Dalea lutea var. arsenei
Rupert C. Barneby
130b. Dalea lutea (Cavanilles) Willdenow var. arsenei (Macbride) Barneby
Apparently shrubby, but stature unknown; steins and nigrescent foliage either glabrous or thinly hirsute with weak spreading hairs up to ± 1.4 nun long; primary cauline leaves up to 4.5-7 cm long, with 9-15 (16) pairs of leaflets; spikes 2.5-10 cm long; calyx thinly pilose distally, the gland in the intercostal membranes 3-5, small, not very prominent; flowers large, the calyx 5.7-6.5 mm, its tube 2.8-3 mm, the dorsal tooth 2.7-3.7 mm long; banner 7-7.3 mm long; wings 7.2-7.5 mm long; keel 10-11 mm long, the claws 3.6-4 mm, the blades 13-1.1 mm long, 4-4.3 mm wide; androecium 10-11 mm long. — Collections: 3 (o).
Habitat not recorded, but to be sought in the oak-pine belt at ± 1650-1950 m (5500-6500 ft), known only from two disconnected regions in s. Mexico: mountains e. of Morelia, e. Michoacan; and on n. slope of Sierra Madre del Sur in e.-centr. Guerrero. — Flowering August to January. —Material: MichoacAn: route de Mexico, pres Morelia, Arsene 5696 (US). Guerrero: Ayotsinapa to Petatlan, E. W. Nelson 2147 (NY).
Dalea lutea (Cav.) Willd. var. arsenei (Macbr.) Barneby, stat. nov., based on Parosela arsenei (Arsene Gustave Joseph Brouard, Bro. Gerfroy Arsene, F.S.C., 1867-1938) Macbride, Contrib. Gray Herb., New Ser. 65: 21. 1922. — "Mexico: vicinity of Morelia, Michoacan, Arsene 5596..." — Holotypus, from "nord du Zapote, 1950 m., aout 4, 1910", GH! isotypus, US!
The existence in the Transverse Volcanic Belt of eastern Michoacan, close to populations of characteristic var. gigantea, of a second, genetically independent race of D. lutea is hardly credible unless the type-locality is at the edge of a more continuous range connecting it, perhaps through Sierra Madre del Sur, with the one other known locality in Guerrero. For the present it seems impossible to assimilate the three collections cited into var. gigantea, of which all other Mexican collections have at once fewer leaflets, densely shaggy-pilosulous young stems, and substantially smaller flowers.
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.