Dalea polystachya
Rupert C. Barneby
61. Dalea polystachya (Sesse & Mocino) Barneby
(Plate LXVII)
Herbaceous or feebly suffruticose, 8-18 dm tall, from a stout woody perennial root, glabrous to the inflorescence or (rarely) the base of the stems late in the dry season giving rise to gray-villous spurs bearing short leaves (leaflets 2-4 pairs), the flowering stems solitary in young plants but later 2-several, virgately erect and ascending, striate, eglandular or very sparsely microglandular, usually purplish, densely leafy (but the leaves drought-deciduous), passing upward into an openly few-branching, sparsely leafy panicle of spikes, the foliage green, the leaflets usually of rather thick texture, paler and punctate beneath; leaf-spurs small but prominent, up to 0.5 mm long; stipules subulate or triangular, 0.5-2.5 mm long, purplish and subglandular becoming dry and early deciduous; intrapetiolular glands 0; post-petiolular glands prominent, rounded, pale or orange; main cauline leaves 3-9(11) cm long, very shortly petioled or subsessile, with (8) 12- 20 ( 23) pairs of oblong to oblong-elliptic, obtuse, emarginate, or obtuse and bluntly gland-mucronulate, flat leaflets (1) 2-6 mm long; peduncles terminal to all branchlets of the panicle, 0.5-7.5 cm long, mostly appearing longer because of suppression of upper leaves; spikes oblong-ovoid, becoming ovoid to cylindroid, in fruit only moderately dense, without petals 8-12 (13) mm diam, the densely pilosulous axis becoming 1-5 (8) cm long; bracts deciduous, ovate to lance- acuminate or -caudate, 3-6 mm long, the median and upper ones scarious-margined at base, the tips livid, all pilosulous dorsally at base or throughout, gland-charged distally, glabrous within; calyx 4-5.6 mm long, sessile, densely pilose with weak, spiral hairs up to (0.8) 1-1.3 mm long, the tube 2.2-3 mm long, oblique at mouth but the dorsal sinus not strongly recessed, the ribs slender, livid, the membranous intervals sprinkled with many small, scattered, yellow glands, the triangular-aristate, gland-spurred teeth somewhat unequal, the dorsal one narrowest and longest, (1.3) 1.7-2.8 mm long, (1) 0.6 mm shorter to 0.4 mm longer than the tube; petals either bright blue or rose-purple, the banner with a pale, commonly gland-sprinkled, finally rubescent eye, the banner sometimes charged with a minute terminal gland, the keel- tip glandless, the inner petals elevated ± 1.6-2.4 mm from the hypanthium rim, the keel-blades united by their outer edges; banner 5-6.9 mm long, the claw 2.5-4.3 mm, the deltate-obcordate blade 2.7-3.7 mm long, 2.8-4 mm wide; wings 4.2-6.8 mm long, the claw 1.6-2.6 mm, the obliquely oblong-obovate or -ovate blade 2.7-4.2 mm long, 1.6-2.6 mm wide; keel 6-8.2 mm long, the claws 2.3-4.6 mm, the broadly obovate blades 3.6-5 mm long, 2-2.9 mm wide; androecium 10-merous, 6.5-7.8 mm long, the longest filament free for (1.5) 1.8-2.8 mm, the connective gland-tipped, the anthers 0.5-0.75 mm long; pod obliquely ovoid, 2.8-3 mm long, the style-base terminal but excentric, the valves hyaline at base, beyond the middle thinly papery, pilosulous, and minutely gland-sprinkled, the keels subfiliform. — Collections: 16 (iii).
Dry sunny hillsides in oak woodland and sometimes on cooler slopes of barrancas in either oak-brush or oak-pine woodland, 1530-2400 m, local and usually occurring in small numbers but widely distributed through the Transverse Volcanic Belt from s.-e. Estado de Mexico to w. Jalisco and adjoining Aguas Calientes, and along the Sierras Madre Occidental and Sur from central Durango and adjoining Sinaloa to Guerrero. — Flowering October to March. —Representative: Mexico: 7 mi NE of Temascaltepec, Gentry, Barclay & Arguelles 19,605 (RENNER, US); Tejupilco, Hinton 2720 (K, US); Valle de Bravo, Ripley & Barneby 14,892 (CAS, DAO, GH, MEXU, MICH, US). Michoacan: Cerro Azul near Morelia, Arsene 8457 (BR, F, US); 8 mi s. of Uruapan, Ripley & Barneby 14,098 (CAS, NY, US). Jalisco: Sierra del Halo, Koelz 34,142 (ENCB, MICH); Altenguillo to Jacala (typus of P. longifolia). Aguas Calientes: Sierra del Laurel near Cadrillo, Rzedowski 14,102 (ENCB, MICH). Durango: 5½ mi e- of El Salto, ± 55 mi w.-s.-w. of Ciudad Durango, Waterfall 13,619 (OKLA, US); Sierra Madre, perhaps in Sinaloa (typus of P. roseiflora). Guerrero: near Chilapa (typus). Oaxaca: Miahuatlan to San Andres, pacific slope, Liebmann 4608 (F, US).
Dalea polystachya (Sesse & Mocino) Barneby, comb. nov., based on Psoralea polystachya (with many spikes) S. & M., Fl. Nov. Hisp. 121. 1889 ("polistachia"). — "Habitat in Chilapae montibus [Guerrero]." —Lectotypus, labelled "Psoralea Polystachia N [obis]", herb. Sesse & Mocino No. 2656, MA! isotypus (fragm.), F!
Parosela lagopina (resembling a hare’s-foot, of the silky flower spikes) Rydb., N. Amer. Fl. 24: 72. 1920.-"Type collected at Chacala, Durango, March 7, 1899, Goldman 357..."—Holotypus, US! isotypi, GH, NY!—Dalea lagopina (Rydb.) Gentry, Madrono 10: 249. 1950.
Parosela roseiflora (pink-flowered) Rydb., N. Amer. Fl. 24: 105. 1920.— "Type collected in Sierra Madre (Sinaloa or Durango), Seemann..." — Holotypus, GH! isotypus, K! -Dalea roseiflora (Rydb.) Riley, Kew Bull. 1923: 337. 1923.
Parosela longifolia (long-leaved) Rydb., N. Amer. Fl. 24: 105. 1920.— "Type collected on the road from Altenguilla to Jacala, Jalisco, March 5, 1897, E. W. Nelson 4016..." — Holotypus, US! isotypus, NY!
Useful diagnostic characters of D. polystachya are the tall, virgate stems, striate but not or scarcely gland-verruculose, which arise anew each year from near soil-level or from a weakly developed caudex; the many (mostly 12-20 pairs of) flat oblong leaflets, quite glabrous except on rare basal offsets arising in late autumn or winter; and the moderately dense spikes of silvery-villous calyces subtended by deciduous, internally glabrous bracts. The species is widely dispersed through south and south-west Mexico, but seems not to be abundant anywhere; in each of three stations known to me only a few plants were found. The petals may be either bright blue or rose-purple, but the color-types are not geographically segregated and seem taxonomically insignificant. The purple form appears to predominate in the Sierras Madre Occidental and Sur, but has been found close to the blue form in southeast Mexico (cf. Gentry et al. 19,605, from n.-e. of Temascaltepec and Hinton 2720 from Tejupilco). Both occur in central Michoacan (near Morelia, purple, near Uruapan, vivid blue), and near the Sierra crest in western Durango. The species is partly sympatric with the related D. pectinata, but is easily separated by the broad and flat, not linear-elliptic and comblike leaflets. Differential characters of the more closely related D. nobilis and D. escobilla are discussed under these headings.
Of the modern synonyms cited above, P. roseiflora and P. longifolia were clearly based on minor variants of one species. Rydberg possessed only incomplete material of either, and with the passage of time the supposed differences (Rydberg, 1920, p. 71, in clave) involving relative length of bracts, calyx-tube, and teeth, have fallen into perspective as part of a variational range normal in Dalea. The case of P. lagopina is different. The typus of the latter consists of summit branchlets gathered in early March when the main flowering season was long past, the flower described by Rydberg being, I believe, only a tardy bud. The protologue pictures P. lagopina as a coarse annual related to Rydberg’s P. lagopus (= Dalea exserta of this paper), but nothing in the specimen supports this view of its relationship or duration. So far as can be seen, the foliage and inflorescence accord well enough with the present concept of D. polystachya, except that the main spikes (central, I suppose, to a panicle of several), is uncommonly long (reaching 8 cm) and the fruiting calyx is large, ± 7 mm long (tube 4.7-5 mm, teeth 1.7-2.1 mm) and becomes tumid and oblong-ellipsoid eventually (cf. Plate LXVII fig. 6c). Further, the vesture of the calyx is relatively short (hairs up 0.5 mm), and the androecium longer (± 11 mm) than seen elsewhere in genuine D. polystachya. No rational decision can be reached about the status of D. lagopina until more complete material becomes available. It may yet prove to be a distinct entity related not only to D. polystachya but also to D. nobilis (q.v.), of which it may conceivably prove to be a vegetatively glabrous variant.
See also a comment on Dalea hypoglottidea DC. in Appendix I.
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:
