandular; cauline leaves 2-10 mm wide, 10-26
mm long, entire or shallowly toothed, reduced to bracts near the head;
heads 5-7 mm wide; disc corollas 2.4-3.0 mm long .... EF. nacoriensis

422 PHY TOLOGIA volume 66(5):415-455 June 1989

19. Stems and phyllaries glandular; cauline leaves absent or completely
bracteate (the stems scapose); heads 8-15 mm wide; disc corollas 3.5-
AUS WE OM see ices ooo 90: <n) lek des Norace esi eer ae ee E. eruptens

20. Plants mostly 10-30 cm tall, producing slender, brittle, lateral
rhizomes; basal rosette present at flowering; heads 6-9 mm wide;
ray Mowers’ 39-03°0s.50c258 6) oie eee E. basaseachensis

20. Plants mostly 25-90 cm tall, without rhizomes; basal rosette usu-
ally absent at flowering; heads 7-12 mm wide; ray flowers
TO=150s octk. ose Sege ee eee E. neomezicanus

Erigeron annuactis Nesom, sp. nov. Type: MEXICO, Michoacan: Mpio.
Uruapan, Cascadas de Tzararacua, [ca 10 km] S of Uruapan of Hwy
37, [19° 40’N, 102° 13’W], pine-oak woods, 1400 m, 16 Dec 1984, C.
Cowan 4866 (holotype: TEX!; isotype: MEXU [not seen]).

E. delphintfolio Willd. similis sed foliis penitus integris plerum-
que 3plo longioribus quam latioribus et corollis radii brevioribus
et paucioribus differt.

Annuals 6-7 dm tall. Stems with numerous branches on the upper 1/2-
1/3, sparsely short-strigose, eglandular, ridged-striate. Mid-cauline leaves
minutely strigose, elliptic-ovate to elliptic-obovate, 40-50 mm long, 13-16
mm wide, mostly 3 times longer than wide, epetiolate, entire, not even mu-
cronulate, not clasping, the upper cauline leaves narrowly elliptic to ovate or
lanceolate-ovate, 2.5-4.0 mm wide, 7-12 mm long. Heads 6-8 mm wide, on pe-
duncles 3-35 mm long; phyllaries 3.0-3.5 mm long, densely minutely granular-
glandular, without other vestiture or the outermost with a few small and very
inconspicuous hairs. Ray flowers 85-110 in 2-3 series, the corollas 5.5-6.2 mm
long, 0.8-1.0 mm wide. Disc corollas 3.0-3.3 mm long, indurated and slightly
inflated above the constriction. Achenes 0.8-0.9 mm long, sparsely strigose;
pappus of 8-10 bristles, without an outer series.

Known only from the type collection. Map 1.

Erigeron annuactis is represented by the top half of a single plant, but
Cowan’s label notes that it was an annual. It is obviously similar to E.
delphinifolius in duration and the structure of its capitulescence, but the
telatively broad, completely entire leaves are strikingly different from the
oinnatifid or bipinnatifid leaves of the latter. Further, in E. delphintfoltus
she upper cauline leaves are reduced to linear bracts (even these often deeply
obed) 0.5-1.2 mm wide, mostly 10-16 times longer than wide.

Erigeron annuactis is the only entire-leaved taxon in the section; the leaf
hape in this species is closest to that of E. polycephalus, although the latter
isually has toothed leaves and is strongly perennial. I believe these two, with
3. delphinifolius, which share corymbose capitulescences with relatively

Taxonomy of Erigeron sect. Polyactis 423

Nesom:

Sst[nvoreqns ‘q Ww

stzoenuue "FF VY

sntTojtutydtep ‘q @

1 dep

424 Pon ye Onl (OL Gri eA volume 66(5):415-455 June 1989

E. polycephalus

Map 2

Nesom: Vaxonomy of Erigeron sect. Polyoctes 125
~
a
a
A
4
a
aA,
%
atadag aa
A
aA aa

a

A
a

at

rN

a 4
ry
4 re
4
a 4a
a
a =
a E. neomexicanus
a

ee

426 PH YTOLOGIA volume 66(5):415-455 June 1989

short-peduncled heads, probably constitute a distinct lineage within the
section. It is not clear to which of these FE. annuactis may be most closely
related.

Erigeron annuactis occurs at the southern periphery of the range of both
E. delphinifolius and E. polycephalus and collections of both of the latter have
been made from the vicinity of Uruapan: E. delphinifolius, all with typically
deeply pinnatifid leaves (Tancitaro, Hinton 15556; 8 km S of Uruapan, King
& Soderstrom 4773; E. polycephalus (Uruapan, Woronow 2916).

Erigeron basaseachensis Nesom, sp. nov. Type: MEXICO, Chihuahua:
Mpio. Ocampo, ca 2.5 km S of village of Basasaeachic, area of La
Cascada de Basaseachic, 28° 02’N, 107° 55’W; area of pine-oak-juniper-
manzanita woodlands between parking area and top of falls; abundant
in crevices of steep, W-facing rock walls and shallow soil pockets in
boulders along river near falls, 18 Aug 1984, G. Nesom 5089 with P.
Lewis (holotype: TEX!; isotypes: ARIZ!,ASU!,CAS!,CIIDIR!,COLO!,
ENCB!,F!,GH!,MEXU!,NMC!,NY!,RM!,US!).

Ex speciebus sectionis Polyactis statura plerumque parva, rhi-
zomatibus tenuibus ligneis, vestimento eglanduloso, caulibus non-
tamosis ascendentibus ad basim, et capitulis solitariis in pedun-
culis longis distinguenda.

Herbaceous perennials from fibrous roots, producing short, slender, brittle
rhizomes. Stems basally ascending, (8-)10-30 cm tall, usually unbranched or
with 1-2 short, simple branches near the middle, sparsely pubescent with
antrorsely ascending to appressed hairs, eglandular. Leaves sparsely but
coarsely strigose, eglandular, the basal in a rosette, pinnatifid with 1-3 pairs
of obovate (to linear) lobes, 15-55(-75) mm long, 5-15 mm wide (lobe tip
to tip), petiole ca half the leaf length; the cauline reduced in size, non-
clasping, sessile, quickly becoming entire and oblanceolate. Heads solitary, 6-
9 mm wide, on naked peduncles 2.5-10.0 cm long; phyllaries sparsely strigose-
hirsute, eglandular, 3-4 mm long. Ray flowers 35-63 in a single series, the
corollas white, drying white to pinkish-purple, 7.0-9.0 mm long. Disc corollas
2.0-3.5 mm long. Achenes 0.9-1.2 mm long, sparsely strigose; pappus of (9-
)10-12 very slender, basally caducous bristles, with a prominent outer series
of very slender, lanceolate to oblong scales 0.1-0.3 mm high.

} Apparently endemic to the area of the confluence of Rio Candameia and
Rio Durazno south of Basaseachic in southwestern Chihuahua; on the plateau
primarily in areas of pine and pine-oak woods, N and W-facing cliff crevices
and shallow soil pockets in boulders alongside the river, rarely in sandy soil
of floodplain (2050-2100 m), and on wet rocks and cliffs at base of the falls
(ca 1800 m); flowering August-October. Map 5.

Additional collections examined: MEXICO, Chihuahua: [Type locality]:
banks of small stream entering Rio Candamena, near wooden footbridge on

Nesoin: laxonomy of Erigeron sect. Polyac Is 42

Aa a
a
aA
a
4a
a
4
a a
4 GN
a
' A x
“ a
a
a
as a
a

Be ©reophilus

Y

(see citation)

428 PHY TOLOGIA volume 66(5):415-455 June 1989

trail to falls, 17-20 Oct 1986, Nesom 5536 (TEX,MEXU); beside Rio
Durazno, 17-20 Oct 1986, Nesom 5609 (MEXU,NMC,TEX); base of falls,
14 Oct 1984, Spellenberg 7935 (NMC,TEX); plateau above falls, 14 Oct
1984, Spellenberg 7912 (TEX).

The plants of the type collection are similar to those collected by Spellen-
berg. Those of Nesom 5536 have slightly longer stems (to 40 cm long) and
the cauline leaves are unreduced or slightly enlarged from the basal. How-
ever, the stems appear to have regrown from a point below where the original
ones had been broken off. They are otherwise identical to the typical plants
and are probably aberrant growth forms.

Erigeron basaseachensis is distinguished from all the species of sect. Poly-
actis by its combination of small size, slender, woody rhizomes, sparsely
strigose, eglandular vestiture, mostly unbranched, basally ascending stems
and solitary heads on long peduncles. In the area of Basaseachic, it is sim-
ilar to E. neomezicanus which differs in its larger stature, lack of rhizomes,
spreading stem pubescence (in the Basaseachic area) of much coarser hairs,
basal leaves usually absent by flowering, loosely corymbose capitulescence
borne on stems branched in the upper third and fewer ray flowers on mostly
smaller heads.

Erigeron caulinifolius Nesom, sp. nov. Type: MEXICO, Chihuahua:
Mpio. Guadalupe y Calvo, NW side of Cerro Mohinora, ca 12.5 mi SW
of Guadalupe y Calvo, past turnoff to peak, downslope on road toward
Sinaloa; 25° 57’N, 107° 03’W; abundant on cliff faces, in area of oak-
pine-fir and scattered madronos, 2470 m, 20 Aug 1988, G. Nesom 6483a
with A. McDonald (holotype: TEX!; isotypes: ARIZ!,CIIDIR!,COLO!,
GH!,MEXU!,MICH!,MO!,NMC!,NY!,RM!,US).

Ex affinitate sect. Polyactis distinguenda caulibus pubescentia
supera appressa infera patenti, foliis caulium amplis obovatis vel
oblongi-obovatis grosse serratis prope apices amplectentibus non-
ampliatis ad bases, capitulescentiis laxe corymbosis, capitulis in
pedunculis brevibus, et pappo setis.

Perennial herbs from a short caudex, producing numerous fibrous roots,
sometimes with a short (2-5 cm), thickened rhizome. Stems 30-55 cm tall,
with 4-8(-12) branches on the upper half, often with secondary branches,
pubescence sparsely spreading to spreading-deflexed pubescence on the lower
2/3-3/4, appressed-strigose near the heads, eglandular. Leaves sparsely to
moderately strigose, eglandular, the basal ovate-elliptic, 5-15 cm long, serrate-
dentate to somewhat lyrate with 5-10 pairs of coarse teeth or basal lobes,
basally attenuate to a petiole 1/3-1/2 the leaf length; cauline leaves obovate
to oblong-obovate, often widely so, oblong-lanceolate in the capitulescence,

a ly of Brigeron sect. Polyactis 42y
Nesom: axOnomly rig

O E. basaseachensis
A E. podophyllus

O E. caulinifolius
@ E. eruptens

AE. nacoriensis

e

o®@

a a)
8

430 PHY TOLOGIA volume 66(5):415-455 June 1989

the middle 32-85 mm long, 9-25 mm wide, coarsely serrate to
dentate-serrate on the distal 1/2-2/3, clasping to subclasping but not
basally ampliate. Heads in a loosely corymbose capitulescence, 11-13 mm
wide, on peduncles 15-35 mm long; phyllaries 4.5-6.0 mm long, sparsely
strigose-hispid, sparsely stipitate-glandular. Ray flowers 125-180 in 2-3
series, the corollas white, 11-16 mm long. Disc corollas 3.0-3.5 mm long.
Achenes with 2(-3) orange nerves, sparsely strigose, mature size not
observed; pappus of 10-12 slender, brittle and basally caducous bristles
slightly shorter than the disc corollas, with an outer series of minute,
slightly basally fused scales 0.1 mm high.

Known only from the area of Cerro Mohinora in southern Chihuahua;
steep, rocky faces and roadbanks, area of pine-oak-fir; 2450-3100 m; Aug-
[Oct]. Map 5.

Additional collections examined: MEXICO, Chihuahua: Mpio. Guadalupe
y Calvo, Cerro Mohinora, bosque conifero, 3100 m, 27 Aug 1987, McDonald
2412 (TEX); NE side of Cerro Mohinora, ca 2 mi below summit, ca 11 mi
SW of Guadalupe y Calvo, steep, rocky roadbank in pine-fir-aspen woods,
2610 m, 21 Aug 1988, Nesom 6481 with McDonald (MEXU,TEX).

Erigeron caulinifolius is distinct among all the species of sect. Polyactis
in its very large, coarsely toothed, obovate to oblong-obovate, and clasping
but not basally ampliate cauline leaves. Other distinguishing features of
this species are the following: stem pubescence spreading to deflexed on the
lower 3/4, appressed-strigose above, otherwise eglandular, heads on short
peduncles in a loosely corymbose capitulescence and pappus of bristles. It is
similar to and perhaps most closely related to E. seemannii but the latter has
stem pubescence spreading from bottom to top, leaves with narrowly oblong
midregions and densely stipitate-glandular stems, leaves and phyllaries.

Erigeron circulis Nesom, sp. nov. Type: MEXICO, Chihuahua: La
Rocha, along tributary of Rio del Soldado, on N-facing conifer slope,
Sierra Mohinora, [ca 26° 07’N, 107° 03’W], 7500 ft, 14-15 Oct 1959,
D.S. Correll & H.S. Gentry 23122 (holotype: LL!).

