Dalea verna

Title

Dalea verna

Author(s)

Rupert C. Barneby

Scientific Name

Dalea verna Barneby

Description

2.  Dalea verna Barneby

(Plate XXX)

Loosely cespitose, subacaulescent and shortly caulescent perennial herbs from a slender tortuous rootstock, silky-hirsute throughout with spreading-ascending straight lustrous spiral hairs up to 1.2-2 mm long, the numerous stems up to 3 cm long, simple and densely leafy, the leaves loosely rosulate, the foliage aromatic when crushed but not visibly glandular, the leaflets gray-silky on both sides, not or very obscurely punctate beneath; leaf-spurs almost 0; stipules narrowly lanceolate, papery or early becoming so, 2-5 mm long, hirsute dorsally, brown and glabrous within, glandless; intra- and post-petiolular glands 0; leaves 2-5.5 (or at early anthesis only 0.5-1.5) cm long, petioled, the rachis obscurely margined, the leaflets (3) 5-7 pairs, broadly obovate to obovate-cuneate or oblong-obovate, 3-10 (12) mm long, concave ventrally, keeled dorsally, the sessile terminal one usually smaller than the rest; peduncles appearing subradical, incurved-ascending, (0.5) 1-2.5 cm long, shorter than to about as long as the leaves; racemes moderately dense, the flowers at first ascending, then horizontal, finally declined, when pressed ± 2 cm diam, the hirsute axis becoming 1-3 cm long; bracts deciduous, narrowly lance-acuminate, ±5-7 mm long, at first thinly herbaceous, green or purplish, becoming dry and brownish, dorsally hirsute and sometimes minutely glandular, brown and glabrous within; pedicels 0.2-0.7 mm long, subtended by prickle-shaped glands up to 0.3 mm long; calyx (7.8) 8.5-10 mm long, barbately hirsute with lustrous hairs up to 2-2.7 mm long, the tube 3.2-3.5 mm long, not recessed behind banner, the ribs slender, livid, the plane pallid membranous intervals charged with 1 row of 2-5 tiny reddish glands, the deltate-aristiform gland-spurred teeth 4.5-6.8 mm long, plumose; petals bicolored, the banner whitish with green, early rubescent eye, the wings whitish or distally roseate, the keel brownish-crimson, all charged at base of blade but not at apex with small glands, the epistemonous ones inserted on the hypanthium rim but adnate through 1.2-2.2 mm to the androecium, not disjointing but marcescent, banner 5.6-5.8 mm long, the claw 2.6-2.7 mm, the sagittate-deltate, suberect blade 3.4-3.7 mm long, 2.9-3 mm wide, charged at base with transverse calluses but not recessed into a cornet; wings 6.3-6.7 mm long, the claw (including adnate part) 2.6-2.7 mm, the obliquely ovate or ovate-oblong, broadly auriculate blade 4-4.5 mm long, 2.1-2.2 mm wide; keel 7.7-10.2 mm long, the claws (including adnate part) 3.8-4.7 mm, the obliquely ovate blades 4.2-5.9 mm long, not puckered along interior margins, the exterior margins narrowly imbricate and adherent; androecium 10-merous, ± 8 mm long, the longer filaments free for ± 2.5 mm, the connective minutely gland-tipped, the pale yellow anthers 0.8-0.95 mm long; ovary densely pilose, the pod not seen. — Collections: 7 (4).

Open stony hills, gullied bluffs, and chalky breaks along stream-banks, on calcareous and metamorphic bedrock, 1650-2430 m (5500-8100 ft), forming colonies but highly localized, known from two restricted areas on the high grama-grasslands near the e. piedmont of Sierra Madre Occidental: n.-central Durango (mpos Villa Ocampo and nearby Villa Hidalgo) and s.-centr. Chihuahua (mpo Hidalgo del Parral); and w.-centr. Zacatecas (mpos Sombrerete and Sain Alto).—Flowering April and May, rarely again in fall. — Material: Chihuahua. Hidalgo del Parral: typus; Mosquin 6919 (DAO, sterile, topotype). Durango. Villa Ocampo: 12.5 mi s.-e. of Villa Ocampo, Ripley & Barneby 13,945 (NY, sterile). Villa Hidalgo: 30 mi s.-e. of Las Nieves, Mosquin 6919 (DAO, in part, mixed with D. simulatrix). Zacatecas. Sombre- rete: 2 mi e. of Sombrerete, Ripley & Barneby 13,462 (CAS, NY); Mahler 5746 (NY). Sain Alto: 3 mi s. of El Sauz, Ripley & Barneby s. n. in 1965 (NY, sterile).

Dalea verna (of spring) Barneby, sp. nov. ex affinitate D. neo-mexicanae et D. simulatricis, illam carina unguibus cum androecio basi coalita marcescenti, hanc petalis majusculis simulans, sed ab ambabus caule abbreviato vel subnullo dense rosulatim foliato, pedunculo subscapiformi, necnon foliolis subeglandulosis facile separanda. Dalea simulatrix cum D. verna hinc inde sympatrica ab ilia praeter caules evolutos tenellos procum- bentes ideo habitu toto dissimilis ulterius differt petalis deciduis carinaeque lamina glandu- lis etiam supra basin conspersa. — Herbae humiles multicaules vel multicipites pilis sericeis nitidis undique laxe pilosae habitu adspectu inter affines singulares. — Chihuahua. Hidalgo del Parral: open gravelly hills, ± 1930 rn (5800 ft), 5 mi w. of Hidalgo del Parral, 3 oct 1965, Ripley & Barneby 13,926. — Holotypus, NY.

A remarkable dalea, not readily recognized as such when out of flower, distinct from all others in its cespitose, subacaulescent growth-habit. Mature plants at the type-locality form loose cushions of silvery-gray leaf-rosettes up to 3-4 dm diameter, suggesting a stemless Astragalus rather than a Dalea, for the foliage, although aromatic when crushed, is not obviously gland-punctate. Near Sombrerete it is possible, in September or October, to find growing with it no less than six species of the genus (D. viridiflora, foliolosa, brachy- stachya, prostrata, laniceps, erythrorrhiza), all still in flower or newly fruiting, but the plants of D. verna are barren. In northern Durango and adjoining Chihuahua D. verna is directly associated with the related D. simulatrix, which differs most obviously in its weakly humifuse stems radiating from the root-crown, bearing a succession of leaf-opposed racemes, but also more importantly in flower-structure. In D. simulatrix the wings and keel disjoint from pockets on the androecial column, as in the desert annuals D. mollis and D. mollissima, whereas in D. verna, as in D. neo-mexicana, the claws are adnate to the androecium and the blades persist in the form of a little papery sac. Nevertheless it seems probable that D. verna and D. simulatrix must be genetically compatible, for west of Parral, where they grow together, a plant (Ripley & Barneby 13,926a, NY) intermediate in stature and appearance was found to have the marcescent keel of D. verna combined with deciduous wings and gland-sprinkled petals of D. simulatrix. This plant must almost certainly be a hybrid. In Durango (s.-e. of Villa Ocampo) where the two species again occur abundantly in the same habitat no sign of introgression could be found.

The accompanying illustration was prepared from the holotype, a plant flowering atypically in the fall. Fine specimens collected recently by W. Mahler near Sombrerete in full flower in the first week of April show the vernal aspect of the plant, when the rosette leaves are still undeveloped and much surpassed by the silky-pilose cones of flower.