Dalea bicolor var. argyrea

  • Title

    Dalea bicolor var. argyrea

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Dalea bicolor var. argyrea (A.Gray) Barneby

  • Description

    108b.  Dalea bicolor Humboldt & Bonpland ex Willdenow var. argyrea (Gray) Barneby

    (Plate C)

    Low shrubs, up to 9 dm tall, mostly less, the stems usually erect, forming plants of ± rounded bushy outline; leaves 1-3.5 cm long; leaflets (2) 3-6 pairs, (2) 3-9 mm long, densely satiny- or velvety-pilosulous both sides, rarely glabrescent and greenish; spikes comparatively compact, ovoid becoming cylindroid, without petals 8-10 mm diam, the axis 0.5-4 cm long; calyx (3.5) 3.8-5 mm long, densely short-pubescent, the tube 2.6-3.2 mm, the dorsal tooth 0.8-2 mm long; petals of var. bicolor. — Collections: 30 (ii).

    Open stony hills and benches of canyons, ascending (s.-ward) into the oak-belt, locally plentiful, sometimes forming thickets, 450-2070, strongly but not obligately calciphile, w. Texas (n.-w. from mouth of Devils River, Val Verde to Culberson Co.) and immediately adjoining s.-e. New Mexico s. through detached ranges in Coahuila to the n. Sierra Madre Oriental in Nuevo Leon and adjoining Tamaulipas, extending s. to or slightly beyond the Tropic of Cancer .—Representative: UNITED STATES. New Mexico. Eddy: Steiger 461 (NY); Barneby 2594 (NY). Texas. Culberson: Wamock 9565 (OKLA, TEX); Waterfall 5754 (NY, OKLA). Presidio: Hinckley 830 (NY). Brewster: Wamock 21,016 (TEX). Val Verde: Cory 37,972 (TEX). MEXICO. Coahuila: V. Acuna: Marsh 581 (F, GH, OKLA). Melchor Muzquiz: Stewart 1308 (GH); Marsh 1349 (GH, OKLA, TEX). Cuatro Cienegas: Johnston 8381 (GH). Arteaga: Ripley & Barneby 13,285 (CAS, NY). Nuevo Leon. Monterrey: Edwards s. n. (NY). Tamaulipas. Cd. Victoria: Gentry 6753 (ARIZ, UC, US). Jaumave: von Rozynski s. n. in 1931 (NY, UC). : Berlandier 783 (NY, P), 2203 (F, NY, P).

    Dalea bicolor H. & B. ex Willd. var. argyrea (Gray) Barneby, stat. nov., based on D. argyrea (silvery, of the foliage) Gray, PI. Wright. 1: 47. 1852.— "High hills near the San Pedro [now Devils] River [Val Verde Co., Texas], abundant; July. (San Antonio de las Alanzanes, Mexico, Gregg, no. 357. Southern frontiers of Texas, Dr. Bigelow)." — Holotypus, C. Wright 131, collected 30 Jul 1849, GH! isotypi NY, OXF! paratypi (Gregg, Bigelow), GH! — Parosela argyrea (Gray) A. Hell., Catal. N. Amer. PI., ed. 2, 5. 1900.

    Parosela paysoniae (Lois Butler, 1895- , m. Edwin Blake Payson) L. O. Wms., Bull. Torrey Club 61: 252. 1934.— "Low B. Payson 37, September 27, 1931, rocky slopes near Carlsbad Caverns..." — Holotypus, RM!

    Although Gray believed D. argyrea to be very distinct from all known North American species with the possible exception of D. argentea Mart. [ now identified as D. tomentosa (Cav.) Willd.], it is in reality only to be distinguished with difficulty from D. bicolor var. bicolor, and then only by placing an inordinate emphasis on the silvery or satiny pubescence of the foliage, a notoriously weak differential character in Dalea. With silvery pubescence we find generally associated a relatively compact and short spike, but this is not diagnostic. As already noted under var. bicolor, the limit between it and var. argyrea is indefinite in west-central Coahuila, although all known collections from the Serranias del Burro seem to be of the argyrea type. In Jaumave valley, where the variety has been collected often, there occurs a variant with greenish foliage (Graham & Johnston 4145, UC) which cannot be separated technically from some forms of var. bicolor from the interior plateau. Thus var. argyrea has little more claim to taxonomic recognition than several minor variants already described briefly under var. bicolor. In southeastern New Mexico Spellenberg (no. 3675, NY) found a form of var. argyrea with prostrate-ascending woody stems that rooted where in contact with the soil, in the manner of D. frutescens.