ABCDEFGHIJKLMNOPQRSTUVWXYZ

Name

Vachellia anagadensis (Britton) Seigler & Ebinger, Phytologia  87:  142.  2005.
syn.  Acacia anagadensis Britton, Mem. New York Bot. Gard. 6:  572.  1916.

Synonymy and types

Basionym:  Acacia anegadensis Britton, Mem. New York Bot. Gard. 6:  572.  1916.  Fishlockia anegadensis (Britton) Britton & Rose, N. Amer. Fl.  23: 91.  1928. - TYPE:  BRITISH VIRGIN ISLANDS.  Anegada, rocky plains, The Settlement, 19-20 Feb 1913, N. L. Britton & W. C. Fishlock 990 (holotype:  NY; isotypes:  F, GH, NY, US).

Formal description

Tree to 8 m tall.   Bark dark brown to reddish brown to gray, rough; the older branches and the trunks of young trees usually bearing clusters of fusiform to  aciculate, straight stipular spines to 80 mm long clustered on short shoots.  Twigs gray to dark reddish-brown, flexuous, puberulent.  Short shoots usually 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, 1.3-5.1 mm long.  Stipular spines redish-brown, becoming gray with age, symmetrical, terete, straight to slightly recurved, aciculate, to 12.0 x 0.9 mm near the base, glabrous to lightly puberulent. Petiole adaxially grooved, 1.3-5.1 mm long, glabrous to lightly puberulent; petiolar gland solitary, located just below the first pinna pair, columnar, 0.2-0.6 mm long, the expanded apex circular to elliptic, 0.3-0.7 mm across, glabrous, depressed.  Rachis absent.  Pinnae 1 pair per leaf, 2.5-15.5 mm long.  Petiolules 2-5 mm long.  Leaflets 1 to 3(4) pairs per pinna, opposite, 2.5-6.0 mm between leaflets, oblong to obovate, (6.5)10-16 x 5.5-10.3 mm, glabrous, lateral veins obvious, 3-7 veins from the base with obvious eucamptodromous venation, coriaceous, base oblique, margins not ciliate, apex obtuse and emarginate.  Inflorescence a densely flowered globose to subglobose head, 5-9 mm across, in fascicles of 1 to 4 from the short shoots.  Pedicels 5-15 x 0.4-0.7 mm, puberulent.  Involucre 4- to 5-lobed, located 1-2(5) mm below the base of the head, lightly puberulent, persistent.  Floral bracts spatulate, 0.3-0.7 mm long, sparsely puberulent, more or less persistent.  Flowers sessile, bright orange to yellow; calyx 5-lobed, 0.6-1.1 mm long, glabrous the lobes puberulent; corolla 5-lobed, 1.5-2.1 mm long, glabrous or nearly so; stamens 15 to 25, stamen filaments 3.0-4.2 mm long, distinct; ovary pubescent, on a stipe to 0.7 mm long.  Legumes reddish-brown to dark blackish brown, slightly curved to almost falcate, elliptic in cross section, not constricted between the seeds, oblong, 30-45 x 7-9 mm, coriaceous, irregularly striate, glabrous and lustrous, eglandular, dehiscent along the ventral suture; stipe 3-7 mm long; apex acute.  Seeds uniseriate, surrounded by a reddish-brown pulp, light to reddish-brown, irregularly ellipsoid to ovoid, slightly flattened, 3.8-4.5 x 2.7-3.5 mm, smooth; pleurogram oval, 1.9-2.6 across.  Flowers year around.  Chromosome number unknown.

Distribution

Known only from the island of Anegada, British Virgin Islands.  Found on dry, rocky or sandy soil near sea level (Britton 1916).  D'Arcy (1971) and Little et al. (1974) indicate that this species is threatened by development.

Additional info

The unusual leaflet morphology of V. anegadensis led D'Arcy (1971) and Little et al. (1974) to suggest a similarity to various Pithecellobium species (sensu Barneby and Grimes).  Despite this unusual leaflet venation, the affinities of this species lie clearly within the V. acuifera species group, with its coriaceous leaflets, elongate-clavate receptacle, fruits dehiscent along the ventral suture, and the presence of enlarged stipular spines on the short shoots of older growth.  Two of the collections examined (D'Arcy 4909c and 4976) are of juveniles that have elliptic-oblong leaflets with 4 pairs per pinna.  These two collections were the only specimens found to be cyanogenic.  The occurrence of cyanogenesis in young foliage or in juvenile plants, but not in mature foliage or adults, is a pattern typical of many acacias.

The affinity of Vachellia anegadensis appears to lie with the Hispaniolan species (V. barahonensis, V. caurina, V. cucuyo, and V. oviedoensis).  It shares with the first three of these taxa an involucre position a few millimeters below the flowering head, an elongate-clavate receptacle, a columnar petiolar gland that is usually inclined toward the apex of the petiole an situated at of near the lower pinna pair.  It shares with V. barahonensis, V. cucuyo, and V. oviedoensis an unusually low stamen number (< 35), and shares with V. cucuyo a turgid and oblong, though somewhat smaller fruit.  Vachellia anagadensis is morphologically very similar to V. oviedoensis in having one pair of pinnae per leaf with usually only one pair of relatively large leaflets per pinna.

Vachellia anegadensis is a quite distinctive species of extremely limited distribution and on the basis of the few specimens available, significant variation was not detected.  It is well differentiated from other species and may be identified on the basis of the combination of leaves with only one pair of pinnae, large, oblong to obovate leaflets > 7 mm wide with obvious eucamptodromous venation, and mostly 1 to 2 pairs of leaflets per pinna.  Vachellia chloriophylla is the only other species in the Caribbean islands with large leaflets, but it is otherwise very dissimilar, having > 1 pair of pinnae per leaf, and 4 to 7 pairs of leaflets per pinna.

Representative specimens

BRITISH VIRGIN ISLANDS:

Anegada: 

Top