143.  Dalea filiformis Gray

(Plate L)

Slender, often exiguous annual herbs (4) 7-30 (35) cm tall, sometimes flowering before the cotyledons wither, glabrous to the inflorescence (the leaf-rachis rarely minutely ciliolate), the subfiliform erect angular-ribbed greenish or purplish steins simple only when depauperate, commonly branching from base upward, or from near or above middle, the peduncles both leaf-opposed and terminal, the sparse foliage green, punctate beneath; leaf-spurs very short or 0; stipules narrowly subulate, 0.5-1.3 mm long; intrapetiolular glands spiculiform; post-petiolular glands minute, immersed; leaves petiolate (the petiole shorter than the first pair of leaflets), 1-3.5 (4) cm long, with 3 or 5 linear-filiform involute obtuse to minutely emarginate leaflets 5-23 mm long; peduncles filiform, (1.3) 2-8 cm long, surpassing the leaf; spikes often few-flowered, depressed-capitate becoming ovoid or shortly oblong, without petals 5-7 mm diam, the villosulous axis (2) 3-15 (20) mm long; bracts deciduous, rhombic-elliptic or -ovate to ovate-acuminate, 1.5-2.8 mm long, submembranous at base, thence livid and glandular, the lowest glabrous, the upper pilosulous dorsally, all ciliolate; calyx at anthesis turbinate, later distended by the pod, (2.5) 2.8-3.5 mm long, pilosulous with loosely ascending straight hairs up to 0.5-1 mm long, the tube (1.3) 1.5-1.8 mm long, its orifice oblique but not strongly recessed behind banner, the filiform, livid or castaneous ribs becoming prominulous, the membranous intervals glandless or charged with 1 (2) minute glands, the triangular-acuminate or -aristate, gland-spurred teeth 1.2-1.8 mm long (± as long or slightly shorter than tube); petals either concolorous, all pinkish- or reddish-purple, or the banner pale at anthesis and rubescent, all glandless, or the keel minutely gland-tipped, the epistemonous ones perched well below middle of androecium; banner 2.6-3.5 mm long, the claw 1.1-1.7 mm, the ovate or deltate-ovate blade 1.4-1.8 mm long, 0.9-1.6 mm wide; wings 1.8-2.4 mm long, the claw 0.5-0.8 mm, the obliquely lanceolate blade 1.2-1.8 (2) mm long, 0.5-0.7 mm wide; keel 2.4-3.2 mm long, the claws 0.8-1.5 mm, the ovate blades 1.4-1.9 mm long, 0.8-1.1 mm wide; androecium 10-merous, but the alternate stamens often reduced in size or obsolescent, the longer ones 2.5-3.5 mm long, free for 0.6-0.9 mm, the connective gland-tipped, the anthers pale, 0.25-0.3 mm long; pod obovoid, compressed, exserted from calyx-tube and ± as long as the teeth, 2-2.4 mm long, the style-base lateral, the valves hyaline in lower half, thinly papery distally; seed 1.5-1.9 mm long; 2n= 14 (Mosquin). — Collections: 42 (vi).

Shallow sandy and stony soils of open oak-pine woodland, coming out into grassland with juniper, 1680-2400 m (± 5900-8000 ft), rather common but inconspicuous and probably much overlooked, Sierra Madre Occidental from centr. Durango (mpos Durango and El Salto) n. through Chihuahua to Rio Bavispe in Sonora, and around the headwaters of the Gila River from s. Arizona (Patagonia, Huachuca, Chiricahua mts.) through s.-w. New Mexico (Pinos Altos and Mogollon mts.) and thence n.-w. across centr. Arizona (White Mts. Santa Catalina Mts. and Mogollon Rim) to Hualpai Mt. in Yavapai County. — Flowering August to November. — Representative: UNITED STATES. Arizona: Yavapai: Eastwood in 1929 (CAS, UC). Coconino: Hanson All (NY, OKLA). Greenlee: Pinkaava et al. 13,684 (NY). Pima: L. Benson 9041 (POM, UC). Cochise: Blumer 1638 (L, NY, W); Barneby 5155 (CAS, NY). New Mexico: Grant: Metcalfe 1461 (NY, US); Barneby 2515 (NY). MEXICO. Sonora: Babispe: Turner, Dodge & Mason 2103 (ARIZ, MEXU). Chihuahua: Madera: Pennell 19,225 (NY). Cd. Guerrero: Pringle 1211 (F, MEXU, NY). Cuauhtemoc: Ripley & Barneby 13,818 (CAS, DAO, MEXU, NY, US). Gral. Trias: Pennell 18,191 (GH, NY). Meoqui: Gentry 2549 (ARIZ, UC). Hidalgo del Parral: Townsend & Barber 211 (NY, US). Durango: V. Ocampo: Reveal & Hess 3021 (NY). Durango: Ripley & Barneby 13,499 (CAS, K, MEXU, MICH, NY, US). El Salto: Ripley & Barneby 13,994 (CAS, NY).

Dalea filiformis (threadlike, of stem and leaflets) Gray, Pl. Wright. 2: 39. 1853.— "Hillsides, near the copper mines [Santa Rita del Cobre, Grant Co.], New Mexico; Aug., in flower; Oct. in fruit. (992)." — Holotypus, collected by Charles Wright in 1851, GH! isotypi, NY, UC, US! — Parosela filiformis (Gray) A. Heller, Catal. N. Amer. Pl., ed. 2, 6. 1900.

Dalea hutchinsoniae (Mrs. W. Hutchinson) Jones, Extr. from Contrib. West. Bot. 18: 42. 1933.— "Pinos Altos mts. N[ew] M[exico]. Sept. 23, 1931..." —Holotypus (Morton, Contrib. U. S. Nat. Herb. 29: 102. 1945): Jones 28,709, dated Sept. 24, POM! isotypus, UC!

A frail, thinly leafy annual, D. filiformis is instantly recognized by its few (3-5, mostly 3) proportionately very long, threadlike leaflets of which the upper three form an exact trefoil. Other monocarpic members of sect. Parosela have the odd leaflet raised beyond the last pair. The species most like it habitally is D. transiens, differing technically in the free keel-petals of subgenus Dalea but more obviously in the more numerous (5-13) shorter and proportionately broader leaflets. Other annual daleas found in the range of D. filiformis all have leaflets of a broader type, either pilose or, if glabrous, then either much more numerous, or combined with persistent interfloral bracts.

The main range of D. filiformis lies in the forest belt of the Sierra Madre, but it has been traced out into the grasslands of the Conchos valley southeast of Ciudad Chihuahua and must be expected elsewhere in this environment.