E. delphinifolio Willd. similis pubescentia caulium appressa,
foliis basalibus bipinnatisectis, et foliis caulium non-amplectentibus
sed rhizomatibus brevibus, foliis caulium integris, capitulis soli-
tariis minoribus, flosculis minoribus, et pappo sine setis differt.

Perennial herbs from fibrous roots, producing slender rhizomes, ascend-
ing at the tips and producing a rosette of leaves. Erect stem 31 cm tall,
moderately strigose with closely appressed to ascending hairs, eglandular.
Leaves sparsely strigose, eglandular, the basal 3-4 cm long, the blades widely
obovate in outline, 12-19 mm wide, bipinnatifid with 3-4 pairs of primary
oblanceolate lobes, the sinuses extending 9/10 of the distance to the midrib,
secondary lobes much shallower, the cauline 35 in number, 20-40 mm long,

Nesom: Taxonomy of Lrigeron sect. Volyactis 431

ry a

=

A A E. dactyloides
A Ts
A O E. inoptatus
4 E. coroniglandifer
@ E. seemannii
e)
0 O oO O
o O
re) Oo
Oo

432 PHY TOLOGIA volume 66(5):415-455 June 1989

3-5 mm wide, narrowly oblong to lanceolate, epetiolate, not clasping, entire
or with 1-2 shallow teeth near the apex, unreduced in size until the
peduncle, the uppermost reduced to linear bracts. Head 6 mm wide,
solitary on a peduncle 7 cm long; phyllaries in 2-3 subequal series, the inner
3.0 mm long, the outermost 2/3 as long, very sparsely strigose, eglandular,
Ray flowers ca 70 in 2-3 series, the corollas white, 7-11 mm long. Disc
corollas 1.9-2.7 mm long. Achenes with 2 (thin?) ribs, sparsely strigose,
mature size not observed; pappus a ring of irregular scales or a fimbriolate
corona less than 0.1 mm high.

Known only from the type collection. Map 7. The site at La Rocha was on
the northeastern slope of Cerro Mohinora (Correll, 1959). Correll noted that
the collecting site was along the tributary of Rio del Soldado in a gorge facing
southwest with “flumes and miniature fall” cut by the stream and “sheltered
by a dense forest of balsam and pine. Sheltered in this fern paradise were
found 23 species of ferns, 6 of which were new to the known flora of Chi-
huahua.” Correll described his experience there as “one of the thrills of a
lifetime.”

Erigeron circulis is characterized by slender rhizomes, appressed stem
pubescence, very small, deeply dissected, bipinnatifid basal leaves, mostly
entire, non-clasping cauline leaves, small solitary heads with small flowers
and achenes lacking a pappus of bristles. The coroniform pappus clearly
places it as a member of the E. wislizent group, but the only other plants
in the section with such highly dissected leaves are forms from Durango of
E. delphinifolius, with which it is compared in the diagnosis. In the area of
Cerro Mohinora, E. rhizomactis also has slender rhizomes and a coroniform
pappus, but it has many different features, including mostly entire to few-
toothed basal leaves, clasping cauline leaves and much larger heads with
longer and more numerous ray flowers and longer disc corollas. Plants of £.
wislizeni have neither such dimorphic leaves (basal vs. cauline) nor slender
rhizomes.

The plant of Erigeron circulis is mounted on a sheet with three plants
of E. strigulosus E. Greene. The latter is in a different section of the genus
and prominently different from E. circulis in many ways, including its lack
of rhizomes, spreading stem pubescence, entire leaves, clasping cauline leaves
and more numerous ray flowers with coiling ligules.

Erigeron coroniglandifer Nesom, sp. nov. Type: MEXICO, Chihuahua:
Mpio. Guadalupe y Calvo, 1.3 km S of bridge in Turuachi near base of
steep canyon, 78.9 km SW of El Vergél, 26° 09’N, 106° 44’W; area of
pine-oak and madrono, 2050 m, plants abundant in shallow soil over
steep, rocky slope, 28 Aug 1983, G. Nesom 4964 (holotype: TEX!; iso-
types: ARIZ!,ASU!,CAS! CHAPA!,CIIDIR!,COLO!,ENCB!,F!, GH!,K!,
M!,MEXU!,MO!,NMC!,NY!,RM!,US).

Nesom: Taxonomy of Erigeron sect. Polyactis 433

we

4 E. wislizeni

circulis

rhizomactis

griseus

434 PHY TOLOGIA volume 66(5):415-455 June 1989

E. seemannii (Schultz-Bip. ex Seem.) E. Greene similis sed
pappo hyalino coroniformi sine setis differt.

Perennial herbs, producing fibrous roots from a very short, thick rhizome.
Stems 25-46 cm tall, simple or with 2-5 branches from near the middle or
somewhat above, sparsely to densely hispid-pilose from bottom to top, some-
times slightly deflexed, densely and prominently stipitate-glandular or some-
times the glands smaller and relatively inconspicuous. Basal leaves pinnately
lobed or toothed, usually deciduous by flowering, the lower cauline narrowly
oblong to oblanceolate, coarsely toothed to shallowly lobed on the distal half,
with a broad midregion of even width, becoming lanceolate and entire or
nearly so upwards, the largest 47 cm long, 5-18 mm wide, 410 times longer
than wide, little reduced in size until the peduncles, mostly sessile with clasp-
ing to subclasping, slightly ampliate bases, stipitate-glandular and sparsely
hispid. Heads 9-15 mm wide, on naked peduncles 7-15 cm long; phyllaries
very sparsely to densely hispid-pilose, prominently stipitate-glandular. Ray
flowers 115-225 in 2-3 series, corollas white, sometimes drying with a lilac
tinge, 7.0-8.5 mm long. Disc corollas 2.2-3.0 mm long. Achenes 1.0-1.3 mm
long, with 2, thickish, white ribs, glabrous to very sparsely strigose; pappus
a thin, hyaline, erose-margined corona 0.05-0.1 mm high.

Northern Durango and southern Chihuahua; rocky habitats in areas of
pine-oak woods; 2050-2700 m; Jul-Sep. Map 6.

Additional collections examined: MEXICO, Chihuahua: Mpio. Guadalupe
y Calvo, 16 km S of bridge in Turuachi near top of road upgrade through
canyon from Turuachi, ndge overlooking town of Yerbitas, 0.5 km S of
Guadalupe y Calvo-Atascaderos jct, 2600 m, abundant on dry, rocky slope,
26 Aug 1983, Nesom 4978 (TEX); ca 13 mi E of Guadalupe y Calvo, 4.5 mi
W of jct to Atascaderos, clearing in pine-oak woods, 2700 m, 24 Aug 1984,
Nesom 51476 (TEX). Durango: Mpio. Santiago Papasquiaro, ca 22 air mi
WNW of Santiago Papasquiaro, 3.3 mi by Topia Rd W of the sierra crest
from jct with road to antenna, crest of mountain with pine and oak, ca 8750
ft, 25 Aug 1983, Corral & Worthington 11445.5 (TEX); [Mpio. Canelos],
[ca 35 km SE of Topia], ca 100 mi NW of Santiago Papasquiaro, 11 mi E
of Cienega Nuestra Senora, 19 Sep 1982, Spellenberg & Zimmerman 6764
(NMC,TEX); Mpio. Tepehuanes, “Buenos Aires,” 36 km W of Tepehuanes,
[por la brecha a] Topia, pine-oak woods, 22 Jul 1982, Tenorio L. 1187 (TEX).

Erigeron coroniglandifer is very similar to E. seemannti in its perennial
habit, stipitate-glandular stems, leaves and phyllaries, its long, naked pedun-
cles, completely spreading stem pubescence and clasping leaves with broad
midregions. The latter, however, has a pappus of caducous bristles with no
outer series. Erigeron coroniglandifer completely lacks bristles but has a hya-
line corona. It apparently is restricted to the high mountains and plateaus of
northwestern Durango and extreme southern Chihuahua; no populations of

Nesom: Taxonomy of Erigeron sect. Polyactis 435

E. seemannii have been found in that area. Erigeron seemannii has a wider
distribution from south-central Durango to southern Chihuahua. Although
the morphological difference between the two taxa is small, it is striking and
accompanied by geographic differentiation. The close similarity between the
two species suggests that FE. coroniglandifer may be derived directly from
E. seemannit, in which case the former would be a high-elevation isolate,
probably similar in origin to that of E. rhizomactis from E. wislizeni. If
the difference between a coroniform pappus and one of bristles, however, is
more basic (see comments in Introduction), E. coroniglandtfer may be closely
telated to the EF. wislizent group.

Erigeron dactyloides (Greenm.) Nesom, comb. nov. Based on Erigeron
oreophilus var. dactyloides Greenm., Proc. Amer. Acad. Arts 41:258.
1905. Type: MEXICO, Chihuahua: [Mpio. Casas Grandes], near Colo-
ma Garcia in the Sierra Madre, 1-20 Aug 1899, E.W. Nelson 6220
(lectotype designated here: GH!; isolectotype: US!).

Perennials, with stems, leaves, peduncles and phyllaries stipitate-glandular,
the glands larger and denser on the upper part of the plants. Stems erect, ca
0.6-1.0 m tall, glandular and sparsely hispid-pilose, Leaves (mid-cauline) not
clasping, 5-8 cm long, oblong to oblong-oblanceolate, 8-12 mm wide, narrow-
ing slightly near the tip, of nearly uniform breadth in the proximal 1/2-2/3,
with 1-2(-7) pairs of shallow lanceolate lobes on the distal margins, often
with 3, prominent longitudinal veins, entire, more lanceolate and somewhat
reduced in size on the upper portions of the stem. Heads 8-10 mm wide,
in a leafy capitulescence; phyllaries densely stipitate-glandular but with few
other hairs. Ray flowers 140-160. Disc corollas 2.7-3.0 mm long. Mature
achenes not seen; pappus of 10-12 bristles, with a distinct, outer series of
triangular-lanceolate scales 0.1 mm high.

Northwestern Chihuahua and adjacent Sonora; rocky sites in oak-pine
woods; 2250-3000 m; Aug-Oct. Map 6.

Additional collections examined: MEXICO, Chihuahua: E side of San
Luis Mts, 11 Sep 1893, Mearns 2232 (CAS); Strawberry Creek, NE of Colo-
nia Pacheco, 22-24 Sep 1934, Pennell 19172 (US); cool slopes, foothills of
the Sierra Madre, 11 Oct 1887, Pringle 1272 (GH,MEXU,MICH,PH,US);
near Colonia Garcia in the Sierra Madre, 4 Sep 1899, Townsend & Bar-
ber 305 (GH,MEXU,MICH,MO,NMC,UC,US), 306 (MEXU); ca 25 mi W
of Colonia Juaréz on road to Colonia Pacheco, 20 Sep 1981, Warnock 2334
(TEX). Sonora: Cafion Internacional, oak-pine zone, 23 Aug 1940, White
3507 (MEXU,MICH).

I earlier maintained this taxon as a variant of E. oreophilus (Nesom, 1980)
but now consider it to be distinct at the rank of species. Erigeron dactyloides
has larger, oblong leaves with 1-3 teeth or small lobes on the upper 1/2-2/3
of the blade and a broad midregion of even width, commonly with three

436 PHY TOLOGIA volume 66(5):415-455 June 1989

longitudinal veins. In contrast, over its whole geographic range, the leaves
of E. oreophilus are generally smaller and consistently deeply pinnatifid with
lobes evenly spaced along the margins. Additionally, EF. dactyloides appears
to be restricted to a relatively small area in northwestern Chihuahua and
adjacent Sonora.

The “dactyloides” leaf form is also found in Erigeron seemannit, E. in-
optatus and E. coroniglandifer and I believe E. dactyloides is most closely
related to E. seemanni rather than £E. oreophilus All three species have
a densely stipitate-glandular vestiture. Erigeron seemannii differs from E.
dactyloides in its cauline leaves with clasping to subclasping, ampliate bases
and its pappus without an outer series of scales. See further comments fol-
lowing E. seemannit.

Erigeron dactyloides and E. oreophilus have been collected in close. prox-
imity. Two of the collections cited above were of mixed species: Townsend
& Barber 306 (CAS) and Mearns 2232 (DS) are typical E. oreophilus.

Erigeron delphintfolius Willd., Enum. Hort. Berol. 2:873. 1809. Type: In
America meridionali, Humboldt & Bonpland s.n. (holotype: B [not
seen], drawing by Klatt in GH!). Diplopappus delphinifolius (Willd.)
Cass., Dict. Sci. Nat. 25:96. 1822. Polyactis delphinifolius (Willd.)
Cass., Dict. Sci. Nat. 37:485. 1825; 50:483. 1827. Polyactis del-
phinifolius (Willd.) Less., Syn. Comp. 189. 1832. Polyactidium del-
phintfolium (Willd.) DC., Prodr. 5:282. 1836. Erigeron delphinifohus
subsp. delphintfolius Cronq., Brittonia 6:263. 1947.

Achaetogeron fisheri Larsen, J. Washington Acad. Sci. 38:200. 1948. Type:
MEXICO, México: Amecameca, 9000 ft, 29 Jul 1924, G.L. Fisher s.n.
(holotype: MO!; isotype: ARIZ!).

Achaetogeron sophitfolius Larsen, J. Washington Acad. Sci. 38:200. 1948.
Type: MEXICO, Durango: City of Durango and vicinity, Apr-Nov
1896, E. Palmer 158 (holotype: MO!; isotypes: MEXU!,NY!,UC-2
sheets!,US!).

Annual herbs from a woody but slender taproot. Stems 1(-5) from the
base, 20-70(-170) cm tall, with (1-)4-10 primary branches on the upper 1/2-
2/3, these usually branched also, antrorsely appressed-strigose on the upper
1/4-3/4, spreading to retrorse below that, appressed from bottom to top, es-
sentially eglandular. Leaves strigose, sometimes minutely granular-glandular;
basal leaves obovate, coarsely serrate or crenate to pinnately lobed, attenuate
to a petiole 1/2-2/3 as long as the leaf; cauline leaves pinnatifid to bipinnat-
ifid with 2-5 pairs of narrowly lanceolate to oblanceolate lobes, 15-90 mm
long, 350 mm wide, not clasping, the lower petiolate, sessile and reduced
in size upwards. Heads 7-14 mm wide, (2-)6-35 in a loose, corymbose ca-
pitulescence, on relatively naked peduncles mostly 1-7 cm long; phyllaries

Nesom: Taxonomy of Erigeron sect. Polyactis 437

3.1-6.2 mm long, minutely granular-glandular. Ray flowers 110-240(-325) in
23 series, corollas white, 8.0-14.9 mm long. Disc corollas 2.2-3.1 mm long.
Achenes 0.9-1.6 mm long, with 2, thick ribs; pappus of 6-10(-12) caducous
bristles nearly as high as the disc corolla, with an outer corona or series of
scales 0.1-0.2 mm high or sometimes lacking. Chromosome number, n=9, 18
pairs.

Western sierra in Durango, Nayarit, Zacatecas, Jalisco and Aguascalientes,
eastward (primarily in the trans-volcanic range) through Michoacan, Guana-
juato, San Luis Potosi, Querétaro, Hidalgo, México, Morelos, Tlaxcala and
Puebla; common in a variety of open vegetation or disturbed sites, common
along roadsides; mostly 1700-2750 m; Jul-Nov and sporadically throughout
the year at lower elevations. Map 1.

Representative collections examined: MEXICO, Aguascalientes: ca 20 km
E of Rincon de Romos, 48 Sep 1967, McVaugh 23732 (DS,MICH). Distrito
Federal: Santa Fe, 17 Aug 1865, Bourgeau 717 (GH). Durango: City of Du-
rango and vicinity, Nov 1896, Palmer 928 (GH,MEXU,MO,NY,UC,US); San-
dia Station, 16 Oct 1905, Pringle 13548 (CAS,GH,LL,MICH,US). Guanaju-
ato: Ravin de Esperanza, Aug 1895, Duges s.n. (GH). Hidalgo: Buena Vista,
near Sierra de Pachuca, 4 Aug 1904, Pringle 13452 (GH,MICH,US). Jalisco:
Rio Blanco, Jul 1886, Palmer 166 (GH,MICH,NY,PH,US). México: Flor de
Maria, 21 Aug 1890, Pringle 3235 (GH,MICH,MO,MU,MEXU,NY,PH,UC,
US). Michoacan: Tancitaro, 22 Oct 1940, Hinton 15556 (LL,MICH,NY,UC,
US); ca 8 km S of Uruapan, 11-15 Oct 1961, King & Soderstrom 4773
(MEXU,MICH,NY,SMU,TEX,UC,US). Morelos: México to Cuernavaca toll
toad, 6 Jan 1957, Langman 4119 (PH). Nayarit: Arroyo Santa Rosa, W of
Santa Teresa, 100 air km NNE of Tepic, 21-24 Oct 1979, Breedlove 44542
(CAS). Puebla: between Acatzingo and El Seco, 10 Oct 1944, Sharp 441262
(GH, MEXU,NY,TENN). Querétaro: 1.5 mi W of El Ciervo, 30 Aug 1965,
Flyr 601 (SMU). San Luis Potosi: Region of San Luis Potosi, 1878, Parry
& Palmer 389 (DS,MO,NY,PH, US). Tlaxcala: ca 3 mi N of Zacatelco on
Hwy 119, 24 Jan 1960, King 2254 (MICH,TEX). Zacatecas: 13 mi ESE of
Sombrerete on Hwy 45, 5 Aug 1977, Nesom 610 (NCU).

Erigeron delphinifolius has been considered conspecific with E. neomezt-
cantus (Cronquist, 1947), but the latter is a perennial from a strongly woody
base. Further, the two taxa are allopatric with distinct geographic ranges
and occur in very different types of habitats.

In Durango the cauline leaves of Erigeron delphinifolius have a stronger
tendency to be pinnatifid, the upper leaves are often more densely glandular
and the appressed pubescence is more restricted to the upper portions of the
stems than in plants to the southeast. The type of Achaetogeron sophifolius
has tripinnatifid leaves, but this apparently represents only an extreme of
the tendency for greater lobing in Durango.

438 PH YTOLOGIA volume 66(5):415-455 June 1989

One collection from northeastern Durango (Pringle 13548) has an ex-
ceptionally high number of ray flowers (ca 350-400), extremely large and
persistent basal leaves and only 2-4 pappus bristles per achene.

Erigeron delphintfolius is the only annual besides E. inoptatus and E.
annuactis in sect. Polyactis, the only species with strong colonizing tendencies
and the only species that ranges outside of the western Sierra Madre. The
center of morphological variability for the species is in the westernmost part
of its range, near the center of species diversity for the section and it is almost
certain that the wide distribution of E. delphintfolius across the trans-volcanic
mountains was attained after its evolutionary origin in the western sierra.

Erigeron eruptens Nesom, sp. nov. Type: MEXICO, Chihuahua: Mpio.
Ocampo, 18 mi SE of jct of Tomochic-Yepachic road on road to San
Juanito, 2 mi SE of Yoquiva (ca 24 mi SE of Basaseachic), [ca 28° 07’N,
108° 02’W], on ca 45° NW-facing, open slope, ca 7500 ft, 27 Apr 1984,
Spellenberg et al. 8070 (holotype: TEX!; isotypes: ARIZ,ASU,COLO!,
ENCB,INIF,K,MEXU,NMC,NY,RSA,UC,UNM,US,UTEP).

Ex speciebus sectionis Polyactis habitu dense cespitoso, ramis
caudicis ascendentibus, et caulibus strictis quasi scaposis, minute
stipitati-glandulosis distinguenda.

Herbaceous perennials from a taproot or fibrous roots, usually densely
cespitose (forming clumps up to 4 dm in diameter) from several, ascending
caudex branches, each branch producing an obconic rosette of erect basal
leaves and 1-numerous, erect, merely bracteate stems. Stems 7-32 cm tall,
unbranched or rarely with a branch on the upper half, minutely but promi-
nently stipitate-glandular, very sparsely hispid-pilose, the hairs sometimes
slightly deflexed, ascending appressed in S Chihuahua. Basal leaves obovate
in outline, pinnatifid with (1-)2-4 pairs of obovate lobes, these sometimes
coarsely toothed, mostly 10-30 mm wide (lobe tip to tip) (-45 in S Chi), 2-12
cm long with a petiolar region ca half as long as the leaf, sparsely to densely
strigose-hispid with arching hairs, eglandular or essentially so; cauline leaves
all reduced to linear-lanceolate, non-clasping bracts. Heads solitary on essen-
tially scapose stems, 8-15 mm wide; phyllaries 3.8-5.0 mm long, densely and
minutely stipitate-glandular, otherwise sparsely pilose. Ray flowers 26-72 in
1 series, corollas white, drying white to light lavender, 8-11 mm long. Disc
corollas 3.5-4.5 mm long. Achenes oblong, ca 1.0 mm (1.9 mm in S Chi) long,
with 2(-3) thin ribs; pappus of 10-12 basally caducous bristles, with an outer
series of setae and linear scales 0.1-0.2 mm high.

Southwestern to southern Chihuahua; open banks, usually steep and of
loose and bare soil, or crevices or ledges of cliffs, in areas of pine or pine-oak

forest, commonly with fir; 2150-2400 m; flowering April-June(-August). Map
5.

Nesom: Taxonomy of Erigeron sect. Polyactis 439

Additional collections examined: MEXICO, Chihuahua: Mpio. Bocoyna:
ca 15 air mi SW of San Juanito, 6.5 mi SE of jct of road to Maguarichi
from San Juanito-Basaseachic road, 1 mi NW of Talayotes, in mesic, cool
canyon bottom, area called “Arroyo del Gato” on banks, 28 Apr 1985 Spel-
lenberg et al. 8114 (TEX - dups not seen at ID.MEXU,NMC,NY); 0.9 mi
from jct of San Juanito-Basaseachic road on road to Maguarichi, along flow-
ing stream, 19 May 1984, Ayers 393 (TEX); road to Mojarachi from the
San Juanito-Creel road, moist areas of steep slopes, 18 May 1985, Grimes
2862 (CIIDIR,MEXU,RM,TEX,UC,UCR,WIS). Mpio. Ocampo, Cascada de
Basaseachic, in large rocks at base of large boulders, near base of falls, 21
May 1984, Ayers 415 (TEX); Mpio. Guadalupe y Calvo, 81 km SW of El
Vergél toward Guadalupe y Calvo, 3.2 km S of bridge in Turuachi, deep area
of canyon, crevices and talus, 26 Aug 1983, past flr and frt, Nesom 4973
(MEXU,MICH,NMC,TEX); Mpio. San Pablo Balleza, 43.5 km SW of EL
Vergél on road to Guadalupe y Calvo, N-facing side of deep canyon with
pine-fir-oak, cliff crevices, loose talus below road, 26 Aug 1983, Nesom 4991
(ARIZ,ASU,CIIDIR,COLO,CAS,CHAPA,ENCB,F,GH,GUADA,K,MEXU,
MICH,MO,NMC,NY,RM,RSA,UC,US); 22.0 mi SW of El Vergeél, 0.1 mi N
of Rio Verde bridge, N-facing cliff above road, area of pine-oak woods, 25
Aug 1984, Nesom 5167 (TEX).

The epithet is grammatically distorted in reference to the emergent-
appearing rosette of basal leaves.

Erigeron eruptens is recognized among the species of sect. Polyactis by
its monocephalous, essentially scapose stems and large, densely cespitose,
basal rosettes of erect-ascending, pinnatifid leaves produced from numerous,
ascending caudex branches. The plants from southern Chihuahua apparently
are disjunct from the more northern population system and tend to have
larger leaves and heads as well as ascending-appressed pubescence and fewer
glands on the stems and phyllaries, but in other characters they appear to
represent the same species. In the Basaseachic area, E. eruptens is somewhat
similar to E. basaseachensis in habit but differs from it in its generally larger
size, lack of rhizomes, presence of glands, larger heads on scapose stems and
longer disc corollas.

Erigeron griseus (Greenm.) Nesom, Sida 9:224. 1982. Based on Achaetogeron
griseus Greenm,, Proc. Amer. Acad. Arts 41:254. 1905. Type: MEXICO,
Durango: Vicinity of the city of Durango, Apr-Nov 1896, E. Palmer
821 (holotype: GH!; isotypes: UC!,US!).

Bellis garciae S.F. Blake, Contr. U.S. Natl. Herb. 22:593. 1924. Type:
MEXICO, Durango: State of Durango, 1000 m, P. Ibana Garcia 310.
(holotype: US!). Achaetogeron garciae (S.F. Blake) Larsen, J. Wash-
ington Acad. Sci. 38:201. 1948.

Perennial herbs from fibrous roots, sometimes with short, fibrous-rooted

440 PHYTOLOGIA volume 66(5):415-455 June 1989

rhizomes, caudex simple or with several, short, ascending branches. Stems
11-36 cm tall, unbranched or sometimes with 1-4 branches on the lower
half, moderately thin-strigose, less commonly spreading on the lower half or
rarely from top to bottom, eglandular or very sparsely and inconspicuously
granular-glandular. Basal leaves usually deciduous by flowering, 7-130 mm
long, the blades obovate, attenuate to a petiole 1/2-2/3 as long as the leaf,
with 1-4 pairs of serrate or crenate teeth or obovate to lanceolate lobes, less
commonly entire, the cauline not clasping, becoming entire and sessile up-
wards, moderately strigose, mostly eglandular. Heads 7-17 mm wide, solitary,
the peduncles 1-14 cm long, often noticeably dilated just under the heads;
phyllaries 3.1-5.5 mm long, strigose to strigose-hirsute, minutely granular-
glandular, at least the inner with relatively broad, hyaline, often purplish
margins. Ray flowers 40-230, the corollas white or violet, (3.0-)8.0-14.9 mm
long. Disc corollas 2.0-3.5 mm long. Achenes 0.8-1.1 mm long, with 2-4
thick ribs, sparsely strigose; pappus a minute, cartilaginous crown less than
0.1 mm high, with a smooth, even apex, sometimes almost completely absent.
Chromosome number, n=9 pairs.

Central to southern Durango and adjacent Nayarit; grassy or rocky sites
in pine-oak to pine woodlands; 2250-2700 m; (Jun-)Jul-Oct. Map 7.

Representative collections examined: MEXICO, Durango: Mpio. El Salto,
6 mi W of Las Adjuntas on Hwy 40, 19 Aug 1981, Nesom 4446 (ARIZ,
ASU,CAS,COLO,ENCB,MEXU,MICH,NMC,NY,RM,TEX,UCR); Mpio. Du-
tango, Otinapa, 25 Jul-5 Aug 1906, Palmer 426 (CM,DS,NY,UC,US). Na-
yarit: between Santa Gertrudio and Santa Teresa, 8 Aug 1897, Rose 2087
(US).

Erigeron griseus is similar and closely related to E. wislizent. See com-
ments under that species.

The ray color in Erigeron griseus is mostly white; strikingly different,
violet-rayed forms are clustered mostly to the east of El Salto, but they
are also scattered elsewhere. As in E. wislizent, variation in other aspects
of morphology is not correlated with ray color and the color forms are not
given taxonomic recognition.

Nesom 4446 represents an unusually short-rayed and small-statured pop-
ulation of Erigeron griseus.

Erigeron griseus is superficially very similar to E. astranthioides De Jong
& Nesom, which also grows along Highway 40 in Durango. Both taxa are es-
sentially monocephalous and epappose, but the latter is related to the group
of species that includes E. forreri (E. Greene) E. Greene and E. galeottit (A.
Gray ex Hemsl.) E. Greene (De Jong & Nesom, 1982), rather than sect.
Polyactis. Erigeron astranthioides differs from E. griseus in its thin, scale-
leaved stolons (fragile and easily broken off during collecting), stems very
sparsely spreading-pubescent, leaves with glabrous to glabrate lamina, the

Nesom: Taxonomy of Erigeron sect. Polyactis 441

basal sharply attenuate to a distinct petiole, the cauline sessile, subclasping,
phyllaries thin-herbaceous from base to tip, obovate to oblong-obovate, ray
corollas non-reflexing, collecting appendages of the style branches (disc flow-
ers) lanceolate to narrowly triangular, 0.3-0.4 mm long and achenes glabrous
with thin nerves.

Erigeron inoptatus A. Gray, Proc. Amer. Acad. Arts 21:387. 1886. Type:
MEXICO, Chihuahua: on riverbank in sand, 150 mi N of Batopilas,
Aug-Nov 1885, E. Palmer 442 (holotype: GH!; isotype: US!).

Erigeron alcicornutus Greenm., Proc. Amer. Acad. Arts 41:255. 1905.
Type: MEXICO, Chihuahua: alluviums of Arroyo.Ancho, Sierra Madre,
15 Oct 1887, C.G. Pringle 1273 (holotype: GH!; isotypes: MEXU!,NY-
2 sheets!,PH!,RSA!,US!).

Annual herbs from a slender taproot, single-stemmed from the base.
Stems, leaves and phyllaries moderately to densely hirsute-pilose, densely
stipitate-glandular. Stem 24-175 cm tall, with 1-8 branches on the upper
half, usually with secondary branches. Basal leaves usually absent by flower-
ing; cauline leaves numerous, the basal petiolate, sessile above with clasping,
ampliate bases, the middle 2.5-8.5(-11) cm long, relatively unreduced in size
upwards, 7-66 mm wide (lobe tip to tip) with a midregion of even width,
margins with 1-5 pairs of lanceolate to obovate lobes, sometimes bipinnatifid,
with sinuses extending 1/3-2/3 to the midvein. Heads in a loose corymbose
capitulescence, 7-12 mm wide, on peduncles 490 mm long; phyllaries 3.5-
5.5 mm long. Ray flowers 325-450 in 3-4 series, corollas white, 6.2-9.5 mm
long, 0.2-0.5 mm wide, rarely very short or completely absent. Disc corol-
las 1.8-2.5 mm long. Achenes 0.8-1.0 mm long, with 2, thin nbs, glabrous;
pappus of 0-4 very brittle, basally caducous bristles 1/3-1/2 the disc corolla
height, the number of bristles variable among flowers of a single plant but
usually constant within one head, with an outer, minute, cartilaginous nm.
Chromosome number, n=9 pairs.

Central to southern Chihuahua and probably northern Durango; clear-
ings, pastures, disturbed sites, streambeds, grasslands or areas of pine or
pine-oak woods; 2150-2300 m; Aug-Oct. Map 6.

Representative collections examined: MEXICO, Chihuahua: Mpio. San
Pablo Balleza, town of El Vergél, ca 80 mi S of Parral on Hwy 24, 21
Oct 1986, Nesom 5762 (MEXU,NMC,NY,TEX); Mpio. Guerrero, ca 28 mi
SSW of La Junta on road to San Juanito, 18 mi S of jct with road to To-
mochic, 24 Aug 1981, Nesom 4489 (ARIZ,ASU,CAS,COLO,ENCB,F,MEXU,
MICH,MO,NMC,NY,RM,TEX,US); [Mpio. Guerrero], “Barranca Colorad,”
Sierra Gazachic, 35 km SW of Miiaca, 16-17 Sep 1934, Pennell 18925 (GH,
NY,PH,US).

Erigeron inoptatus is distinctive in its annual, single-stemmed habit, dense-
ly stipitate-glandular herbage, narrowly oblong, clasping cauline leaves, nu-

442 PH YTOLOGIA volume 66(5):415-455 June 1989

merous ray flowers with very narrow ligules, glabrous, thin-ribbed achenes
and reduced pappus. The plants of the type collection are somewhat atypical.
On the holotype, there is only a single series of ray flowers and these have
such short ligules that Gray assigned E. inoptatus to sect. Coenotus, which
at the time, contained species that have since been transferred to Conyza.
Ray flowers are completely lacking on the isotype.

The vestiture and leaf shape and base of Erigeron inoptatus suggest that
it is most closely related to E. seemannit.

Erigeron nacoriensis Nesom, sp. nov. Type: MEXICO, Sonora: Nacori,
[29° 04’N, 110° 03’W], 3750 ft, 1 Dec 1890, C.V. Hartman 271 (holo-
type: GH!).

E. eruptentem Nesom similis sed caulibus eglandulosis mani-
feste foliatis, capitulis minoribus, phyllariis eglandulosis, corollis
radii et disci multo brevioribus differt.

Perennial herbs from fibrous roots, producing a system of woody, as-
cending, distally thickened, caudex branches, each with a rosette of leaves.
Stems ascending-erect, 14-22 cm tall, unbranched or with 1-2 branches above
the middle, moderately pubescent with appressed to closely ascending tri-
chomes 0.2-0.6 mm long, eglandular. Leaves moderately strigose, minutely
but prominently granular-glandular; basal leaves 25-45 mm long, the blade
obovate with a rounded, mucronulate apex, pinnately divided with 2-4 pairs
of obovate lobes, 10-22 mm wide, sharply tapered to a petiole 5-20 mm long;
cauline leaves 10-26 mm long, elliptic-oblanceolate, 2-10 mm wide, entire or
with 1-3 shallow teeth, sessile or the lower with a petiole 1-3 mm long, not
clasping, relatively even-sized up to the capitulescence, where reduced to tiny
bracts. Heads 5-7 mm wide, solitary on peduncles 35-55 mm long; phyllaries
sparsely strigose, eglandular, in 2-3 subequal series, with broad, thickened,
lateral zones and narrow, scarious and sometimes slightly lacerate margins,
basally fused into a ring of tissue, 2.5 mm long, the outermost 1/3-1/2 as
long as the inner. Ray flowers ca 60-80 in 1 series, the corollas white, drying
white to light lavender, 4.8-6.0 mm long. Disc corollas 2.4-3.0 mm long. Ach-
enes 0.9-1.0 mm long, with 2, very thin nbs; pappus of 10-14 bristles with
an outer series of setae 0.1-0.2 mm high.

Known only from the type collection. Map 5.

Erigeron nacoriensis is similar to FE. eruptens in its habit of ascending
caudex branches with basal rosettes and mostly simple stems with solitary
heads and its relatively few ray flowers and pappus of bristles. It differs from
E. eruptens in its prominently leafy, eglandular stems, smaller heads with
eglandular phyllaries and much shorter ray and disc corollas. Further, in
the southern part of the range of E. eruptens, the plants have appressed-
strigose stem pubescence, but in west-central Chihuahua, where the range of
E. eruptens is closest to Nacori, the stems are hispid-pilose. The collection

Nesom: Taxonomy of Erigeron sect. Polyactis 443

of E. nacoriensis was made ca 200 km NW of the nearest collection of E.
eruptens. The collection was probably made in the Sierra Nacori, just east of
the town of Nacori. According to Marshall (1957), a deciduous oak woodland
would be found there at the elevation noted in the collection data. Other col-
lections made by Hartman (25 Nov 1890, 274-GH; 2 Dec 1890, 285-GH,US),
also labelled “Nacori,” were of E. neomezicanus, a species typically found in
oak to pine woodlands.

Erigeron neomezicanus A. Gray, Proc. Amer. Acad. Arts 19:2. 1883. Type:
UNITED STATES, New Mexico: Grant Co., mountains of the Copper
Mines, 1851, C. Wright 1170 (lectotype designated here: GH!; isolecto-
types: GH-2 sheets!,NY!,US!). E. delphinzfolius Willd. subsp. neomez-
icanus (A. Gray) Crongq., Brittonia 6:263. 1947.

Among the syntypes cited by Gray (“Wright, Bigelow, Thurber,
Palmer, Lemmon”), the Wright ones are distributed to various
herbaria. The lectotype is among the three sheets at GH origi-
nally annotated by Gray as E. neomezicanus.

Perennial herbs from strongly woody bases and roots. Stems 15-65 cm
tall, with 1-15 primary branches on the upper 1/2-1/3 of the stem, sometimes
with secondary and tertiary branches, moderately to densely strigose with
appressed to ascending trichomes, sometimes spreading at the base or over
the whole stem, eglandular or rarely minutely granular-glandular. Leaves
strigose, sometimes minutely glandular, the basal entire to toothed or pin-
natifid, usually absent at flowering, the cauline 11-55 mm long, the lower
attenuate to a petiole 1/4-1/2 as long as the leaf, not clasping, deeply pin-
natifid with 2-4(-5) pairs of lobes or sometimes slightly bipinnatifid, leaf
shape often highly variable within populations, 6-35 mm wide, gradually or
barely reduced in size upwards until the peduncles. Heads 7-12 mm wide,
on peduncles 3-55 mm long, in a loose, corymbose capitulescence; phyllar-
ies 3.6-4.9 mm long with the outermost 1/3-2/3 as long, strigose to hirsute,
the trichomes mostly arising from the midregion, eglandular or sometimes
minutely glandular. Ray flowers 70-150 in 1-2 series, corollas white, (2-)6-15
mm long. Disc corollas 2.5-3.3 mm long, often noticeably inflated and in-
durated above the constricted lower part. Achenes 1.0-1.3 mm long, with 2,
relatively thin, lateral ribs,commonly with 1-2 very thin ribs on the flattened
faces, sparsely strigose; pappus of (8-)10-12 bristles, with an outer series of
setae 0.1-0.2 mm high. Chromosome number, n=9, 18 pairs.

Arizona, New Mexico, Sonora and northwestern Chihuahua, rare to south-
ern Chihuahua; open, rocky sites, from grasslands into oak or pine woodlands,
often with madrofo, juniper, or fir; 1100-2700(-3000) m; (Jul-)Aug-Oct (-
Dec). Map 3.

Representative collections examined: MEXICO, Chihuahua: Guasare-
mos, Rio Mayo, 16 Sep 1935, Gentry 1828 (GH); Mpio. Guadalupe y Calvo,

444 PHY TOLOGIA volume 66(5):415-455 June 1989

summit of Cerro Mohinora, ca 13 mi SW of Guadalupe y Calvo, 27 Aug 1987,
McDonald & Martinez 2372 (MEXU,TEX,XAL); Mpio. Ocampo, along trail
to bottom of Cascada de Basaseachic, Nesom 5559 (TEX). Sonora: Sierra
de los Ajos, 29 Jul 1952, Marshall 87 (ARIZ,CA,UC).

UNITED STATES, Arizona: Cochise Co.: Chiricahua Mts.: ca 4 mi W of
Biological Station, just E of E Turkey Creek, 27 Aug 1981, Nesom 45126
(NY,TEX); 8 mi W of Biological Station, 27 Aug 1981, Nesom 4514 (CAS,
CIIDIR,CHAPA,DAV,NCU,NMC,OBI,RM,RSA,TEX,UCR). New Mexico:

Grant Co.: 3 mi N of Pinos Altos on Hwy 25, 17 Sep 1967, Hess 1497
(ARIZ,NCU).

In the Atascosa Mountains of southwestern Santa Cruz County, Arizona,
Erigeron neomezicanus commonly has ligules much shorter (2-6 mm long)
than typical for the species (6-15 mm long).

See the comments following Erigeron delphinifolius for observations on
the differences between it and FE. neomezicanus.

Cronquist (1947) treated Erigeron neomezicanus and E. oreophilus as
conspecific, and in most characters they are virtually identical. Erigeron
neomezicanus tends to have slightly shorter phyllaries and the achenes of-
ten have nerves on the flattened faces. The differences between them in
pubescence, however, are consistent and conspicuous and appear to be more
complex than if only a single species were involved (see key and comments
below).

