Vachellia villaregalis (McVaugh) Seigler & Ebinger, Phytologia 87:  169.  2005.
syn.  Acacia villaregalis McVaugh, Flora Novo-Galiciana 5:  141.  1983.

Synonymy and types

Basionym:  Acacia villaregalis McVaugh, Flora Novo-Galiciana  5: 141.  1983. - TYPE:  MEXICO.  JALISCO:  Cima Cerro de Tequila, bosque de Quercus spp. y Pinus spp., alt. 2850 m, 17 Mar 1974, L. M. Villarreal 6171 (holotype:  MICH; isotype: IBUG).

Formal description

Spreading shrub 0.7-1.5 m tall.  Bark dark gray to dark reddish brown, smooth.  Twigs dark brown to reddish brown, slightly flexuous, usually glabrous.  Short shoots absent, or very short and not well developed.  Leaves alternate, 50-95 mm long.  Stipular spines reddish brown to purplish, becoming gray with age, symmetrical, terete to oval, straight, stout, to 20 x 1-2 mm near the base, glabrousPetiole adaxially shallowly grooved, 5-13 mm long, glabrous or nearly so; petiolar gland solitary, located medially to just below the lower pinna pair, sessile, circular to elongated, 0.3-1.3 mm across, apex depressed, glabrousRachis adaxially shallowly grooved, 40-90 mm long, glabrous, a sessile, circular gland 0.3-0.5 mm across between the upper 1 to 3 pinna pairs.  Pinnae (5-) 8-12 pairs per leaf, 16-26 mm long, 3-6 mm between pinna pairs.  Petiolules 0.3-0.7 mm long.  Leaflets 19 to 31 pairs per pinna, opposite, 0.5-0.9 mm between leaflets,  linear, 3.1-4.8 x 0.5-0.8 mm, glabrous, lateral veins not obvious, only one vein from the base, base oblique, margins usually ciliate near the base, apex acuteInflorescence a densely flowered globose head, 5-7 mm across, solitary or in clusters of 2 to 6 in the leaf axil.  Peduncles 6-20 x 0.2-0.4 mm, glabrousInvolucre bracts 4 to 6, located at the base of the globose head, glabrous, persistent.  Floral bracts spatulate, 0.8-1.4 mm long, glabrous, deciduous.  Flowers sessile, bright yellow; calyx 5-lobed, 0.8-1.3 mm long, glabrous; corolla 5-lobed, 1.6-2.3 mm long, glabrous, the lobes sometimes lightly puberulent; stamen filaments 2.5-3.5 mm long, weakly coherent for about half their length; ovary glabrous, sessile or on a stipe to 0.2 mm long.  Legume dark reddish brown, straight, flat in cross section, not constricted between the seeds, linear-oblong, 40-70 x 8-12 mm, coriaceous, reticulately striate, glabrous, eglandular, dehiscent along both sutures; stipe to 12 mm long; apex acute to obtuse.  Seeds uniseriate, no pulp, brown, oblong to elliptic to oval, flattened, 5.0-7.1 x 3.6-5.3 mm, smooth; pleurogram U-shaped to nearly oval, 2.5-4.0 mm across.  Flowers in March to May. Chromosome number not determined.


Mountainsides, forest clearings, pastures, and rocky ravines in shaded oak and oak-pine forests between 1500-2850 m elevation in Jalisco and Nayarit, Mexico.  As far as can be determined this species is endemic to the mountains in and near the basin of the Río Santiago (McVaugh 1983).

Additional info

Vachellia villaregalis appears to be a narrow endemic restricted to the states of Jalisco and Nayarit, Mexico.  Presently we have seen only three specimens.  These specimens were all similar, and very little variation was found.  Floral and vegetative characteristics place this species very close to V. macracantha, and in the broad sense could be considered a part of that species.  However, the small stature of V. villaregalis individuals (spreading shrub to 1.5 m tall), along with smaller leaves that have mostly less than 12 pinna pairs can be used for consistent separation.  Of the three specimens of Vachellia villaregalis tested, one was strongly positive for cyanide.

McVaugh (1983) suggested that Vachellia villaregalis is very similar to V. macracantha, but in Nueva Galicia the latter species so-called is a plant of the Pacific lowlands, with somewhat larger flower-heads and larger flowers, the calyx - and corolla-teeth tufted on the backs.  McVaugh (1983) also observed that the stamens of V. villaregalis, about 75 in number, are apparently always somewhat coherent at the base, but are readily separable and the identity of individual filaments is not lost.  All of the material we observed had these slightly coherent filaments for about half their length.  This cohesion is very weak, and it is possible that the fusion is the result of high nectar loads.

Flowering time


Representative specimens