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Vachellia brandegeana - leaves

Vachellia brandegeana - habit

Vachellia brandegeana - spines

Vachellia brandegeana - spines

Vachellia brandegeana - leaves

Name

Vachellia brandegeana (I. M. Johnston) Seigler & Ebinger, Phytologia 87:  146.  2005.
syn. Acacia brandegeana I. M. Johnston, Contr. Gray Herb.  75:  27.  1925.

Synonymy and types

Basionym:  Acacia brandegeana I. M. Johnst., Contr. Gray Herb.  75: 27. 1925.  Acaciopsis brandegeana (I. M. Johnst.) Britton & Rose, N. Amer. Fl.  23: 94.  1928. - TYPE:  MEXICO.  BAJA CALIFORNIA SUR:  Agua Verde Bay, 26 May 1921, I. M. Johnston 3881 (holotype GH; isotypes:  A, F, MO, NY, UC, US).

Pithecollobium acuminatum M. E. Jones, Contr. W. Bot.  18: 38.  1933. - TYPE:  MEXICO.  BAJA CALIFORNIA SUR:  above Primiera Aqua near Loreto, 20 Oct 1930, M. E. Jones 27255 (holotype:  RSA).

Formal description

Shrub or small tree to 7 m tall.  Bark dark gray to brown, shallowly furrowed.  Twigs dark purplish brown to dark gray, slightly flexuous, glabrous to puberulent.  Short shoots commonly present above the stipular spines, to 3 mm long, covered with acuminate stipules and old leaf bases.  Leaves alternate, also commonly clustered on the short shoots, 2-6 mm long.  Stipular spines dark reddish brown to gray, symmetrical, terete, straight, thin, to 20(30) x 1.5 mm near the base, usually lightly puberulent.  Petiole adaxially grooved, 2-6 mm long, lightly pubescent; petiolar gland solitary, located near the middle of the petiole to just below the pinna pair, sessile, circular, 0.3-0.7 mm across, apex flat to slightly depressed, glabrous.  Rachis absent.  Pinnae 1 pair per leaf, 8-20 mm long.  Petiolules 0.6-1.8 mm long.  Leaflets 4 to 7 pairs per pinna, opposite, 1.0-3.4 mm between leaflets, oblong, terminal leaflets 4-9 x 1.3-2.5 mm, lateral leaflets slightly smaller, usually pubescent on both surfaces, lateral veins obvious, 1 to 3 veins from the base, base oblique, margins usually ciliate, apex acute and mucronate.  Inflorescence a loosely flowered elongated spike, 15-40 mm long, in clusters of 2 to 8(10) on the short shoots.  Peduncles 0-2 x 0.4-0.7 mm, puberulent.  Involucre usually 4-lobed, at the base of the peduncle, glabrous to puberulent, persistent.  Floral bracts spatulate, 0.3-0.7 mm long, puberulent, deciduous.  Flowers sessile, cream-colored to pale yellow; calyx 4-lobed, 0.4-0.7 mm long, glabrous to lightly puberulent; corolla 4-lobed, 1.1-1.6 mm long, glabrous or nearly so; stamen filaments 3.5-4.9 mm long, distinct; ovary glabrous to lightly puberulent, on a stipe to 0.3 mm long.  Legumes dark reddish brown, straight to slightly curved, flattened, constricted between the seeds, linear, 50-150 x 4-7 mm, coriaceous, reticulately striate, densely lanate, eglandular, dehiscent; a chartaceous pericarpic strip lining each valve; stipe 3-8 mm long; apex acuminate and sometimes beaked.  Seeds uniseriate, no pulp, dark brown, oblong, strongly flattened, 7.0-10.5 x 4.0-5.5 mm, smooth; pleurogram oblong to U-shaped, 1.5-2.4 mm across. Flowers in February to June. Chromosome number:  Not determined.

Distribution

In open disturbed sites and arroyos of the sandy plains below 500 m elevation of Central Baja California south to the Cape Region.

Additional info

Vachellia brandegeana is restricted to the Baja California Sur where it commonly forms extensive thickets.  It is easily distinguished from other taxa in this group by its small leaflets (4-9 x 1.3-2.5 mm) with acute tips, 4-7 pairs of leaflets per pinna, and the densely lanate legumes.  Most of the specimens examined had densely pubescent leaves, though occasional individuals from near La Paz were nearly glabrous.  All specimens examined tested negative for cyanide production (Lee et al. 1989).

Flowering time

February-June.

Representative specimens

MEXICO:

Baja California Sur:

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