In contrast to their extensive area of sympatry, E. neomezicanus is rare
in southwestern New Mexico and eastern Chihuahua, where L£. oreophilus is
abundant; but from northeastern Sonora, where FE. neomezicanus is abun-
dant, there have been almost no collections of E. oreophilus. In Arizona,
both taxa occur in some mountain ranges (e.g., the Chiricahua, Huachuca,
Santa Rita and Santa Catalina mountains), but in other ranges only one or
the other is known (e.g., E. neomezicanus in the Patagonia, Atascosa and
Sierra Ancha mountains; E. oreophilus in the Rincon, Baboquivari, Mazatzal
and Pinalefio mountains, including Mt. Graham). In the area of Basaseachic,
Chihuahua, E. neomezicanus is very rare; E. oreophilus is common. And E.
oreophilus extends much further south than E. neomezicanus.

The following couplet contrasts the two taxa. Illustrations of Type A, B
and C trichomes are found in Nesom (1976).

Stems, leaves and phyllaries with Type A trichomes usually absent to very
sparse, spreading, 0.6-2.0 mm long, averaging 1.0 mm, Type B tri-
chomes absent or rare, Type C (glandular) trichomes usually dense,
large (50 — 200um high), capitate and conspicuous ..... E. oreophilus

Stems, leaves and phyllaries moderately to densely pubescent with appressed
to spreading Type A trichomes 0.1-0.8(-2.0) mm long, averaging 0.4
mm, Type B trichomes abundant and prominent, Type C (glandular)

Nesom: Taxonomy of Erigeron sect. Polyactis 445

trichomes usually absent, minute (30 — 70~m high) and non-capitate
WHEN PLESCNG eee fanned aie ae eee Ee E. neomezicanus

In areas where Erigeron neomezicanus and £. oreophilus occur in close
proximity, there is little infra-populational variation in pubescence and plants
that might be considered of intermediate morphology may be present but
they are not abundant, despite Cronquist’s assertion that “E. oreophilus
grades directly into E. neomezicanus.” In the Chiricahua Mountains of
Arizona I have observed several populations of both taxa growing in close
proximity (e.g., Nesom 4512a and 45126) with little or no evidence of hy-
bridization. Plants that I have identified as EF. neomezicanus are much more
variable both in leaf morphology and vestiture than L. oreophilus, and most
putative hybrids are usually more similar to FE. neomezicanus - they have rel-
atively dense, spreading or appressed Type A trichomes and sparse, mostly
minute Type C trichomes on the phyllaries and sometimes on the upper-
most leaves and stems. One intermediate individual, for example, from the
Chiricahua Mountains (Roth s.n—TEX) is stipitate-glandular and has sparse,
appressed, Type C hairs.

Regional floras (Kearney & Peebles, 1951; Lehr, 1978; McDougall, 1973;
Martin & Hutchins, 1980) have maintained the two as separate species. The
unusually close correspondence of their overall geographic ranges, however,
and their morphological similarity lend credence to Cronquist’s hypothesis
that they are conspecific. If Cronquist is correct, the large area of sympatric
geographic distribution of the two forms implies that some form of complex
dimorphism or polymorphism may exist. But my own experience leads me
to the conclusion, albeit tentative, that there are two species, which may
hybridize, but not so frequently that the morphological boundary between
the taxa is extensively blurred.

Erigeron oreophilus Greenm., Proc. Amer. Acad. Arts 41:257. 1905. Type:
MEXICO, Chihuahua: Norogachi, southern part of the state, 8500 ft,
Nov 1885, E. Palmer 419 (lectotype [designated here]: GH!; isolec-
totypes: MEXU!,PH!,US-2 sheets!). £. delphinifolius Willd. subsp.
neomezicanus (A. Gray) Cronq. var. oreophilus (Greenm.) Cronq., Brit-
tonia 6:264. 1947.

Erigeron oreophilus Greenm. forma tenuilobus Greenm., Proc. Amer. Acad.
Arts 41:258. 1905. Type: MEXICO, Sinaloa: Sierra de Choix, 15 Oct
1898, E.A. Goldman 255 (holotype: GH!; isotype: US!).

Erigeron oreophilus Greenm. forma latilobus Greenm., Proc. Amer. Acad.
Arts 41:258. 1905. Type: MEXICO, Chihuahua: base of Mt. Mohinora,
12.8 km from Guadalupe y Calvo, 7000-7500 ft, 23-31 Aug 1898, E.W.
Nelson 4861 (holotype: GH!; isotype: US!).

Achaetogeron pringlei E. Larsen, J. Washington Acad. Sci. 38:200. 1948.

446 PHY TOLOGIA volume 66(5):415-455 June 1989

Type: MEXICO, Chihuahua: cool slopes, Sierra Madre, 10 Oct 1888,
C.G. Pringle 1625 (holotype: MO!; isotype: UC!).

Perennial herbs from strongly woody bases and roots. Stems 25-90 cm
tall, with 2-20 primary branches on the upper 1/2-1/3 of the stem, some-
times with secondary and tertiary branches, sparsely hispid-pilose with long
trichomes, prominently stipitate-glandular on at least the peduncles or up-
per portions of the stems. Leaves sparsely hispid-pilose, densely stipitate-
glandular on at least the upper, the basal entire to toothed or pinnatifid,
usually absent at flowering, the cauline 13-55 mm long, the lower attenuate
to a petiole 1/4-1/2 as long as the leaf, not clasping, deeply pinnatifid with
2-4(-5) pairs of lobes or sometimes slightly bipinnatifid, 6-35 mm wide, grad-
ually or barely reduced in size upwards until the peduncles, rarely the upper
coarsely toothed to entire, the blades then obovate. Heads 8-12 mm wide, on
peduncles 4-45 mm long, in a loose, corymbose capitulescence; phyllaries 4.5-
5.5 mm long with the outermost 1/3-3/4 as long, densely stipitate-glandular,
otherwise glabrous or very sparsely hispid-pilose. Ray flowers 75-130 in 1-2
series, corollas white, 814 mm long. Disc corollas 2.8-3.5 mm long, often
noticeably inflated and indurated above the constricted lower part. Achenes
1.0-1.2 mm long, with 2, relatively thin, lateral nbs, sparsely strigose; pap-
pus of (8-)10-12 bristles, with an outer series of setae less than 0.1 mm high.
Chromosome number, n=9 pairs.

Arizona, New Mexico, Sonora through Chihuahua, rare southward to
southeastern Durango; open, rocky habitats, often cliff ledges or crevices,
in oak to pine woodlands; 1250-2800(-3000) m; (May-)Jul-Oct(-Dec). Map
4.

Representative collections examined: MEXICO, Chihuahua: Rio Mayo,
19 Sep 1936, Gentry 2799 (ARIZ,GH,MO); 6.5 mi SW of El Vergél on road
to Guadalupe y Calvo, 27 Aug 1983, Nesom 4936 (TEX); La Bufa Mt. above
Cusihuiriachic, 31 Aug 1887, Pringle 1271 (GH,MEXU,MICH,MO,PH,US);
Mpio. Bocoyna, slopes of Rio Oteros W of Creel, 16 Oct 1977, Bye & Weber
8238 (LL). Durango: ca 20 air km WNW of Santiago Papasquiaro, 9 Jul 1983,
Worthington 10926 (TEX,UTEP); ca 50 mi NW of Santiago Papasquiaro,
19 Sep 1982, Spellenberg & Zimmerman 6768 (TEX); Mpio. Suchil, Rancho
Temascal, arroyo Los Indios, 14 Oct 1985, Alvarado 321 (TEX). Sonora: Dist.
Alamos, Arroyo Agua Blanco, 11 Oct 1933, Gentry 512 (ARIZ,DS,MICH);
Canon Internacional, 23 Aug 1940, White 3507 (MEXU,MICH).
UNITED STATES, Arizona: Cochise Co., ca 4 mi W of Biological Station,
just E of E Turkey Creek, 27 Aug 1981, Nesom 4512a (NY,RM,TEX); Gra-
ham Co., Pinalenio Mts., near entrance to Shannon CG and Heliograph Peak
Road, 29 Aug 1981, Nesom 4530 (ARIZ,COLO,MO,NY,TEX). New Mexico:
Catron Co., Hillsboro Peak, 19 Jul 1904, Metcalfe 654 (ARIZ,NMC,US).

I recognize Erigeron oreophilus var. dactyloides Greenm. as a distinct

Nesom: Taxonomy of FErigeron sect. Polyactis 447

species of sect. Polyactis, more closely related to EF. seemannu than to E.
oreophilus.

Plants from one locality in the Rio Mayo region of Chihuahua (Gentry
2799) are the most variable of any single collection of Erigeron oreophilus
studied. At least three distinctive morphotypes were present at this locality,
only one of which (ARIZ,MO) is typical of plants found over the rest of
the range. Two of the morphotypes have appressed Type A pubescence
on the upper stems. One of these has a cespitose habit, producing up to 8
decumbent or ascending, caudex-like branches from the base. These cespitose
plants (GH,MO) have densely glandular phyllaries but only Type B trichomes
on the peduncles. The other atypical morph (ARIZ,GH,MO) has a typical
habit but has conspicuous Type C glands mixed with appressed Type A
trichomes on the peduncles. All three forms are apparently diploid, judging
from the even-sized and highly stainable pollen, but the origin of the two
atypical forms is unknown. Other collections of E. oreophilus from the Rio
Mayo region (e.g., Gentry 2805-ARIZ) have been of typical plants. Typical
Erigeron neomezicanus also occurs in the Rio Mayo region (Gentry 1828).

Erigeron oreophilus is known from only few collections in Durango, where
the plants have very small glands.

Erigeron podophyllus Nesom, sp. nov. Type: MEXICO, Chihuahua:
Mpio. Ocampo, ca 16 km (air) ENE of Ocampo, ca 2.5 km S of village
of Basasaeachic, base of Cascada de Basaseachic, 28° 02’N, 107° 55’W,
barranca at base of falls of Rio Candamena, 17-20 Oct 1986, G. Nesom
5596 with L. Vorobik (holotype: TEX!; isotypes: ARIZ!,GH!,MEXU!,
MO!,NY!,US).

Ex speciebus sectionis Polyactis rhizomatibus longis crassis,
caulibus brevibus pauci-ramosis, foliis confertis in caulibus, obovati-
cuneatis dentatis in extremis distalibus, capitulis solitariis, et setis
pappo numerosioribus distinguenda.

Perennial herbs from long, remotely branched rhizomes, forming dense,
clonal populations. Stems 10-22 cm tall, quickly ascending at the rhizome
tips, sometimes minutely granular-glandular, moderately to densely but weak-
ly hispid with coarse to thin, white to translucent hairs, noticeably deflexed
on the lower portions, antrorsely appressed to ascending on upper pedun-
cles. Leaves sometimes clustered at rhizome tips but without a basal rosette,
sparsely strigose-hispidulous on both surfaces, the lower cauline oblong- to
obovate-cuneate to widely obovate, sometimes basally attenuate to a short,
petiole-like base, not clasping, with 1-3(-4) pairs of coarse teeth or shallow
lobes on the distal third, 7-18 mm wide, 10-35 mm long, gradually reduced
in size upwards. Heads 9-12 mm wide, solitary on naked peduncles 2-6 cm
long; phyllaries 4-6 mm long, stipitate-glandular, otherwise the outer sparsely

448 PHY TOLOGIA volume 66(5):415-455 June 1989

hispid. Ray flowers (50-)85-120 in 1-2 series, corollas white, drying white, 8
11 mm long. Disc corollas 2.5-4.0 mm long. Achenes ca 0.8 mm long, with
2 orange ribs, sparsely strigose; pappus of 11-17 basally caducous bristles,
slightly shorter than the disc corollas, with an outer series of linear scales
0.1-0.4 mm high.

Southwestern Chihuahua, endemic to the deep barranca at the base of La
Cascada de Basaseachic, ca 1000 m below the top of the falls in the open,
treeless area mostly in the spray zone, this dominated by E. podophyllus and
Aegopogon with other forbs; 1750-1800 m; flowering (Mar-)April-May and
again in October. Map 5.

Additional collections examined: MEXICO, Chihuahua: [Type locality]:
30 Mar 1975, McLaughlin 556 (ARIZ); 19 Aug 1984, Nesom 5107 with Lewis—
sterile but showing developing rhizomes (ARIZ,ASU,COLO,NMC,MEXU,
MO,NY,RM,RSA,TEX,US); 27 Apr 1986, Nesom 5438 with Spellenberg et
al. (F,TEX,RM,MO); 14 Oct 1984, R. & M. Spellenberg 7940 (TEX, dupli-
cates not seen at ASU,COLO,MEXU,NMC,NY,ID,RSA,UTEP).

Erigeron podophyllus is distinctive among all its relatives in sect. Polyactis
in its long, thick rhizomes, short- and single-stemmed habit, obovate-cuneate,
non-clasping leaves with a few, distal teeth or lobes and solitary heads. Also,
the large number of pappus bristles is unique in the section and remarkable
since E. podophyllus is probably the most narrowly restricted endemic and
has the most strictly imposed external barriers to dispersal of any species in
sect. Polyactis.

Erigeron polycephalus (Larsen) Nesom, Sida 9:224. 1982. Based on Achaeto-
geron polycephalus Larsen, J. Washington Acad. Sci. 38:200. 1948.
Type: MEXICO, Durango: San Ramon, 21 Apr-18 May 1906, E£.
Palmer 52 (holotype: MO!; isotypes: CM!,UC!,US!).

