101c.  Dalea tomentosa (Cavanilles) Willdenow var. mota Barneby

(Plate XCIV)

Up to 1-1.2 m tall, the virgate, purplish, shaggy-pilosulous stems branching distally into a relatively few-headed and open panicle of subglobose or shortly and plumply oblong spikes, these broad in context of the species, short secondary branchlets developing, if at all, only late in the season; bracts and calyx densely silky-barbate throughout; flowers in the size-range of var. tomentosa; calyx 4-4.3 mm, the tube 2-2.4 mm, the dorsal tooth 1.6-1.8 mm long; banner 3.7-4.6 mm long; keel 4.5-5.1 mm long, the claw 1.7 mm, the blades 2.9-3.4 mm long, 1.8-2 mm wide; androecium 5-5.5 mm long, bearing the epistemonous petals at points 1.3-1.7 mm above hypanthium. — Collections: 5 (o).

Arid or sometimes moist rocky hillsides in oak-pine and oak-madrono woodland, sometimes on limestone, 1200-1740 m (4000- 5800 ft), local, w. slope of Sierra Madre Occidental in s. Sonora (Sas. Charuco and Saguaribo and vicinity, on Rio Mayo) and n. Sinaloa (Sa. Surutato).— Flowering late October to March. —Material: Sonora. Alamos: Canelas, Gentry 2021 (F, GH); Curohui, Rio Mayo, Gentry 2143 (ARIZ, F, K, MEXU, UC). Sinaloa. Sinaloa de Leyva: n.-w. of Los Omos, Breedlove & Kawahara 17,080 (NY). Badiraguato: Los Ornos, Breedlove & Kawahara 16,806 (NY).

Dalea tomentosa (Cav.) Willd. var. mota (the vernacular name) Barneby, var. nov., quoad florum magnitudinem coloremque cum var. tomentosa congruens sed panicula pauci-capitata aperte corymboso-cymosa nec thyrsiformi, spicis latiusculis 10-12 (nec ±7-9) mm diam., et praesertim calyce toto longe densissime barbato-piloso, pilis sericeis saltern 1 mm longis absimilis. — Sinaloa. Badiraguato: open calcareous slopes in oak forest, 4000 ft., Tierra Blanca, March 4, 1940, Howard Scott Gentry 5804. — Holotypus, NY; isotypi, ARIZ, MICH.

The cited collection from Curohui, Sonora, dating back to 1935, was examined by Standley and annotated as representing a new species. The name was left unpublished, but the epithet mota, heard in Sonora by Gentry, is appropriately taken up even if at a lower taxonomic level. Gentry’s collections were all distributed as D. tomentosa with mark of interrogation, expressing the affinity of the plant and recognition of its distinctness On account of the relatively few and plumply oblong or subglobose flower-spikes arranged in an open panicle rather than a narrow thyrse, var. mota is immediately distinguishable from var. tomentosa, but there seem to be no solid differential characters in the flower or foliage. Shorn of its beautiful silky-barbate vesture the calyx of var. mota is essentially like that of var. tomentosa. Furthermore, late in the year’s growth-cycle some short leafy branchlets are developed below the primary panicle, these closely resembling the short- shoots in the thyrse of var. tomentosa and var. psoraleoides. It is noteworthy that the last- named occurs shortly southward from Sierra Surutato on the main range of Sierra Madre east of Mazatlan, whereas var. tomentosa, which it more closely resembles in size and coloring of the flowers, is not known from north of Tepic in Nayarit. Thus var. mota is greatly isolated from the aspect of D. tomentosa to which it appears most nearly related. The dense silvery pubescence of the leaves somewhat suggests the kindred D. greggii but the whole habit of the plant is so different that a genuinely close relationship seems unlikely.