Dalea transiens

Rupert C. Barneby

30. Dalea transiens Barneby

(Plate L)

Erect, very slender, sparsely leafy annual herbs 1-5.5 dm tall, glabrous to the silky-pilosulous spikes, the stems angular-ribbed, purplish at base, distally green and charged with a few small, scattered glands, branching from near the base or (depauperate) only from above the middle, the foliage bicolored, the leaflets yellow- green above, paler or subglaucescent and punctate beneath; stipular spurs 0.4-0.8 mm long, the blades deltate short-acuminate 0.3-1 mm long, livid or castaneous, sub- glandular, deciduous; intrapetiolular glands spiculiform; post-petiolular glands small, pale, immersed or lenslike; leaves drought-deciduous, (0.8) 1-3 (3.5) cm long, shortly petioled, the narrowly obtuse-margined rachis not or faintly punctate, the 5-11 (13) leaflets distant, linear-oblanceolate or -elliptic, emarginate, thick-textured and loosely involute, (2) 3-8 mm long; peduncles filiform, both terminal and leaf-opposed, 1.5-9 (11) cm long; spikes moderately dense, oblong to cylindroid, without petals (or pods) 5.5-7 mm diam, the villosulous axis becoming (0.3) 0.5-2 cm long; bracts early deciduous, narrowly elliptic- or lance-acuminate, dorsally livid, glandular, pilosulous; calyx 2.7-3.2 mm long, silky-pilosulous with fine, ascending hairs up to 0.8-1 mm long, the tube 1.5-2 mm long, at anthesis turbinate, ± 1.5 mm wide at orifice, in fruit broader, campanulate, the dorsal sinus recessed, the ribs subfiliform, livid, the flat membranous intervals charged with 1 row of 3 small yellowish or brownish glands, the narrowly triangular short-acuminate livid gland-spurred teeth 1-1.4 mm long; petals bicolored, the banner cream and pink, the inner ones pink-lilac, perched near middle of androecium, the keel-petals free even in vernation; banner 2.4-3 mm long, the claw 1.3-1.8 mm, the deltate-cordate, subacute blade (0.8)1.2-1.5 mm long, (1) 1.2-1.6 mm wide; wings 1.6-2.5 mm long, the claw 0.4-0.7 mm, the obliquely lance-ovate blades 1-1.5 mm long, 0.5-0.8 mm wide; keel-petals a trifle longer or shorter than the wings, the claw 0.8-0.9 mm, the obliquely ovate, obscurely auriculate blade 1.1-1.4 mm long, 0.7-0.8 mm wide; androecium 5-7-merous, 2.7-3 mm long, at least 5 and often all stamens fertile, the longer filaments free for it 0.7 mm, the connective minutely gland-tipped, the pallid anthers 0.25-0.3 mm long; pod exserted from the calyx-tube, 2.4-2.8 mm long, hyaline at base, pilosulous distally; seed green-ochraceous, 1.7-2 mm long. — Collections: 3 (ii).

Shallow soil of depressions on flat-topped mesas or on open stony hillsides among grasses, 1920-2130 m, local but inconspicuous and possibly overlooked, known only from the e. piedmont of Sierra Madre Occidental, along and near the line of oak- woodland transitional to grassland, in central Durango. — Flowering September to November. — Material: Durango. Durango: "Durango and vicinity", Palmer 795 in 1896 (UC); 10 mi. s.-w. of Ciudad Durango (type). Canatlan: Donato Guerra, ± 41 mi n. of Ciudad Durango, Ripley & Barneby 13,958 (CAS, NY, US).

Dalea transiens (transient, of short duration) Barneby, sp. nov., a D. leporina caulibus filiformibus, foliolis 2-5 (6)-jugis, necnon floribus minutis (vexillo 2.4-3 mm tantum longo) facile separanda. A D. filiformi, habitu comparanda, foliis pinnatis nec 3-foliolatis foliolis linearibus sed haud vero filiformibus, carinaeque petalis ab initio inter se liberis, a D. polygonoide bracteis cito delapsis calycisque forma ac glandulis minutis longius ut videtur abstat. — MEXICO. Durango: shallow soil of depressions on top of mesa, 2130 m (± 7100 ft), in the first benches of Sierra Madre ± 10 mi (15 km) s.-w. of Ciudad Durango, nov 9, 1963, Ripley & Barneby 13,481. — Holotypus, NY! isotypi, CAS, GH, K, MICH, US!

A delicate annual herb with threadlike but wiry stems and narrow spikes of minute flowers, always inconspicuous but becoming especially well camouflaged in late summer, when the leaves have mostly fallen. In habit D. transiens suggests D. filiformis, but differs in its pinnate, not quinque- or palmately trifoliolate foliage, in its proportionately wider because shorter leaflets, and in the free epistemonous petals, of which the inner pair never forms an united sheath around the anthers. From the coarse and common D. leporina, which has the same free keel-petals, it differs more directly in its frail stature, few leaflets, and few-flowered spikes of smaller flowers; and from the less similar D. polygonoides in (inter alia) the deciduous interfloral bracts and small calycine glands. To be sought elsewhere along the east foothills of Sierra Madre.

References: [Article] Barneby, Rupert C. 1977. Daleae Imagines, an illustrated revision of Errazurizia Philippi, Psorothamnus Rydberg, Marine Liebmann, and Dalea Lucanus emen. Barneby, including all species of Leguminosae tribe Amorpheae Borissova ever referred to Dalea. Mem. New York Bot. Gard. 27: 1-892.

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