Achaetogeron corymbosus Larsen, J. Washington Acad. Sci. 38:201. 1948.
Type: MEXICO, Jalisco: canyons, moist rocks, Tuxpan, Feb 1904,
C.A. Purpus 527 (holotype: GH!).

Suffrutescent, perennial herbs 1.0-1.5(-2.4) m tall, from woody roots.
Stems usually with 3-12 primary branches on the upper half, these often with
secondary and tertiary branches, appressed-pubescent or sometimes spread-
ing, eglandular or rarely slightly stipitate-glandular. Cauline leaves sparsely
to densely strigose, sometimes minutely glandular, lower margins sometimes
long-ciliate, often tardily deciduous and deflexed on the lower stems, (3-
)8-90 mm long, the blades 2-35 mm wide, elliptic to elliptic-oblanceolate,
attenuate to a petiole 1/4-1/2 as long as the blade, margins serrate or cre-
nate with 411 pairs of mucronulate teeth, rarely reduced to mucros, rarely
with narrow, pinnate lobes. Heads 9-15 mm wide, 3-13 in a loose, bracteate
corymb, on peduncles 430 mm long; phyllaries 3-7 mm long, sparsely to
moderately hirsute-pilose, usually viscid-glandular. Ray flowers 60-110 in

Nesom: Taxonomy of Erigeron sect. Polyactis 449

1-2 series, corollas white, 6.5-15.0 mm long. Disc corollas 2.0-4.0 mm long.
Achenes 0.9-1.0 mm long, with 2, thick nbs; pappus of 8-11 caducous bristles,
with an outer, fimbriolate nb less than 0.1 mm high.

Western slope of the sierra in Durango, Sinaloa and Jalisco, mountains of
Colima, Michoacan and Guerrero, but apparently not on the Pacific slopes of
the latter two; steep habitats, commonly very moist, on mountainsides, cliffs,
tropical deciduous forest, oak-palm, oak, pine with a mixture of hardwoods,
to pine-fir or fir forests; 450-2850 m; (Nov-)Jan-Apr(-Aug). Map 2.

Representative collections examined: MEXICO, Colima: brecha, El Za-
pote, out of Hacienda San Antonio, 27 Mar 1966, de Puga 215 (ENCB). Du-
rango: 3-15 km toward El Salto from the Sinaloa boundary at El Palmito on
Hwy 40, 13 Apr 1965, McVaugh 23612 (CAS,DUKE,LL,MICH,MO,NY,US).
Guerrero: Mina, Aguazarca Filo, 21 Dec 1937, Hinton et al. 11314 (GH,MICH,
NY,UC,US). Jalisco: ca 15 mi SE of Autlan, 13 Apr 1949, McVaugh 10279
(DS,DUKE,LL,MEXU,MICH,NY,US). Michoacan: near Uruapan, 21 Jan
1926, Woronow 2916 (US). Sinaloa: Sierra de Surotato, Canyon de Tarahu-
mare, 17-24 Mar 1945, Gentry 7174 (GH,NY,MICH,PH,US).

Erigeron polycephalus is distinguished by its shrubby habit, corymbose,
small-bracteate capitulescence, serrate or crenate leaves with elliptic or elliptic-
oblanceolate blades and densely glandular phyllaries. It is a distinctive
species but highly variable in the orientation and density of its pubescence.

Erigeron rhizomactis Nesom, sp. nov. ‘Type: MEXICO, Chihuahua:
Mpio. Guadalupe y Calvo, N side of Cerro Mohinora, ca 13 mi SW
of Guadalupe y Calvo, 25° 57’N, 107° 03’W;; open, pine-fir woods with
scattered spruce, 2950 m, 20 Aug 1988, G. Nesom 6449 with A. McDon-
ald (holotype: TEX!; isotypes: ARIZ!,CAS!,COLO!,GH!,MEXU!,NY).

E. wislizent (A. Gray) E. Greene similis et arcte affinis pedun-
culis longis pubescentia appressa caulium superarum et pappo
coroniformi sed rhizomatibus valde tenuibus squami-foliiferis et
foliis amplectentibus differt.

Herbaceous perennials with a thickened caudex, producing thin rhizomes
up to 15 cm long. Stems 15-40 cm tall, usually simple, sometimes with 1-
2 branches from about the middle or below, moderately strigose-sericeous,
densely so under the heads, spreading to deflexed or retrorse near the base,
eglandular. Leaves moderately long-strigose, eglandular, the basal absent at
flowering but present at rhizome tips, mostly 2-9 cm long, the blades obovate,
attenuate to a petiole ca half the leaf length; cauline leaves oblong-lanceolate
to oblanceolate, sometimes narrowly so, entire or with 1-3 pairs of teeth on
the upper third, mostly 2-10 mm wide, 30-65 mm long, clasping, relatively
even-sized upwards. Heads 11-14 mm wide, solitary on naked peduncles 3-15
cm long; phyllaries 5-7 mm long, moderately hirsute-pilose, densely minutely

450 PHYTOLOGIA volume 66(5):415-455 June 1989

stipitate-glandular, at least on the distal half. Ray flowers 112-180 in i-
2(-3) series, corollas white, 11-16 mm long. Disc corollas 2.8-3.2 mm long.
Achenes oblong, mature size not observed, sparsely strigose, 2-ribbed; pappus
a hyaline corona of fused scales 0.1-0.2 mm high, without bristles.

Known only from the area around Guadalupe y Calvo in southern Chi-
huahua; pine-oak to pine-fir woods, margins, clearings, or in open woods,
usually in relatively deep and loose soil; 2450-3000 m; Aug-Oct. Map 7.

Additional collections examined: MEXICO, Chihuahua: Mpio. Guadalupe
y Calvo: [Type locality, near the peak], 27 Aug 1987, McDonald & Martinez
2340 (MEXU,NMC,TEX,XAL); ca 13 mi E of Guadalupe y Calvo, 4.5 mi W
of jct to Atascaderos, clearing in pine-oak woods, 2700 m, 24 Aug 1984, Ne-
som 5147a (MEXU,TEX,US); ca 11 mi E of Guadalupe y Calvo, 7.0 mi W of
jet to Atascaderos, at woods edge in area of pine-oak, 2590 m, 24 Aug 1984,
Nesom 5151 (MEXU,TEX); 10.9 mi W of jet to Atascaderos, ca 7 mi NE
of Guadalupe y Calvo, area of fir with pine on surrounding hills, roadbank,
2780 m, 24 Aug 1984, Nesom 5155 (ARIZ,MEXU,NY,TEX,US); ca 12.5 mi
SW of Guadalupe y Calvo on NW side of Cerro Mohinora, past turnoff to
peak, downslope on road to Sinaloa, roadbank in oak-pine woods with fir and
madrono, 2470 m, 22 Aug 1988, Nesom 6488 (MEXU,MO,NY,TEX).

Erigeron rhizomactis is very similar to E. wislizeni (A. Gray) Greene in
its long peduncles, appressed upper stem pubescence and coroniform pappus,
but it differs in its clasping leaves and very slender, scale-leaved rhizomes.
The rhizomes are fragile and easily disconnected, but if carefully done, un-
earthing these plants reveals extensive interconnections among individuals of
a colony. In my estimation, E. rhizomactis has probably been derived from
the E. wislizeni complex as a high-elevation isolate.

Erigeron seemannii (Schultz-Bip. ex Seem.) E. Greene, Pittonia 2:168.
1891. Based on Polyactidium seemannti Schultz-Bip. ex Seem., Bot.
Voy. Herald 301. 1856. Type: MEXICO, Durango: Sierra Madre,
NW of México, Nov-Jan 1849-50, Seemann 2026 (holotype: K!, MICH-
photo!; isotype: GH!). Boltonia seemanni (Schultz-Bip. ex Seem.)
Benth. & Hook., Gen. Plant. 2:269. 1873. Achaetogeron seemannit
(Schultz-Bip. ex Seem.) A. Gray ex Hemsl., Biol. Centr. Amer. 2:120.
1881.

Perennial herbs, fibrous-rooted, from a short, thick, erect caudex or very
short rhizome; stems, leaves and phyllaries sparsely to densely hirsute-pilose,
stipitate-glandular with trichomes 0.1-0.4 mm high. Stems 15-70 cm tall,
simple or usually with 1-6 branches on the upper 1/2-2/3. Basal leaves
usually deciduous by flowering, the cauline oblong-lanceolate to oblanceolate,
the largest 24-90 mm long, 8-37 mm wide, 2-3 times longer than wide, little or
very gradually reduced in size upwards until near the capitulescence, mostly
sessile with clasping to subclasping, slightly ampliate bases, margins with 1-

Nesom: Taxonomy of Erigeron sect. Polyactts 451

5 pairs of lanceolate, oblanceolate, or obovate lobes, sometimes bipinnatifid,
the sinuses extending from the edge 1/3-2/3 to the midvein, the blade mid-
region usually of even width. Heads 10-15 mm wide, in loose corymbose
capitulescence, on naked peduncles (0.5-)2.0-10.5 cm long; phyllaries 5.1-
7.6 mm long, glandular, otherwise sparsely hispid-pilose or lacking hairs.
Ray flowers 180-230 in 2-3 series, corollas white, 8.0-10.8 mm long. Disc
corollas 2.3-3.2 mm long. Achenes 1.0-1.3 mm long, with 2, thick, whitish
ribs, sparsely strigose; pappus of (1-6-)10-12 thick, caducous bristles ca 1/2-
4/5 the disc corolla height, or rarely the disc or disc and ray achenes without
bristles. Chromosome number, n=9 pairs.

Central Durango to southern Chihuahua; rocky soil, talus slopes, in areas
of oak, pine, or pine-oak woods; 2150-2800 m; Aug-Oct(-Nov). Map 6.

Representative collections examined: MEXICO, Chihuahua: Mpio. San
Pablo Balleza, 12 mi NE of El Vergél on Hwy 24 from Parral, 21 Aug 1981,
Nesom 4466 (ARIZ,CAS,CHAPA,COLO,DAV,ENCB,F,GH,GUADA,K,M,
MEXU,MICH,MO,NMC,NY,OBI,OS,RM,TEX,UCR,UC,US,WAT, WIS). Du-
tango: Mpio. Durango, ca 50 mi W of Durango and 15 mi NW of Los Coyotes
RR station, Rio Jarral canyon, 30 Sep 1962, Cronquist 9571 (GH,MEXU,
MICH,MSC,NY,TEX,US); Mpio. Durango, 6 mi W of Las Adjuntas on Hwy
40, 19 Aug 1981, Nesom 4445 (ARIZ,CAS, IBUG,MEXU,MO,NMC,NY,RSA,
TEX).

Erigeron seemannii is recognized by its perennial habit, prominently stipi-
tate glandular stems, leaves and phyllaries, stems with spreading pubescence
from base to tip, relatively large, clasping, lobed, oblong-lanceolate to oblance-
olate cauline leaves with broad midregions of even width, heads on long,
naked peduncles and thick-ribbed achenes with extremely brittle pappus
bristles that break off at the base at the slightest touch. The pappus is
without an outer series, although the minute stubs of the broken-off bristles
may falsely appear to represent one. In open habitats, the plants tend to
be sprawling (vs. erect), the heads and leaves smaller, the pubescence denser
and the glands smaller.

There appear to be two, widely separated population systems of Erigeron
seemannit. Erigeron dactyloides, the species mostly closely related to E.
seemannii, occurs as a third, equally separated population system still further
north in Chihuahua (Map 6).

Erigeron subacaulis (McVaugh) Nesom, Sida 9:225. 1982. Based on Achaeto-
geron subacaulis McVaugh, Contr. Univ. Mich. Herb. 9:361. 1972.
Type: MEXICO, Aguascalientes: Sierra del Laurel, near the Jalisco
border, ca 15-16 km SE of Calvillo, above Rancho de los Adobes, oak
forest, 2500-2700 m, 26-28 Aug 1960, R. McVaugh 18434 (holotype:
MICH!; isotypes: DUKE!,ENCB!,LL!,MICH!,NY!,US!).

Perennial herbs from fibrous roots, caudex simple or with a few, short

452 PH YTOLOGIA volume 66(5):415-455 June 1989

branches. Stems 7-40 cm tall, simple or with 1-3 branches on the lower 1/4-
1/2, sparsely to moderately strigose with closely appressed hairs, sometimes
ascending or spreading near the base, eglandular. Leaves sparsely arching-
strigose, eglandular; basal leaves 2-10 cm long, 420 mm wide, petiolate, the
blades oblanceolate to obovate, with 1-3 pairs of teeth or lobes, occasionally
entire; cauline reduced upwards, lanceolate to oblanceolate, entire, sessile
and non-clasping. Heads 8-12 mm wide, solitary on naked peduncles (1-)3-
10 cm long; phyllaries all with prominently scarious margins, the outer 4.5-
6.0 mm long, moderately hirsute-pilose, minutely punctate-glandular. Ray
flowers 50-130 in 1-2 series, the corollas 7.0-8.5 mm long, apparently not
reflexing with maturity. Disc corollas 2.2-2.9 mm long. Achenes ca 1.0-1.3
mm long, with 2, thick nbs, sparsely pubescent; pappus of 10-13 basally
caducous bristles 0.7-2.5 mm long, 1/3-2/5 the disc corolla height, with an
outer, blunt or barely fimbriate rng, less than 0.05 mm high.

