Dalea bicolor var. naviculifolia
Rupert C. Barneby
108d. Dalea bicolor Humboldt & Bonpland ex Willdenow var. naviculifolia (Hemsley) Barneby
(Plate CII)
Small shrubs, depressed and trailing or erect and freely branching, up to 7 dm tall but mostly less; leaves 6-26 mm long; leaflets (4) 5-9 (10) pairs, oblong-elliptic to oblanceolate or narrowly obovate navicular or loosely folded, obtuse but gland- mucronulate, 1.5-4 (4.5) mm long, green or ashen, either glabrous or thinly pubescent above; spikes loose or moderately dense, in outline narrowly lanceolate to linear- oblong, without petals 4.5-6 mm diam, the axis becoming (1) 1.5-6 (9) cm long; bracts ovate-acuminate, 1-1.7 mm long; calyx 2.5-3.2 mm long, the tube 1.6-2.3 mm, either glabrous below the teeth, puberulent from middle upward, or puberulent throughout, the teeth ovate or triangular, the dorsal one 0.5-1 mm long; petals of var. bicolor but small, the keel-blades mostly 3.6-4.6, rarely 5 mm long. — Collections: 9 (iii).
Cool exposures of steep mountainsides and grassy glades in pine-oak woodland, 1935-2250 m (6450-7500 ft), locally abundant but apparently confined to the Mixteca Alta, especially on headwaters of Rio Tomellin, n.-centr. Oaxaca. — Flowering September to January. —Material: MEXICO, s.l., Karwinski in 1827 (M). Oaxaca. Asuncion Nochixtlan: Ripley & Barneby 14,590 (CAS, MICH, NY, UC, US), 14,597 (NY); Seler 1522 (US). Nazareno Etla: Conzatti 4206 (MEXU); Pringle 6017 (BR, ENCB, F, GH, K, M, MEXU, NY, SD, UC, US, W); L. C. Smith 886 (GH); Ripley & Barneby 14,666 (CAS, DAO, MEXU, US).
Dalea bicolor H. & B. ex Willd. var. naviculifolia (Hemsl.) Barneby, stat. nov., based on D. naviculifolia (with boat-shaped leaflets) Hemsl., Diag. Pl. Nov. 7. 1878. — "Mexico: Bates, sine loco..." — Holotypus, K! —Parosela naviculifolia (Hemsl.) Rose, Contrib. U. S. Nat. Herb. 10: 104. 1906.
The typus of D. naviculifolia is notable for a combination of extreme characters none of which, however, is wholly foreign to var. bicolor. It follows that a description of var. bicolor wide enough to encompass all its known variants very nearly encompasses D. naviculifolia. The small flower associated with the epithet naviculifolia is nearly matched for size in some specimens of var. bicolor in which the calyx is silky-pilosulous and combined with relatively few and large leaflets. A glabrescent calyx, which Rydberg (1920, p. 69) stressed as a differential character of Parosela naviculifolia is sometimes found in var. bicolor, but there associated with a larger flower and leaflets larger but either few or many. Until recently the range of var. naviculifolia seemed to lie safely beyond the orbit of var. bicolor, but this supposed allopatry has proved illusory. Typical var. bicolor has been traced south into Mixteca Alta near Nochixtlan (Ripley & Barneby 13,671) and occurs on limestone hills at the north end of the valley of Oaxaca, within a few kilometers of typical var. naviculifolia, although this occupies a cooler habitat at greater elevations. Plants from the last named locality (Ripley & Barneby 14,670) have flowers hardly larger than that of var. naviculifolia, but leaflets not over six pairs and a densely villous calyx. It appears that var. naviculifolia represents a dwarf montane race of D. bicolor in which several variable characters coincide at or close to the limit of variation within the species sens. lat.
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:
