Astragalus guatemalensis var. brevidentatus

Title

Astragalus guatemalensis var. brevidentatus

Authors

Rupert C. Barneby

Scientific Name

Astragalus guatemalensis var. brevidentatus (Hemsl.) Barneby

Description

11b. Astragalus guatemalensis var. brevidentatus

Like var. guatemalensis in growth-habit, the stems 3-15 (24) dm. long; leaflets (13) 17-25; racemes shortly but more loosely 6-20 (30)-flowered, or those of terminal branchlets only 2—5-flowered. the axis (0.5) 1.5-3.5 (5) cm. long in fruit; calyx strigulose with black, rarely white hairs up to ± 0.2-0.3 mm. long, the tube 2.6-3.6 mm. long, 2.2-3 mm. in diameter, the triangular-subulate, broadly deltoid, or more elongate and then truly subulate teeth 0.6-2.5 mm. long; petals commonly pink-purple, rarely yellowish; banner 9-11.3 mm. long; stipe of the pod 1.5-2.5 mm., the body 12-21 mm. long, (4) 5-7 (8) mm. in diameter, glabrous or minutely black-strigulose; ovules (11) 12-18 (19).—Collections: 24 (iii); representative: Hinton 12,917 (NY, TEX, US), 5232 (K, NY, US), 8912 (MICH, NY); Matuda 18, 841 (MICH, NY); Lyonnet 703 (NY, US); McVaugh 13,457 (K, MICH), 14,382 (K, MICH); Ripley & Barneby 13,405 (NY, RSA).

Brushy hillsides, open woodland, and shaded glens in mixed pine and oak forest, (5500) 6000-8500 feet, apparently not uncommon in the mountains of southcentral Mexico, from Mexico State to Michoacan and western Jalisco, south to Oaxaca.—Map No. 7.—May to January.

Astragalus guatemalensis var. brevidentatus (Hemsl.), comb. nov., based on A. strigulosus var. brevidentatus (short-toothed, of the calyx) Hemsl., Biol. Centr.-Amer., Bot. 1: 266. 1880.—"Mexico, (Barker). Cultivated specimens only in Hb. Kew."—Holotypus, cult, in hort. Kew. Aug. 13, 1838, K!

Phaca elongata (lengthy) Mart. & Gal. in Bull. Acad. Roy. Brux. 10²: 51. 1843 (non A. elongatus Willd., 1803).—"... sur les montagnes calcaires de Sola et sur les rochers gneissiques de Yolotepeque, dans la cordillere, au sud d’Oaxaca, de 7 a 8000 pieds."—Holotypus, not examined; isotypi, Galeotti 3174, from "montagnes pres l’Ocean Pacifique a 8000'," K, P (2 sheets)!

Astragalus guatemalensis var. oaxacanus (of Oaxaca) Jones, Rev. Astrag. 189, Pl. 43. 1923—"This is Pringle’s No. 6264 from Oaxaca."—Holotypus, collected in the Sierra de San Felipe, Oaxaca, December 10, 1895, US! isotypi, CAS, DAV, G, GH, K, ND, NY, P, PH!— Atelophragma oaxacanum (Jones) Rydb. in Bull. Torr. Club 55: 160. 1928. Astragalus oaxacanus Rose ex Jones, l.c., nom. nud.

Astragalus Painteri (Joseph Hannum Painter, 1879-1908, clerk at Smithsonian Institution, assisted J. N. Rose in Mexico) Rose ex Jones, Rev. Astrag. 190, Pl. 43. 1923.—"Sierra de Ajusco, Morales [i.e., Morelos], Mexico, May 26, 1898 ... Pringle’s No. 6861 ... "—Holotypus, US! isotypi, GH, NY, POM!—Atelophragma Painteri (Rose) Rydb. in Bull. Torr. Club 55: 156. 1928.

The Oaxaca milk-vetch, var. brevidentatus, is the commonest and most widely dispersed in southcentral Mexico of the large-flowered Strigulosi. Similar to var. guatemalensis in the diffuse vinelike habit of growth and in nearly all technical characters other than the shorttoothed, more thinly appressed-pubescent calyx, it is geographically separated from it by the dip in the main Cordillera corresponding with the Isthmus of Tehuantepec. The variety is so circumscribed in these pages as to include a number of minor variants; it could perhaps be divided profitably into two coordinate races corresponding with Jones’s var. oaxacanus and A. Painteri. In the mountains lying between the valleys of Mexico and Cuernavaca the calyx-teeth are consistently very short, scarcely surpassing 1 mm. in length, and vary from broadly subulate to broadly deltoid, the typi of A. Painteri and var. brevidentatus being of the latter sort. To the west and south of this area the calyx-teeth become longer and narrower, varying from broadly subulate to exactly subulate, and from 1 mm. up to 2.5 mm. in length; however there seem to be no other differences correlated with the calyx-variants. The pod of the Oaxaca milk-vetch is most commonly glabrous, but a number of collections with minutely black- strigulose fruits are on record: several from Michoacan (Frye & Frye 3105; Hinton 15,465, both US; Ripley & Barneby 13,432, both CAS, NY, RSA) one from Guerrero (Hinton 14899, MICH, NY, UC); one from Oaxaca (the typus of var. oaxacanus); and the original plant from which var. brevidentatus was described. These pubescent-ovaried plants are interpreted as individual variants of no taxonomic importance. The petals of var. brevidentatus are normally pinkish-purple, but they fade rapidly in the herbarium, often appearing ochroleucous after a few years; and ochroleucous or "pale yellow" flowers have been seen and reported in field notes (Hinton 15,465, US) as well as the commoner purple.