Dalea virgata
Rupert C. Barneby
69. Dalea virgata Lagasca
(Plate LXXII)
Robust suffruticose perennial herbs up to ± 1 m tall, the numerous virgate steins erect and ascending from an ultimately indurated base, effusely paniculate and only sparsely leafy distally, with spikes terminating all the branchlets, the stems below the middle striate, purplish, smooth, glabrous or obscurely puberulent, upward becoming thinly pilosulous or villosulous and at least sparsely verruculose, the young twigs and leaves puberulent to villosulous with short, curly or contorted hairs up to 0.1-0.4 mm long, the foliage green, the leaflets either glabrous or pubescent above, densely gland- speckled beneath; leaf-spurs 0.5-1 mm long; stipules linear-subulate or subsetiform, livid, becoming fragile and caducous, 0.5-4 mm long, glabrous, or minutely puberulent to thinly pilosulous; intrapetiolular glands 2, conic; post-petiolular glands prominent, mammiform or prickle-shaped; main cauline leaves 2.5-7 cm long, shortly petioled, with very narrowly margined, sparsely punctate rachis and 10-17 pairs of elliptic, bluntly gland-mucronate, dorsally carinate leaflets 4-10 mm long, either flat with elevated margins or shallowly cymbiform but not folded, the terminal leaflet sessile, usually a trifle shorter than the last pair, the leaves accompanying inflorescences smaller, with fewer (4-8 pairs of) shorter leaflets; peduncles 0-5.5 cm long; spikes dense but not conelike, ovoid becoming oblong-cylindroid, without petals ± 1 cm diam, the densely pilosulous axis becoming (0.5) 1-4 cm long; bracts deciduous, lance-acuminate or -caudate, boat-shaped, 3-5 mm long, livid and gross-glandular dorsally above the submembranous base, the lowest either glabrous or puberulent, the rest dorsally pilosulous at base or up to the middle, thence glabrate, all densely sericeous within; calyx 4.6-5.5 mm long, densely but shortly silky-pilosulous, the pallid, finally brownish tube ovoid, 2.6-3.3 mm long, faintly ribbed, the membranous intervals charged with small, scattered, transparent or yellowish glands, the triangular- to lance- acuminate teeth unequal, the dorsal one longest, 1.4-2.3 mm long, the rest shorter and broader, all minutely gland-spurred, the oblique orifice a little recessed behind the banner; petals lilac-purple or violet, the pale-eyed banner usually gland-tipped, the keel and wings elevated 1-2 mm above the hypanthium rim, the keel-blades united by their margins; banner 6.4-7.9 mm long, the claw 3-3.8 mm, the quadrately ovate- cordate blade 3.5-4.6 mm long, 3.6-5.2 mm wide; wings 6.2-7.9 mm long, the claw 2.2-2.9 mm, the oblong-elliptic or -oval blade 4.2-5.5 mm long, 1.5-2 mm wide; keel 8.3-11 mm long, the claws 3-4.5 mm, the broadly oval-obovate blades 5.7-7 mm long, 2.6-3.1 mm wide; androecium 10-merous, 8-9.8 mm long, the longest filament free for 2-2.8 mm, the anthers gland-tipped, 0.5-0.6 mm long; ovary thinly pilosulous and minutely glandular near apex, otherwise glabrous. — Collections: 9 (ii).
Open places on brushy hillsides in the oak-belt and ascending into thin pine-forest, 1950-2250 m (± 6500-7250 ft), local but forming colonies, known only from central Oaxaca (Sierra de San Felipe; Cordillera de Yavezia; Mixteca Alta).— Flowering October to February. —Representative: Oaxaca: Cordillera de Yavezia, Galeotti 3153 (BR, W); Sierra de San Felipe, type-collections of Parosela oaxacana and P. smithii, Ripley & Barneby 14,613 (NY), Conzatti 4061 (MEXU); 22 mi s.-e. of Nochixtlan, Ripley & Barneby 14,592 (CAS, F, GH, MEXU, MICH, NY, UC, US).
Dalea virgata Lag., Gen. & Sp. Nov. 23. 1816. — "Habitat in Imperio Mexicensi. In Hort. Reg. Matrit...." — No typus examined, but a cultivated specimen preserved at MA seen in form of Field Negative 29,414, F!
(?) Dalea pyramidalis Schlechtd., Linnaea 12: 292. 1838.— "In terris Mexicanis (Hegewisch hb. Lehm. et Bueck)." — Holotypus, presumably at HAL (herb. Schlechtd.), not seen, but the detailed description suggests no other species. So interpreted by Mart. & Gal., Bull. Acad. Brux. 10(2): 43. 1843.
