Monographs Details: Dalea mixteca Barneby
Authors:Rupert C. Barneby
Authority: 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.
Scientific Name:Dalea mixteca Barneby
Description:Species Description - Slender wiry annuals from a yellow root, the primary axis erect but early inhibited, giving rise near base to several prostrately radiating, simple or irregularly few-branched stems up to (0.3) 1.5-4 dm long, these all smooth or remotely minutely glandular, thinly pilosulous with scattered weak sinuous ± spreading hairs up to 0.3-0.7 mm long, the foliage green or purplish, the leaflets glabrous both sides, ciliolate, smooth above, punctate beneath; leaf-spurs 0.5-1.2 mm long; stipules linear-subulate, ciliolate, 0.7-2.7 mm long; intrapetiolular glands minute; post-petiolular glands small but emergent; leaves mostly deciduous by late anthesis (hence little known), 1-1.5 cm long, shortly petioled, with margined rachis and (1) 2-3 (4) pairs of obovate ot obovate-cuneate, mostly emarginate, flat or weakly folded leaflets, the terminal one (usually elevated beyond the last pair) largest, up to 2.5-5.5 mm long; peduncles 0.5-3 cm long, the first of each stem appearing leaf-opposed, the rest terminal to branchlets; spikes loosely (5) 8-30 (35)-flowered, the flowers 2-ranked when pressed, not contiguous, the glabrous, flexuous axis becoming (0.5) 1-3 (3.5) cm long; bracts persistent, glabrous within and without, 2.4-4.2 mm long, the obovate boat-shaped body 2.2-3.4 mm long, embracing the calyx and in profile 1-1.4 mm wide, thinly herbaceous distally, scarious-margined, gland-sprinkled dorsally, abruptly contracted into a firm subulate involute tail 0.3-1 mm long; calyx 2.5 mm long, glabrous except for the silvery-ciliolate orifice, the tube 1.7-2 mm long, its ribs filiform, livid, the intervals scarious lustrous charged with 1 row of 3-4 minute fuscous glands, the broadly low-deltate teeth slightly unequal, the dorsal one longest and a little narrower than the rest, 0.5-0.8 mm long; petals at first bicolored, the banner greenish-white but early rubescent, the epistemonous petals dull wine-purple, perched 1.6-2.2 mm above hypanthium, all eglandular or the keel minutely gland-tipped; banner ± 3 mm long, the claw 1.6-1.7 mm, the deltate-cordate subacute hooded blade 1.5-2.7 mm long, 1.6-2.1 mm wide; wings 1.6 mm, the claw 0.3 mm, the oblong-elliptic blade 1.5 mm long, 0.8 mm wide; keel 1.8-2.3 mm long, the claws 0.4 mm, the blades 1.6-2 mm long, 1.2-1.6 mm wide; androecium 10-merous, 3.2-3.6 mm long, the longer filaments livid distally, free for 0.6-0.8 mm, the connective minutely gland-tipped, the anthers 0.3 mm long; pod triangular in profile, 2-2.4 mm long, the style at one corner, the glabrous valves hyaline in lower thence papery, purple or livid, minutely gland-sprinkled; seed olivaceous, 1.6-1.8 mm long; 2n = 14 (Mosquin). — Collections: 1 (i).

Distribution and Ecology - Dry rocky hillsides, on limestone, 1980 m (6600 ft), known only from the headwaters of Rio Mixteco, in mpo Teposcolula, Oaxaca. — Flowering October-November.

Latin Diagnosis - Dalea mixteca (of the Mixtec Indians) Barneby, sp. nov., D. obovatifoliae Ort. prae-sertim var. unciferae (S. & C.) Barneby affinis, floribus minimis secus axin glabrum laxe spicatis, carinae laminis 1.6-2 (nec ± 3-5) mm longis, necnon androecio abbreviato ± 3.5 (nec 5.5 et ultra) mm longo absimilis. - Oaxaca: arid limestone hills, associated with D. caeciliae Harms, San Juan Teposcolula, nov 6, 1966, Ripley & Barneby 14,688.


(Plate LXXV)

This is an inconspicuous little dalea, with wiry stems pressed to the ground, drought- deciduous foliage, and tiny flowers, the inner petals dark plum-purple, almost black. The species is related to D. obovatifolia, especially its relatively small-flowered, monocarpic var. uncifera, and perhaps derived from it. Calyces of D. mixteca and var. uncifera are essentially similar, but the latter differs in its longer petals and androecium, its spike pilosulous between flowers that stand close together, separated only by long-tailed bracts, in several vertical ranks.

Distribution:Oaxaca Mexico North America| Mexico North America|

Narratives:Dalea mixteca