115.  Dalea minutifolia (Rydberg) Harms

(Plate CV)

Slender but wiry, closely branching, erect or less often diffuse and straggling shrubs up to 1 m tall, the stramineous or purplish young stems densely verruculose, either glabrous to the inflorescence or the growing tips, or the leaf-stalks, or the leaflets, or some of these, thinly puberulent with short spreading hairs, the small but numerous (drought-deciduous) leaves green, the thick-textured leaflets smooth above, punctate and sometimes glaucescent beneath; leaf-spurs 0.3-0.6 mm long; stipules narrowly triangular or subulate, castaneous or livid, 0.8-1.8 mm long intrapetiolular glands 0; post-petiolular glands large, conic or mammiform; leaves (2) 3-9 (12) mm long, short-petioled, with 2-4 (5) crowded pairs of obovate, obovate-cuneate, or broadly oblanceolate, retuse or emarginate, mostly folded and backwardly arched leaflets 1-3 mm long; peduncles all or almost all terminal to leafy spurs or branchlets, mostly very short or obsolete, a few of the earliest up to 12 (25) mm long; spikes moderately dense, few-flowered, ovoid-conic becoming ovoid, subglobose, or shortly oblong, without petals or androecia 6-8.5 mm diam, the densely villosulous axis 2-15 (30) mm long; bracts promptly deciduous, ovate or lance-acuminate, firm, purplish or livid, prominently gland-pustulate, dorsally pilosulous or the lowest glabrous, glabrous within; calyx 3.1-4.4 (4.7) mm long, densely pilosulous with fine spreading hairs up to 0.4-0.8 mm long, the tube 2.1-2.7 mm long, a trifle recessed behind banner and the orifice oblique, the orange or castaneous, distally livid ribs becoming prominent, the intervals charged with 1 sometimes irregular row of ± 4-6 golden or orange glands, the deltate- or triangular-apiculate or -cuspidate, gland-spurred teeth somewhat unequal, the dorsal one 1-1.8 (2.2) mm long, ± 1/2-3/3 as long as tube; petals bicolored, the banner opening yellowish, rubescent, the epistemonous ones purple, perched well below middle of androecium, all charged with a large, linear-elliptic gland below the apex; banner 4-5.3 (6) mm long, the claw 1.5-2.6 (3) mm, the deltate-cordate blade 2.8-3.5 mm long, 3.2-4.8 mm wide, recessed at base into a shallow cornet; wings 4-6 mm long, the claw 0.8-1.6 mm, the broadly lance-oblong blades 3.4-4.8 mm long, 1.9-2.5 mm wide; heel 4.5-7.5 (8) mm long, the claws 1.3-2.8 (3) mm, the obliquely obovate blades 3.5-5 (5.4) mm long, 2.3-2.9 (3.4) mm wide; androecium 10-merous, 5.5-7.4 (8) mm long, the longer filaments free for 1.7-2.7 (3) mm, the connective gland-tipped, the anthers 0.5-0.75 mm long; pod (little known) in profile subdeltate, ±2.5 mm long, the style-base at corner, the filiform prow slightly convex, the valves hyaline in lower third, thence thinly papery, villosulous, and charged with a few large glands; seed ±1.8 mm long. — Collections: 30 (ii).

Plains and hillsides, especially in exposed or barren places, becoming locally dominant in actively degenerating badlands and on the pumice sands in the foothills of Orizaba, ± 2100-2800 m, Valley or Mexico and adjoining plateau, e. through Tlaxcala to centr. and n. Puebla and adjoining Veracruz, and n. through Hidalgo an unknown distance into San Luis Potosi. — Flowering July to January — Representative: San Luis Potosi: Schaffner 587/786 (M, MEXU, NY); Troll 541 (M). Hidalgo. Actopan: Bonpland 4112 (P-HBK, P, herb. Bonpl.). Huasca: Matuda 831