Parosela oaxacana (of Oaxaca) Rose, Contrib. U. S. Nat. Herb. 10: 104. 1910.— "Type ...collected by Dr. C. G. Pringle on the Sierra de San Felipe, Oaxaca, 2250 meters, October 10, 1894 (no. 4961)." —Holotypus, US! isotypi, GH, M, MEXU, NY, UC, W, Z!—Dalea oaxacana (Rose) Bullock, Kew Bull. 1939: 197. 1939.
Parosela smithii (Charles Leonard Smith, 1866- ) Rydb., N. Amer. FL 24: 106. 1920. — "Type collected in Sierra de San Felipe, Oaxaca, November 19, 1894, Charles L. Smith 343.." — Holotypus, US! isotypi, F, NY, UC, and apparently, misnumbered 345, MEXU!
Parosela conzattii (Cassiano Conzatti, 1862-1951) Rydb. N. Amer. Fl. 24: 89. 1920.—"Type collected at Cerro San Antonio, Oaxaca, December 15, 1901, Conzatti..." — Holotypus, US! clastotypus (fragm), NY! —The specimen from Las Huertas, MEXU, labelled Conzatti 4061, is perhaps an isotypus!
At the height of its flowering season, in the sere months of late fall and early winter, D. virgata is among the handsomest shrubby daleas found in Mexico. The mature plant forms a sturdy bush about a meter high and through, formed of a multitude of virgate stems, at first simple and densely leafy, but branching distally into an ample, corymbose panicle of heads. In its small known range D. virgata is associated with two shrubby congeners, D. versicolor var. versicolor and D. bicolor var. naviculifolia. In both of these the leaflets are normally fewer, only exceptionally in excess of ten (as opposed to 10-17) pairs, and the flowers when young are distinctly bicolored, with banner at first white or yellowish in contrast to the purple keel. The calyx of var. versicolor has long (mostly 2.5-4, not 1.4-2.3 mm), plumose teeth; that of var. naviculifolia broadly ovate, minutely puberulent teeth less than 1 mm long. From D. polystachya, a related species not known to be sympatric but present in Sierra Madre del Sur not far distant, D. virgata differs (inter alia) by its larger flowers subtended by bracts silky (not glabrous) on the inner side.
The number of synonyms listed above suggests a highly variable species, but this is hardly so. The mature leaves vary from subglabrous to obviously pubescent, but the young foliage, at least high on the stems, is never wholly hairless. The calyx-teeth (especially the ventral pair) vary somewhat in length, but the dorsal one never, as far as now known, exceeds the tube. The stems, always charged with glands, might sometimes be described at tuberculate and sometimes not, the glands becoming, I suspect, more prominent as the stems age. These variations show no obvious correlation and do not affect materially the essentially uniform aspect of the plants. Rydberg referred specimens of D. virgata to three species of different sections in Parosela: Lasiostachyae (P. smithii, supposedly glabrous), Tuberculatae (P. conzattii), and Versicolores (P. oaxacana). Reassembled, the type- collections of these three segregates do illustrate a certain range of difference, but at the same time are closely similiar in habit, foliage, and detail of the flower.
During preliminary studies I have annotated and distributed all material of D. virgata as D. oaxacana (Rose) Bullock, the name under which I first learned to know the species. Here, with some misgiving, I take up the much earlier but poorly documented name D. virgata. Lagasca described D. virgata from plants grown in the Madrid Botanical Garden from seed known to be from Mexico, very likely sent home by Sesse or Maldonado. During my visit to the Madred herbarium I was unable to find any material so named, and as the protologue is too short and too generalized to provide a definite identification of the species, I had determined to discard it as an insoluble puzzle. Subsequently, however, I have seen the Field Museum photograph of an old specimen at MA which is labelled D. virgata and certainly represents the species here discussed. There is nothing in Lagasca’s description which would exclude D. oaxacana, and it seems safe to assume that the Madrid
Dalea virgata Lag., Gen. & Sp. Nov. 23. 1816. — "Habitat in Imperio Mexicensi. In Hort. Reg. Matrit...." — No typus examined, but a cultivated specimen preserved at MA seen in form of Field Negative 29,414, F! specimen, if not actually a typus, is authentic for the species grown there under Lagasca’s name. The name D. pyramidalis Schlechtd. is also referred here with some doubt, although for different reasons. No typus has been seen, but the long and exceptionally detailed description fits D. virgata precisely and suggests no other known Dalea. Schlechtendahl knew D. pyramidalis only as Mexican, preserved without more exact locality-data in the herbaria of Bueck and Lehmann. It may be worth noting that D. hegewischiana Steud., originally described by Schlechtendahl from specimens of the same provenance, is found today in the vale of Oaxaca, flowering at the same season as D. virgata. I have found no reference in the literature to the botanical itinerary of Hegewisch in Mexico.
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.Multimedia:
