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Name

Vachellia caurina (Barneby & Zanoni) Seigler & Ebinger, Phytologia  87:  148.  2005.
syn.  Acacia  caurina Barneby & Zanoni, Moscosoa 5:  20.  1989.

Synonymy and types

Basionym:  Acacia caurina Barneby & Zanoni, Moscosoa  5: 20.  1989. - TYPE:  HAITI.  NORD-OUEST.  sprawling shrub on rocks, arid, steep mountain slope west of bay, vicinity of Port ŕ l'Écu, 15-17 Mar 1929, E. C. Leonard & G. M. Leonard 13863 (holotype:  US; isotypes:  A, GH, NY).

Formal description

Sprawling shrub to 1 m tall. Bark light gray, smooth.  Twigs gray to dark reddish-brown, not flexuous, puberulent.  Short Shoots commonly present above the stipular spines, to 2 mm long, covered with acuminate stipules and old leaf bases.  Leaves alternate, also commonly clustered on the short shoots, 0.4-1.4 mm long.  Stipular spines reddish-brown, becoming gray with age, symmetrical, terete, straight, aciculate, to 5.5 x 0.6 mm near the base, sparsely puberulent.  Petiole adaxially grooved, 0.4-1.4 mm long, puberulent; petiolar gland solitary, located just below the pinna pair, columnar, 0.3-0.8 mm long, commonly inclined toward the apex of the petiole, apex circular, glabrous, depressed, 0.2-0.5 mm across.  Rachis absent.  Pinnae 1 pair per leaf, 3-9 mm long.  Petiolules 0.3-0.6 mm long.  Leaflets 5 to 9 pairs per pinna, opposite, 0.4-1.1 mm between leaflets, oblong to slightly obovate, 1.6-3.2 x 0.8-1.2 mm, lightly puberulent to glabrous, lateral veins not obvious, only one vein from the base, coriaceous, base oblique, margins ciliate, apex obtuse.  Inflorescence a densely flowered globose to slightly subglobose head, 5-7 mm across, in fascicles of 1 to 3 from the short shoots.  Peduncles 6-14 x 0.3-0.5 mm, puberulent.  Involucre 4- to 6-lobed, located 1-3 mm below the base of the head, lightly puberulent, persistent.  Floral bracts spatulate, 0.4-0.8 mm long, sparsely puberulent, more or less persistent.  Flowers sessile, greenish-yellow; calyx 5-lobed, 0.7-1.0 mm long, glabrous, the lobes puberulent; corolla 5-lobed, 1.3-1.8 mm long, glabrous or nearly so; stamens 45 to 50, stamen filaments 2.1-3.0 mm long, commonly fused near the base; ovary pubescent with appressed hairs, on a stipe to 0.2 mm long.  Legumes unknown.  Seeds unknown.  Flowers in March. Chromosome number unknown.

Distribution

Known only from the type locality near Port-ŕ-l'Écu, Department Nord-Ouest, Haiti.

Additional info

Endemic to Haiti, Vachellia caurina is known only from a few collections at the type locality.  All collections lack fruits and enlarged stipular spines on the short shoots of older growth, but the species may still be placed with confidence in the V. acuifera species group.  Liogier (1985) referred the two collections of this species with reservations to Vachellia barahonensis.  Later, Barneby and Zanoni (1989) recognized this taxon as a separate species, pointing out a number of ways in which it differs from V. barahonensis.  The present treatment also recognizes the distinctive nature of V. caurina, but in the absence of recent collections, particularly fruiting material, a thorough understanding of this species remains elusive.  Vegetatively, however, V. caurina does appear in many characteristics to be a diminutive form of V. barahonensis.  Both species are distinguished from other members of the V. acuifera species group by having oblong to slightly obovate leaflets, with 4 to 11 pairs per pinna.  No specimens of V. caurina were found to be cyanogenic, even after the addition of emulsin.

Representative specimens

HAITI:

Department Nord-Ouest:

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