Northern Jalisco and adjacent Zacatecas; areas of shrubby oaks or pine-
oak woods; 2100-2500 m; Aug-Sep. Map 1.

Additional collections examined: MEXICO, Jalisco: [topotype], Sierra
de] Laurel, near Calvillo, shrubby oaks, 2500 m, 27 Aug 1960, Rzedowski
14105 (ENCB). Zacatecas: Jalpa-Tlaltenango road, woods of Pinus and
Quercus, humid and shady arroyo, 2100 m, 2 Aug 1971, Diaz Luna 2353
(ENCB,MICH).

Erigeron subacaulis is recognized by its stems simple or few-branched on
the lower half, leaves entire to few-toothed and non-clasping, stem pubescence
appressed-strigose and eglandular, heads on long, naked peduncles, outer and
inner phyllaries with scarious margins and pappus of short bristles. On the
few plants I have studied, the ray corollas do not appear to reflex at maturity,
an anomalous feature within sect. Polyactis, but in other characters, the
species clearly belongs there. In habit, EF. subacaulis is most similar to £.
griseus, but the latter lacks pappus bristles altogether. Erigeron subacaulis
appears to be somewhat isolated from the other species of sect. Polyactis,
both morphologically and geographically.

Erigeron wislizent (A. Gray) E. Greene, Pittonia 2:168. 1891. Based on
Achaetogeron wislizent A. Gray, Mem. Amer. Acad. Arts 4:72. 1849.
Type: MEXICO, Chihuahua: Ilanos, Sierra Madre W of Chihuahua,
Wislizenus s.n. (holotype: GH!).

Achaetogeron pinnatifidus A. Gray, Proc. Amer. Acad. Arts 21:386. 1886.
Type: MEXICO, Chihuahua: cool, grassy slopes near Chihuahua, 19
Oct 1885, C.G. Pringle 303 (cited by Gray as Pringle 103) (holotype:
GH!; isotypes: CINC!,CM!,MEXU!,MICH!,NY-2 sheets!,PH,RSA!,US-
2 sheets!). Erigeron chihuahuanus E. Greene, nom. nov. Pittonia 2:169.
1891.

Achaetogeron purpurascens Greenm., Proc. Amer. Acad. Arts 39:94. 1903.

Nesom: Taxonomy of Erigeron sect. Polyactis 453

Type: MEXICO, Chihuahua: Sierra Madre, near Colonia Garcia, 8000
ft, 27 Jul 1899, C.H.T. Townsend & C.M. Barber 175 (holotype: GH!;
isotypes: MICH!,NY!,PH!,UC!,UNM-2 sheets!,US-2 sheets!). Erigeron
uislizent subsp. purpurascens (Greenm.) Nesom, Sida 9:225. 1982.

Perennial herbs with fibrous roots, from a simple caudex or short, thick
rhizome. Stems 1 (2-9), erect, 25-70 cm tall, usually with 1-7 branches on the
upper half, these usually with secondary and tertiary branches, moderately
to densely pubescent, spreading or slightly retrorse, sometimes antrorsely ap-
pressed on the upper 1/2-1/4 or on all the stem, eglandular or essentially so.
Leaves moderately arching-hispid, eglandular or essentially so; basal 1.5-15.0
cm long, oblanceolate to elliptic-oblanceolate or sometimes entire, petiolate,
coarsely toothed or lobed, usually absent at flowering; cauline gradually re-
duced in size upwards from the basal, lobed, toothed or entire, the bases
not ampliate or clasping. Heads solitary on naked peduncles 1-10 cm long,
7-12 mm wide; phyllaries 3.5-5.0 mm long with the outermost even or 1/2-
2/3 as long, moderately to densely hispid-pilose, eglandular to minutely and
inconspicuously stipitate-glandular, margins thick, whitish; receptacles shal-
lowly alveolate. Ray flowers 115-180 in 2-3 series, the corollas white, blue or
purple, 9.0-15.6 mm long. Disc corollas often with purple lobes, 2.2-3.0 mm
long. Achenes 1.0-1.8 mm long, with 2 (3-4), thick nbs; pappus a promi-
nent hyaline corona with an erose margin or a series of basally fused hyaline
scales 0.2-0.5 mm high, ray pappus rarely with a single barbellate bristle.
Chromosome number, n=9 pairs.

Chihuahua, Sonora, Sinaloa; margins, clearings or openings in oak, pine-
oak, or pine woods, also common in grasslands in large basins in the north-
central part of the state; 1700-2300 m; Jul-Oct. Map 7.

Representative collections examined: MEXICO, Chihuahua: [Mpio. Ma-
dera], Chuhuichupa, Aug-Sep 1936, LeSueur 966 (ARIZ,CAS- 2 sheets,GH,LL,
MEXU,PH,UC-2 sheets); Mpio. San Pablo Balleza, 5 km NE of El Vergél on
Hwy 24 from Parral, 21 Aug 1981, Nesom 4468 (ARIZ,CAS,CHAPA,COLO,
ENCB,F,GA,GH,GUADA,ILL,K,M,MEXU,MICH,MO,NCU,NMC,NY,OBI,
OS,RM,SD,TEX,UCR,UC,US,UTEP,WAT,WIS); 10.4 km NNE of El Vergél
on Hwy 24 from Parral, 23 Aug 1983, Nesom 4877 (ARIZ,CAS,MEXU,MO,
NY,RSA,TEX); Mpio. Guerrero, road to San Juanito, 5 mi S of jet with Hwy
16, 23 Aug 1981, Nesom 4485 (ARIZ,ASU,CAS,COLO,ENCB,GH,MEXU,
MICH,MO,NMC,NY,RM,TEX,UCR); Mpio. Guerrero, 9.8 mi W of Tomochic
on Hwy 16, 17 Aug 1984, Nesom 5069 (CAS,;MEXU,NMC,NY,TEX); Mpio.
Temosachic, 1.5 mi E of Yepachic on Hwy 16, 20 Aug 1984, Nesom 5128
(CAS,MEXU,NMC,NY,TEX). Sinaloa: Sierra Surotato, Ocurahui, 27-30 Aug
1941, Gentry 6218 (ARIZ,CAS,GH,MICH,NY,PH). Sonora: Cerro Saguar-
ivo, E of San Bernardo, 7-8 Aug 1935, Pennell 19609 (PH,US); Yécora, 3
Aug 1970, Pennington 92 (TEX).

454 PHY TOLOGIA volume 66(5):415-455 June 1989

Erigeron wislizent is recognized by the following characters: fibrous roots
from a short caudex or short, lateral rhizome; stems usually one from the
base, few-branched from near the middle, sometimes unbranched; receptacles
alveolate; and pappus a hyaline, laciniate-margined corona or series of basally
fused scales, 0.2-0.5 mm high, without bristles.

I earlier viewed Erigeron wislizeni as divided into several population sys-
tems deserving taxonomic recognition (Nesom, 1980; 1982). In particular, |
formally recognized the purple-rayed populations in northwestern Chihuahua
as subsp. purpurascens. Also, I tentatively (1980) recognized the plants from
Sierra Surotato, Sinaloa, as a distinct species.

After a great deal more field experience, however, I now perceive Erigeron
wislizeni as the most variable species of sect. Polyactis and recognize no in-
fraspecific taxa. Most conspicuously, plants of this species vary in the orien-
tation of stem pubescence (closely appressed to spreading), leaf shape (deeply
pinnatifid to entire or nearly so) and ray color (white to violet). Those with
pinnatifid leaves and spreading stem pubescence are particularly common in
west-central Chihuahua (see Nesom 5069; Nesom 4485 has pinnatifid leaves
with linear lobes and appressed pubescence); toothed-leaved plants with ap-
pressed or variably spreading to appressed stem pubescence are most common
elsewhere (see Nesom 4468, 4877 and 5128). Strongly violet-rayed plants are
restricted to northwestern Chihuahua (see LeSueur 966). There is too broad
a region of intermediacy in each of these characters to be able to identify
varieties without an unacceptable degree of arbitrariness.

Erigeron wislizent is very similar to E. griseus, even as Greenman rec-
ognized in the original description of the latter. Both taxa sometimes pro-
duce short, fibrous-rooted rhizomes, and both have non-clasping leaves, long,
naked peduncles and a pappus without bristles. They are the only two taxa
in sect. Polyactis that produce white and violet-rayed forms, and in both,
the orientation of the stem pubescence is variably appressed to spreading,
the leaf shape varies from nearly entire to deeply pinnatifid and there is com-
monly an extra, thick rib on each of the flattened faces of the achenes. In
southern Chihuahua, particularly, the habit and leaf morphology of E. wis-
lhizent closely approach those of typical E. griseus. Their geographic ranges,
however, apparently are disjunct; neither has been collected in northern Du-
rango. Morphologically, E. griseus differs (discontinuously) from E. wislizeni
in its pappus reduced to a blunt rib less than 0.05 mm high (vs. a laciniate,
hyaline corona 0.2-0.5 mm high) and inner phyllaries with relatively broad,
hyaline margins (vs. thick, whitish margins); plants of E. griseus also aver-
age smaller in size, have a stronger tendency to produce basally ascending,
unbranched stems and have punctate or weakly alveolate (vs. strongly alve-
olate) receptacles.

See the discussion under Erigeron rhizomactis and E. circulis for com-

Nesom: Taxonomy of Erigeron sect. Polyactis 455

ments on their relationship to E. wislizent.
ACKNOWLEDGMENTS

I thank Dr. B.L. Turner for comments on the manuscript and curators of
the cited herbaria for loans of specimens. Support for field trips in 1983 and
1984 was provided by the National Science Foundation.

LITERATURE CITED
Correll, D.S. 1959. A mule-train trip to Sierra Mohinora, Chihuahua. Amer.
Fern. J. 50:66-78.
Cronquist, A. 1947. A revision of the North American species of Erigeron,
north of México. Brittonia 6:121-302.
De Jong, D.C.D. & E.K. Longpre. 1963. Chromosome studies in Mexican
Compositae. Rhodora 65:225-240.

De Jong, D.C.D. & G.L. Nesom. 1982. Erigeron astranthiotdes (Asteraceae:
Astereae). a new epappose species from western México. Brittonia
34:285-289.

Gray, A. 1849. Plantae fendlerianae novi-mexicanae. Mem. Amer. Acad.
Arts ser. 2(1):1-116.

Greene, E.L. 1891. New or noteworthy species X. Pittonia 2:161-173.

Kearney, T.H. & R.H. Peebles. 1951. Arizona Flora. Univ. of California
Press, Berkeley.

Lehr, J.H. 1978. A Catalogue of the Flora of Arizona. Desert Botanical
Garden, Phoenix, Arizona.

MacDougall, W.B. 1973. Seed Plants of Northern Arizona. Museum of
Northern Arizona. Flagstaff.

Marshall, J.T. 1957. Birds of the pine-oak woodland in southern Arizona
and adjacent México. Pacific Coast Avifauna 32:1-125.

Martin, P.C. & C.R. Hutchins. 1980. A Flora of New Mexico, Vols. I & II.
J. Cramer, Braunschweig, Germany.

Nesom, G.L. 1976. A new species of Erigeron (Asteraceae) and its relatives
in southwestern Utah. Brittonia 28:263-272.

Nesom, G.L. 1980. Revision of the epappose species of Erigeron (Asteraceae
- Astereae). Ph.D. dissertation, Univ. of North Carolina, Chapel Hill.

Nesom, G.L. 1982. Nomenclatural changes and clarifications in Mexican
Erigeron (Asteraceae). Sida 9:223-229.

Pinkava, D.J. & D. Keil. 1977. Chromosome counts of Compositae from
the United States and México. Amer. J. Bot. 64:680-686.

Shinners, L.H. 1946. The genus Dichaetophora A. ee and its relationships.
Wrightia 1:90-94.

Phytologia (June 1989) 66(5):456-461

NEW SPECIES AND COMBINATIONS IN
MEXICAN VIGUIERA
(ASTERACEAE-HELIANTHEAE)

B.L. Turner
Department of Botany, University of Texas, Austin, TX, U.S.A. 78713

ABSTRACT

Two new species of Vigutera are described: V. gentryi B.
Turner from Sonora, México and V. torresii B. Turner from
Guerrero, México. The former belongs to the sect. Leighia of
Viguiera; the latter belongs to the Rhysolepis group (close to
V. morelensis). In addition, three new varietal combinations
are made: V. eriophora var. poblano (Panero & Schilling)
B. Turner, V. excelsa var. pachycephala (DC) B. Turner, V.
multiflora var. macrocephala (Heiser) B. Turner; and one new
variety is proposed: V. pinnatilobata var. megaphylla But-
terwick ex B. Turner.

KEY WORDS: Viguiera, Asteraceae, systematics, México.

A treatment of the Asteraceae for México (Turner & Nesom, in prep.) has
prompted description of the following new taxa and nomenclatural changes.

Viguiera torresii B. Turner, sp. nov., Figure 1. TYPE: MEXICO, Guer-
rero: 20.1 km E Petlaltina (68.1 km E of Chilapa on the road to Tlapa);
ca 170 m; “riparia en bosque de encino,” 14 Nov 1982, R. Torres C.
1897 [with E. Martinez S., P. Tenorio L. & C. Romero de T.] (holotype
TEX!; isotype MEXU).

