Dalea neo-mexicana var. neo-mexicana

  • Title

    Dalea neo-mexicana var. neo-mexicana

  • Author(s)

    Rupert C. Barneby

  • Scientific Name

    Dalea neomexicana (A.Gray) Cory var. neomexicana

  • Description

    4a.  Dalea neo-mexicana (Gray) Cory var. neo-mexicana

    (Plate XXXI)

    Stems mostly 3-20 cm long, simple or 1-2-branched; foliage gray-silky, the leaflets pubescent above and beneath; leaves 0.8-2.5 (3.2) cm long, the cuneate-obcordate leaflets strongly gland-undulate; peduncles 0.3-3.5 cm long; calyx mostly 6.6-8 mm long, the tube 2.4-3.1 mm, the teeth (3.4) 3.8-5.2 (5.7) mm long; petals usually whitish variegated with dull crimson, rarely yellowish; 2n = 16 (Mosquin); n = 8 (Spellenberg, 1973). — Collections: 49 (i).

    Stony hills, knolls, and washes, in arid grassland transitional to desert, on a variety of sedimentary and volcanic substrates, rarely on gypsum, mostly 700-1750 m (2100-5300 ft), local but sometimes abundant, scattered over the northern Chihuahuan Desert from near 27° 30' N, n.-w. Coahuila and e. Chihuahua n.-ward from middle Conchos valley, and across Rio Grande (Bravo) into s. and w. trans-Pecos Texas (Brewster, Presidio, Hudspeth cos., n. to the Glass Mts.); unknown as yet from n. Chihuahua but reappearing near the Continental Divide in s.-w. New Mexico (Grant and Hidalgo cos.), thence w. to the edge of the Gila Basin in s.-e. Arizona (Cochise, e. Pima, Santa Cruz cos.) and s. to the headwaters of Rios Magdalena and Sonora in n.-e. Sonora; disjunct (and atypical; cf. discussion infra) on low hills along the Rio Grande, at it 180 m, in Webb County, Texas.—Flowering April to June, August to November.— Representative: UNITED STATES. Arizona: Peebles & Harrison 6940 (NY); Maguire 11,229 (NY); Peebles & Loomis 6995 (NY). New Mexico: Maguire 11,414 (NY). Texas: Wamock 13,838 (RENNER); Hinckley 649, 1282, 2778 (NY); Moore & Steyermark 1065 (NY, UC); Correll 20,660, 33,833 (RENNER). MEXICO. Sonora: Gentry 17,599 (US); Mahler 6089 (NY). Chihuahua: Stewart & Johnston 2017 (GH, TEX); Johnston & Mueller 100, (MICH, TEX); Mosquin 6569 (NY); Ripley & Barneby 13,893 (NY). Coahuila: Johnston & Mueller 1009 (MICH, TEX); Stewart 1748 (GH); Johnston 1814 (GH).

    Dalea neo-mexicana (Gray) Cory, Rhodora 38: 406. 1936, based on D. mollis var. ? neo-mexicana (of New Mexico, although described from Texas) Gray, Pl. Wright. 1: 47. 1852 ("Neo-Mexicana"). — "127...Hills beyond the Pecos, and the Pass of the Limpia; Aug." — Holotypus, collected by Charles Wright in 1849, GH! isotypi, NY, UC! — Parosela neo-mexicana (Gray) A. Heller, Cat. N. Amer. Pl. ed 2, 6. 1900. P. mollis var neo- mexicana (Gray) Macbr., Contrib. Gray Herb., New Ser. 65: 16. 1922.

    A modest little plant, but attractive because of its neatly crimped leaflets and lustrously silky racemes of calyces. In dry springs the plants may flower when the stems, all monocephalous, are only a few centimeters long, but following summer rain the mats of foliage can attain a diameter of 4 decimeters, each primary stem giving rise beyond the middle to one or two leaf-opposed peduncles or branchlets. The petals, all included within the plumose calyx-teeth, vary in color. They are commonly whitish tinged or tipped with dull crimson, but on gypseous soils in Coahuila Johnston noted them as "violet" or "yellowish" (I. Johnston 2017, 9371, GH), the last suggesting passage to var. megaladenia, also gypsophilous. The known range of var. neo-mexicana is twice interrupted. There is no record from the basin of Lagunas Guzman-Santa Maria in northwest Chihuahua, but the species is to be expected around its western periphery, for the populations in New Mexico and Arizona are indistinguishable from those in trans-Pecos Texas, and there are suitable habitats available the length of the Sierra Madre piedmont. The outlying station on lower Rio Grande in Webb County, Texas (12 mi n.-w. of Laredo, McCart 8386, OKLA) documents a more serious and perhaps racially significant disjunction. The one collection studied resembles var. neo-mexicana of trans-Pecos in habit and size of glands upon and subtending the calyx, but the calyx-teeth are only 3-3.5 mm long, as in var. megaladenia. The form of D. neo-mexicana that would be expected at low elevations in southern Texas is var. longipila, found only a short distance south of the border in Nuevo Leon, but the crisply undulate leaflets and short calyx-teeth of the Laredo plant are decisively different. More material is required before the status of this form can be settled.