(MEXU). Atotonilco El Grande: Ripley & Barneby 13,623 (CAS, NY, US). Pachuca: Rose & Painter 8788 (NY). Mineral del Monte: Rzedowski 18,182 (ENCB). Tepeapulco: Rzedowski 18,281 (ENCB). Veracruz.: Purpus 11,164 (F); Mueller 513 (BR, NY). Puebla. Tlachichuca: Galeotti 3433 (G, BR). Cd. Serdan: Ripley & Barneby 14,744 (CAS, F, GH, MICH, MEXU, NY, UC, US). Esperanza: Balls 4456 (GH, K, US), 4507 (UC, US). : La Union near Puebla, Arsene 443 (GH, NY, US). Tlaxcala. : Tlaxco, Aguilar 8-A-11 (ENCB). Mexico (Edo). Huixquilucan: Rzedowski 21,957 (ENCB). Texcoco: Paray 1739 (ENCB). Mexico (D.F.): Rzedowski 546 (ENCB); Paray 1515 (ENCB).

Dalea minutifolia (Rydb.) Harms, Verhandl. Bot. Ver. Brandenb. 65: 88. 1923, based on Parosela minutifolia (with minute leaflets) Rydb., N. Amer. Fl. 24: 87. 1920.— "Type collected at Pachuca, Hidalgo, May, 1905, Purpus 1145..." — Holotypus, NY! isotypus, UC! — Parosela polycephala var. minutifolia (Rydb.) Macbr., Contrib. Gray Herb. New Ser. 65: 18. 1922.

Parosela polycephala (with many spikes) Rydb., N. Amer. Fl. 24: 90. 1920.— "Type collected in San Luis Potosi, 1878, Parry & Palmer 160..." — Holotypus, US (not seen); isotypi, K, NY, P! — Dalea polycephala (Rydb.) Bullock, Kew Bull. 1939: 197. 1939.

A wiry undershrub of modest proportions, notable for the extreme xerophytic reduction of the foliage accompanied by high development of secretory vesicles almost throughout the plant body, the stems and undersurface of the little fleshy, folded leaflets being densely verruculose and each petal charged with a large subapical blister-gland. The relatively loose and few-flowered spikes of short-toothed calyces subtended by early deciduous bracts suffice to distinguish D. minutifolia from the equally xerophytic and heavily warted D. hemsleyana. These two species are allopatric as far as known for certain, but exact localities for D. minutifolia in San Luis Potosi are lacking.

While uniform in general appearance, D. minutifolia like many kindred daleas occurs in glabrous and thinly pubescent variants, recognized by Rydberg as coordinate species. In 1920 however, the pubescent phase was known (to Rydberg) only from San Luis Potosi and the glabrous one from Hidalgo southward, suggesting a geographic correlation which does not exist in fact. In reality the pubescent form had been collected already by Humboldt and Bonpland at Actopan, only a short distance from the type-locality, at Pachuca, of supposedly glabrous D. minutifolia, of which even the type series includes puberulent individual plants. The puberulent variant is apparently the commoner of the two, and has been traced south to the limit of the species in Mexico and Distrito Federal. There is no longer any basis for maintaining two taxonomic categories, even at varietal level.

Here and there on the bleak pumice plains at the foot of Cofre de Perote and Orizaba the plants of D. minutifolia form extensive colonies, crowding together into sere thickets standing a foot or two tall, but becoming in the most exposed places depressed or trailing. In thin pine-juniper woodland near Perote occurs an ambiguous dalea (Ripley & Barneby 14,748, NY) that seems to combine features of D. minutifolia and D. versicolor var. lasiostachya. It might be described as a slender, unusually warty and small-leaved form of the latter, or as a form of D. minutifolia with enlarged leaves and exceptionally long-toothed, long-hairy calyx. No form of D. versicolor is known to occur near Perote, and the true nature of this interesting form remains to be determined.

The earliest known collection of D. minutifolia is preserved in the herbarium of Sesse & Mocino (No. 2667bis, F, MA), but cannot be connected successfully with any of the still unidentified names based on material dispersed out of the collection by Pavon.

A photograph of a Humboldt collection at Berlin, presumably a duplicate of those in Paris cited above, was distributed (Field Neg. 726) by Macbride as Dalea microphylla

B. K., a Peruvian dalea quite different in detail although similar in the diminutive foliage. Cf. D. carthagenensis var. brevis.