V. morelensi Greenm. similis sed foliis majoribus sine ner-
vatura reticulata in paginis inferis et capitulis majoribus in pe-
dunculis ultimis multo longioribus differt.

Suffruticose perennial herb to 1 m high. Stems stiffly erect, densely pu-
berulent. Leaves alternate, gradually reduced upwards, those at mid-stem
mostly 8-10 cm long, 34 cm wide; petioles 5-15 mm long, the blade tapering
upon the petiole forming a narrow wing; blades ovate, 3-nervate from or near
the base, moderately pubescent above with harsh, broad-based hispid hairs,
the lower surface densely soft pubescent with mostly puberulent hairs,

Turner:

New Viguicra from Mexico 457
ye

—< : : To ea ecemenin mene
FSi re pe en en

Fig 1. Viguiera torresti, from holotype

458 PHY TOLOGIA volume 66(5):456-461 June 1989

the margins serrulate. Heads radiate, 3.0-3.5 cm across the expanded rays,
arranged 7-10 in lax terminal corymbose panicles, the ultimate peduncles
2-7 cm long. Involucres 3-4 seriate, campanulate, the bracts linear
lanceolate with acute apices, graduate, the inner series quite loose and
ciliate, usually reflexed for 3-6 mm at the apices. Receptacle convex,
paleate, the pales sclerose, tightly investing the achenes, somewhat trifid at
the apices. Ray florets ca 13, neuter, sterile; ligules ca 12 mm long, yellow.
Disk florets numerous (60+); corollas ca 6 mm long, the tube ca 1.5 mm
long, gradually merging into a tubular limb ca 4.5 mm long, the lobes ca 1
mm long. Achenes black, radially flattened, glabrous, ca 2.5 mm long, 1
mm wide, the pappus of 2 readily deciduous awns, 1.0-1.5 mm long, and 3-4
pairs of short lacerate deciduous scales ca 0.1 mm long.

The species is closely related to V. morelensis but the leaves are larger
and not especially reticulate veined beneath, while the heads are larger on
much longer ultimate peduncles.

It is a pleasure to name the species for the principal collector of the type
material, R. Torres C., who has added a number of notable species to the
Mexican flora.

Viguiera gentryi B. Turner, sp. nov., Figure 2. TYPE: MEXICO, Sonora:
Rio Mayo, Sapopa Canyon, “Upper Sonoran; oak slope,” 8 Feb 1935,
H.S. Gentry 1288 (holotype TEX!; isotypes F,LL!,TEX!).

V. montanae Rose similis sed involucris stramineis multo ma-
joribus (10-16 mm altis, 8-12 mm latis) bracteis 7-9 seriatis (vs.
5-7 seriatis) differt.

Stiffly erect suffruticose perennial (?) to 1 m high. Leaves mostly op-
posite, rarely alternate along the uppermost branches, 8-14 cm long, 1-3 cm
wide, sessile or nearly so; blades lanceolate, 7-9 times as long as wide, strongly
trinervate from the base, sparsely appressed strigose above and below, the
lower surface also minutely atomiferous glandular, the margins serrulate to
nearly entire. Heads 1-5 in a stiffly branched terminal capitulescence, the ul-
timate peduncles mostly 3-10 cm long, a few much reduced alternate leaves
along the peduncles. Involucres decidedly turbinate, straw colored, 10-16 mm
long, 8-12 mm wide, the bracts neatly and evenly graduate in 7-9 series, their
surfaces glabrous, their apices broadly obtuse or rounded, markedly ciliate
with silky white hairs. Ray florets 11-13, neuter, sterile, the ligules narrow,
yellow, 10-14 mm long. Disk florets 25-35, the corollas yellow, hispidulous,
ca 5 mm long, the tube ca 1 mm long. Achenes 5-6 mm long, appressed silky
pubescent, the pappus of 2 more or less equal awns, 3-4 mm long, between
these, 48 lacerate scales 1.0-1.5 mm long.

This is a very distinctive species what with its large, straw colored, 7-9
seriate, broadly turbinate involucres. It is apparently related to V. montana

459

Turner: New Viguiera from Mexico

Fig.1. Viguiera gentryi, from holotype

460 PH YTOLOGIA volume 66(5):456-461 June 1989

which Blake (1918) places in the small sect. Leighia.

According to label data, the vernacular name is “Ariosa” (Mexican) or “Wa-
cho-mo” (Indian); it also notes that “Medic. women put leaves on the stom-
ach to cause menses flow. .”. The collector describes the plant as an
annual 2-3 feet high, but I suspect the plant is a perennial, to judge from its
appearance.

Viguiera excelsa var. pachycephala (DC) B. Turner, comb. nov. Based
upon Tithonia pachycephala DC, Prod. 5:585. 1836.

Blake (1918) distinguished V. ezcelsa (Willd.) Benth. & Hook. from
V. pachycephala (DC) Hemsl. largely by leaf pubescence, the former being
pubescent along most of the veins and upon the surface, the latter pubescent
along the larger nerves and veins. I cannot distinguish two species. The type
of V. ezcelsa is from the Federal District of México; the type of V. pachy-
cephala is from Guanajuato City, Guanajuato. I distinguish between the two
varieties as follows:

1. Heads mostly 7-15 cm across the extended rays; mostly Pacific slopes
and western Central Plateau (Zac, Nay, Jal, Gua, Mic) ......... var.
pachycephala

1. Heads mostly 47 cm across the extended rays; mostly Central Plateau
(Sanz, Gua, Mex, Pue)! i). disc. cos. $e aoe eee var. excelsa

The two varieties appear to intergrade along their regions of contact.
Blake (1918) recognized yet two other varieties of V. ezcelsa: var. dilatatifolia
Blake from San Luis Potosi and var. megacephala (Robins. & Greenm.) Blake
from Guerrero. I include the former within my concept of var. ezcelsa; the
latter is accepted as a good taxon.

It should also be noted that Blake (1918) recognized V. pachycephala var.
simulans (Robins. & Greenm.) Blake, which appears to be synonymous with
V. hypochlora (Blake) Blake as noted by McVaugh (1984, p. 1059).

Viguiera eriophora var. poblano (Panero & Schilling) B. Turner, comb.
nov. Based upon Viguiera eriophora subsp. poblano Panero & Schilling,
Syst. Bot. 13:389. 1988.

In our forthcoming treatment of the Asteraceae of México, all meaningful
infraspecific morphogeographic segregates will be recognized as varieties.

Viguiera multiflora var. macrocephala (Heiser) B. Turner, comb. nov.
Based upon Heliomeris multiflora var. macrocephala Heiser, Indiana
Acad. Sci. 88:364. 1979.

The above combination is necessary since Heiser in Yates & Heiser (1979)
recognized Blake’s sect. Heliomeris as a distinct genus, as does H. Robinson
(1981). I prefer Blake’s broad circumscription of the genus.

Turner: New Vigutera from México 461

Viguiera pinnatiloba (Schultz-Bip.) Blake var. megaphylla Butterwick
ex Turner, var. nov. TYPE: MEXICO, Oaxaca: 20 mi NW of Nejapa,
dry subtropical deciduous low forests, 4300 ft, 30 Oct 1965, A. Cron-
quist & M. Sousa 10448 (holotype LL!; isotypes GH,MICH,NY,US).

V. pinnatilobae (Schultz-Bip.) S.F. Blake arcte similis sed
foliis majoribus (7-12 mm longis) quasi integris, marginibus tan-
tum sinuatis differt.

Additional collections examined: Oaxaca: hills at El Chacal, 28 km SE
Totolapan, ca 750 m, 8 Oct 1974, Cronquist & Becker 11224 (LL); 11 km E
Totolapan, ca 1100 m, 4 Oct 1974, Cronquist & Becker 11214 (LL); 30 m N
Oaxaca, 25 Dec 1969, Whiffen & Rodriguez 231 (TEX).

Butterwick (1975) knew this taxon only by the holotype; since her work,
3 additional collections (cited above) have been made in the region about the
city of Oaxaca, and all display the characters which she called to fore.

ACKNOWLEDGMENTS

I am grateful to Guy Nesom who provided the Latin diagnoses; and to
Guy Nesom and Andrew McDonald for critical readings of the manuscript.
Nancy Webber provided the illustrations.

LITERATURE CITED

Blake, C.F. 1918. A revision of the genus Viguiera. Contr. Gray Herb.
04:1-205.

Butterwick, Mary L. 1975. a systematic treatment of series Pinnatilobatae
of Viguiera. Masters Thesis, The University of Texas, Austin. 67 pages.

McVaugh, R. 1984. Compositae, in Flora Novo-Galiciana 12:1-1129.

Robinson, H. 1981. A revision of the tribal and subtribal limits of the
Heliantheae (Asteraceae). Smithsonian Contr. Bot. 31:1-102.

Yates, W.F. & C.B. Heiser. 1979. A synopsis of Heliomeris (Compositae).
Indiana Acad. Sci. 88:364-372.

Phytologia (June 1989) 66(5):462-464

NEW COMBINATIONS IN SECT. EFREMOSIS OF
VERNONIA (ASTERACEAE)

B. L. Turner, Department of Botany, University of Texas,
Austin, TX 78713, U.S.A.

ABSTRACT

Three new varietal combinations are made in Vernonta (sect.
Eremosis), these are: V. obtusa var. bartlettii; V. obtusa
var. parkeri and V. triflosculosa var. palmeri. So treated, V.
obtusa has three intergrading varieties and V. triflosculosa has
two intergrading varieties. A map showing the distribution of V.
obtusa is presented.

KEY WORDS: Vernonia obtusa, Vernonia triflosculosa, Eremo-
sis, systematics, México.

Preparation of a treatment of Vernonia for the Asteraceae of México has
necessitated the following new combinations within the sect. Eremosis.

Vernonia obtusa var. bartlettii (S.B. Jones) B. Turner, comb. nov. Based
upon Vernonia duncanit subsp. bartletti: S.B. Jones, Brittonia 25:110.
AOS:

Jones (1973) treated this taxon as a subspecies of his Vernonia duncantt.
I would include the latter within my concept of V. obtusa, the subsp. dun-
canit being synonymous with V. obtusa var. obtusa; the subsp. bartlettz is
somewhat more distinct and largely confined to the vicinity of Gomez Farias,
Tamaulipas. Consequently it is retained as a well-marked localized variety.
In foliage, V. obtusa var. bartletti: resembles the var. parker1, but the lat-
ter possesses smaller leaves and grades into the var. obtusa (cf below). The
geographical relationships of these several taxa are shown in figure 1.

Vernonia obtusa var. parkeri (S.B. Jones) B. Turner, comb. nov. Based
upon Vernonia obtusa subsp. parkert S.B. Jones, Brittonia 25:108. 1973.

As noted above, this taxon is only weakly differentiated from the var.
obtusa, both occurring in pine-oak forests from 1000-3000 m; the var. bartletti
is somewhat more distinct, occurring in mixed tropical deciduous forests at
lower elevations (600-1000 m). The several varieties may be keyed as follows:

462

Turner: New Vernonia from Mexico 463

@ var. obtusa
1

var. bartlettu

Fig. 1. Distribution of varieties
in Vernonia obtusa.

464 PHY TOLOGIA volume 66(5):462-464 June 1989

1. Leaves densely and persistently puberulent to tomentulose beneath;
pine-oak forests, southern Nuevo Leon and Tamaulipas to northern
Queretaro: . 6 .4in Aes ick nines 3. ene ties eee var. obtusa

1. Leaves glabrous or nearly so, usually somewhat glandular punctate be-
neath and sparsely pubescent along the major veins ............. (2)

2. Leaves lanceolate to oblanceolate, mostly 10-15 cm long; S Tamauli-
pas, tropical deciduous forests 600-1000 m
bartletti

2. Leaves ovate to ovate elliptic, mostly 5-8 cm long, Querétaro and
Hidalgo, pine-oak forests, 1000-2500 m............. var. parkeri

Vernonia triflosculosa H.B.K. var. palmeri (Rose) B. Turner, comb. nov.
Based upon Vernonia palmeri Rose, Contr. U.S. Natl. Herb. 1:101.
1891.

As noted by Mc Vaugh (1984), this taxon has been retained at the specific
level by most workers. However, he suggested that V. palmeri (and V. bar-
binervis Schultz-Bip. might best be treated as part of V. triflosculosa. Jones
(1973), however, retained V. barbinervis (as I do) but treated V. palmeri as a
subsp. of V. triflosculosa, noting that the two subsp. intergrade near regions
of contact. I agree with this observation and therefore treat V. palmeri at
the varietal level (varietal concepts are given in Turner, 1988).

ACKNOWLEDGMENTS

I am grateful to Guy Nesom and Andrew McDonald for critical reviews
of this presentation.

LITERATURE CITED

Jones, S.B. 1973. Revision of Vernonia section Eremosis (Compositae) in
North America. Brittonia 25:86-115.

Mc Vaugh, R. 1984. Vernonia triflosculosa, in Flora Novo-Galiciana 12:1037.

Turner, B.L. 1988. Comments upon, and new combinations in, Heliposis
(Asteraceae, Heliantheae). Phytologia 64:337-340.

- ia

5 00288 2395

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