Dalea leptostachya

Title

Dalea leptostachya

Author(s)

Rupert C. Barneby

Scientific Name

Dalea leptostachya DC.

Description

136.  Dalea leptostachya DeCandolle

(Plate CXIII)

Slender shrubs (0.7) 1-3 m tall, with 1-3 erect, mostly simple trunks up to 1.5 cm diam near base, freely and loosely branching distally, either glabrous (except for minutely ciliolate stipules) up to the inflorescence or some upper leaves villosulous marginally on both sides with fine short ascending hairs, the older stems purplish- brown becoming corky and furrowed, the young twigs greenish or purplish, sometimes glaucescent, sparsely verruculose, the foliage somewhat bicolored, the leaflets bright green or golden-green and visibly penninerved above, paler and punctate beneath; leaf-spurs 0.6-1.5 mm long; stipules narrowly triangular-subulate, 0.5-1 (1.5) mm long, livid; intrapetiolular glands 0; post-petiolular glands large, obtuse, not strongly emergent; leaves petioled, (2) 3-11 cm long, with subterete but narrowly margined rachis and 2-5 pairs of relatively large and distant, elliptic, rhombic-elliptic, or broadly oblanceolate, acute to short-acuminate, gland-tipped leaflets (5) 10-27 mm long, carinate dorsally, the margins charged with a row of close-set livid impressed glands, hence sometimes minutely crenulate; peduncles both leaf-opposed and terminal to branchlets, 1.5-6 (8.5) cm long; spikes long, lax, narrow, the flowers (pressed) falling into ± 2 series revealing the pilosulous axis, this becoming (1) 2.5-12 (15) cm long; bracts deciduous, ovate, short-acuminate, firm, navicular and keeled dorsally, 2.5-4.5 mm long, glandular and glabrous on back, ciliolate, glabrous within; calyx (sessile) 4.4-6.2 mm long, densely silky-pilosulous with yellowing hairs, the rather firm-textured tube 2.3-2.8 (3.5) mm long, the ribs thick, bluntly prominent, the intervals minutely impressed-glandular, the deltate- or triangular-acuminate or subaristate teeth unequal, the dorsal one longest, recurved in age, 1.9-2.8 (3.5) mm long, either longer or shorter than tube, the rest shorter and proportionately broader; petals greenish-yellow early fading brown or livid-purple, the banner and keel gland-tipped, the banner often also gland-sprinkled near its eye, the epistemonous ones perched much below middle of androecium (± 1-2 mm above hypanthium); banner subcarnose, (4) 4.6-6 mm long, the claw 1.7-2.3 mm long, the rhombic-ovate blade recurved through ± 20°, (2) 2.6-3.6 mm long, 2.4-3.2 mm wide, hooded and at base recessed into a shallow cornet opening adaxially; wings 4-6.4 mm long, the claw 1.1-1.7 mm, the ovate- or lance- oblong blade 2.8-5 mm long, 1.5-2.4 mm wide; keel (5.8) 6-7.7 mm long, the claws (1.6) 2-2.7 mm, the broadly ovate-obovate blades (3.8) 4-5.4 mm long, 2.2-3.1 mm wide; androecium 10-merous, 6.2-7.6 mm long, the longer filaments free for 2.2-2.7 mm, the connective gland-tipped, the anthers 0.75-0.9 mm long; pod in profile triangular, moderately compressed, 3.2-4.5 mm long, the latero-terminal style-base up to 1.3 mm long, the prow ± dilated, 0.5 mm wide, the valves hyaline in lower 1/2-2/3, thence greenish, softly pilosulous, and charged with a few small glands; seed 2.3-2.9 mm long; 2n = 14 (Mosquin). — Collections: 37 (v).

Dry rocky and brushy hillsides, commonly but not exclusively on limestone, mostly between 700 and 1650 m (2100-5500 ft), locally plentiful around the periphery of the e. lobe of Balsas Depression, from e. Michoacan (mpos Jungapeo and Huetamo) and s.-w. Mexico (mpo Temascaltepec) through Morelos into s.-w. Puebla (mpos Izucar de Matamoros and Patlalcingo), s. to the n. slope of Sierra Madre del Sur in Guerrero; reported from the Pacific Coast in Guerrero (near Acapulco) and on questionable evidence from n. Michoacan (Morelia). — Flowering September to February.—Representative: MichoacAn: Hinton 6968 (ARIZ, F, NY, UC, US, Z); Paray 1758 (ENCB). Mexico: Hinton 5184 (ARIZ, F, US), 5292 (F, US, W). Morelos: Berlandier 1073 (OXF); Pringle 11,287 (F, MEXU, NY, US, Z), 11,416 (ARIZ, F, OKLA, UC, US); Ripley & Barneby 13,696 (CAS, NY, US). Guerrero: Pringle 8410 (F, L, M, MEXU, MICH, NY, UC, US, Z); Rzedowski 23,525 (ENCB, MICH); Feddema 2776 (MICH); Paray 1859 (ENCB).

Dalea leptostachya (with lean spikes) DC., Prod. 2: 246. 1825.— "...in America calid."—Holotypus, "ex herb. Thibaud., 1815", G-DC!

Dalea ovalifolia (with oval leaflets) G. Don, Gen. Hist. Diehl. Pl. 2: 226. 1832.— "Native of Mexico...(v.s. in herb. Lamb.)." —Holotypus, labelled "D. ovalifolia sp. nov. de Mexico", OXF! isotypi, G ("D. ovalifolia, N[ueva] E[spana]"); Herb. Sesse & Mocino 2670, MA,F (fragm)!

Parosela acutifolia sensu Rydb., N. Amer. Fl. 24: 86. 1920; non Dalea acutifolia DC.

An unmistakable dalea, amply characterized by the syndrome of leaves large for the genus, composed of 5-11 acute to shortly acuminate leaflets mostly over 1 cm long, and loose, flexible spikes of dull yellow flowers. The mature plant assumes the form of a slender treelet, with one or few crooked simple trunks dividing distally into an irregularly doming head of pliant, thinly leafy branchlets. Rydberg (1920, pp. 85, 86, under the misplaced name Parosela acutifolia) described D. leptostachya as glabrous up to the silky-pilose calyces, but this is only sometimes accurate, the foliage and young twigs, especially distally, varying from truly hairless to gray-silky, sometimes (cf. Ripley & Barneby 13,696, cited supra) in individuals growing side by side.

With two exceptions all known specimens of D. leptostachya originated from within the eastern lobe of the Balsas Depression, and this is certainly its focus of abundance. It was not collected by early botanists at Acapulco, but was encountered there recently (Paray 1859, cited supra); its status as an aboriginal native along the south slope of the Pacific Cordillera requires confirmation. The same is needed in the case of an unnumbered unicate attributed to Arsene (in 1910, F), supposedly from near Morelia de Michoacan, but under suspicion as one of the pirated exsiccata distributed under this label.