2010. Taxonomy and distribution Dalea whghtii (Fabaceae). Phytoneuron 2010-45: 1-5.

TAXONOMY AND DISTRIBUTION OF DALEA WRIGHTII (FABACEAE)

Billie L. Turner

Plant Resources Center

The University of Texas

Austin, Tx 78712

ABSTRACT

Dalea wrightii A Gray is treated as a widespread and variable species consisting of two
infraspecific taxa: var. wrightii and var. warnockii (Tharp & Barkley) B.L. Turner. The former is a
more western element occurring in southern Arizona, southern New Mexico, western trans-Pecos
Texas, northeastern Sonora. Chihuahua, and western Coahuila. Var. warnockii is largely confined to
the easternmost trans-Pecos Texas, eastern Coahuila, and closely adjacent Nuevo Leon, Mexico. The
two taxa appear to intergrade in regions of near-contact, hence their treatment at varietal rank.
Morphological characters that mark the taxa are discussed, and a map showing their distribution is
provided.
KEY WORDS: Dalea, D. wrightii, Texas, New Mexico, Arizona, Mexico

Barneby (1977), in his masterful treatment of Dalea for North American, treated D. wrightii
as monotypic, noting that the closely related Dalea subulicola T. Brandegee (including Parosela
warnockii Tharp & Barkley) seemed unworthy of nomenclatural recognition and that the present
author concurred with his taxonomy, which was so at the time (Turner 1959). Subsequently,
however", in my Atlas of the Vascular Plants of Texas (Turner et al. 2003) I recognized P. subulicola
as distinct and treated and mapped it as a valid taxon at varietal rank, using as the basionym the
Texan eponymee (Barton Warnock) and authors Benjamin Tharp and Fred Barkley — D. wrightii
var. warnockii. The present paper further documents that taxonomy.

DALEA WRIGHTII A Gray, PI. Wright. 1: 49. 1850. Parosela wrightii (A Gray) Vail, Bull.

Torrey Bot. Club 24: 16. 1897. TYPE: USA. Texas. Jeff Davis Co.: eastern part of county
near Barilla Springs, Aug 1849, C. Wright 134 (holotype: GH).

Barneby (1977) has given an excellent description of the species and this need not be
repeated here. The following will help delimit the varieties concerned:

KEY TO VARIETIES

1. Leaflets mostly 2-3 times as long as wide, their apices mostly acute or rarely narrowly obtuse;
western Coahuila and western Trans-Pecos, Texas, westward to Arizona and Sonora .... var. wrightii
1. Leaflets mostly 1-2 times as long as wide, their apices mostly obtuse; eastern trans-Pecos Texas,
Coahuila, and western Nuevo Leon var. warnockii

Var. WRIGHTII Fig. 1.

This is a relatively distinct taxon throughout its range, but occasional plants approach var.
warnockii, especially in southeastern Chihuahua, across from the trans-Pecos region of Texas (e.g.,
Stewart 612, Stewart 992, TEX).

Dalea parrasana T. Brandegee superficially resembles var. wrightii, but the two taxa are
readily distinguished by their floral features, these brought to the fore by Barneby (1977). Dalea

Turner: Taxonomy of Dalea whghtii

wrightii var. warnockii occurs with D. parrasana in the Parras region of southern Coahuila (the two
taxa mounted on the same sheet [Henrickson 6160, TEX]). It is possible that the occasional hybrid
between these might occur.

In short, Dalea wrightii var. wrightii and var. warnockii appear to be distinct regional taxa
(Fig. 3), the former more western, the latter more eastern, with occasional signs of intergradation
along regions of near-contact.

Var. WARNOCKII (Tharp & Barkley) B.L. Turner, Sida, Bot. Misc. 24: 7. 2003. Parosela

warnockii Tharp & Barkley, Anales Esc, Nac. Ci. Biol. 4: 284. 1946. TYPE: USA. Texas.
Pecos Co.: [between] Fort Stockton [and] Sheffield, 3 Jun 1940, B.C. Tharp s.n. (holotype:
TEX). Fig. 2.

Dalea subulicola T. Brandegee, Univ. Calif. Publ. Bot. 4: 179. 1911

The most obvious difference of this variety from the typical taxon is that of leaf shape, as
noted in the above key to varieties. Barneby also noted that in var. warnockii, the vestiture appears to
be more nearly tomentose, which is so for most of the plants occurring in the USA and in much of
Mexico. Nevertheless, seemingly intermediate plants may be found in southern Coahuila (e.g., 5 mi
W of Saltillo along route 60, Correll & Johnston 21391 [LL]; El Kelso, Ramos Arizpe, gypsum
hillside, Hinton et at. 25972 [TEX]). Whether such intermediates suggest past or current
hybridization is moot.

ACKNOWLEDGEMENTS

The dot maps are based upon specimens on file at LL-TEX and SRSC — thanks to the

curators for their examination. Guy Nesom kindly reviewed the paper.

LITERATURE CITED

Barneby, R.C. 1977. Dalea, in Daleae imagines. Mem. New York Bot. Card. 27: 135-587.
Turner, B.L. 1959. The Legumes of Texas. Univ. Texas Press, Austin

Turner, B.L,, H. Nichols, G, Denny, and O. Doron. 2003. Atlas of the Vascular Plants of Texas, Vol.
1 (Introduction, Dicots). Sida, Bot. Misc. 24: 1-648.

Turner: Taxonomy of Dalea wrightii 3

Figure 1. Dalea wrightii var. wrightii (from near the type locality, Jeff Davis Co., Texas).

Turner: Taxonomy of Dalea wrightii 4

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Figure 2. Holotype of Dalea wrightii var. warnockiii (= Parosela warnockii) (Pecos Co. Texas).

Turner: Taxonomy of Dalea wrightii 5

Figure 3. Distribution of the two varieties of Dalea \