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Name

Vachellia bucheri (Marie-Victorin) Seigler & Ebinger, Phytologia  87:  146.  2005.
syn.  Acacia bucheri Marie-Victorin, Contr. Inst. Bot. Univ. Montréal 49:57. 1945

Synonymy and types

Basionym:  Acacia bucheri Marie-Victorin, Contr. Inst. Bot. Univ. Montréal  49: 57.  1945. - TYPE:  CUBA.  ORIENTE:  Moa, sur la plateforme littorale serpentine-limonitique, 27-31 May 1943, F. Marie-Victorin & Bro. Clément 21804 [holotype:  MT, F photo; isotypes:  F, HAC (Alvarez and Oliver 1991), MO, NY].

Acacia leoni Marie-Victorin. Name appearing on the label of the type specimens of Acacia bucheri, but not in the original description.  Unpublished name.

Formal description

Tree to 8 m tall.  Bark dark reddish brown to gray, rough; the older branches and base of trunk bearing clusters of fusiform to aciculate, straight stipular spines to 80 mm long clustered on short shoots.  Twigs gray to dark reddish-brown, not flexuous, glabrous. 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; 3-14 mm long.  Stipular spines reddish-brown, becoming gray with age, symmetrical,  terete, straight, aciculate to 20.0 x 0.8 mm near the base, glabrous.  Petiole adaxially grooved, 3.0-14.0 mm long, glabrous; petiolar gland solitary, located just below the pinna pair, sessile to subsessile, apex circular to elliptical, 0.4-1.3 mm across, depressed, glabrous.  Rachis absent.  Pinnae 1 pair per leaf, (28)36-52 mm long. Petiolules 0.8-1.5 mm long.  Leaflets (16)27 to 39 pairs per pinna, opposite, 0.8-1.6 mm between leaflets, linear to oblong, 3.4-7.5 x 0.7-1.3 mm, glabrous, lateral veins not obvious, only one vein from the base, coriaceous, base oblique, margins not ciliate, apex obtuse.  Inflorescence a densely flowered globose head, 4.7-7.5 mm across, in fascicles of 1 to 5 from the short shoots.  Peduncles 7-16 x 0.4-0.6 mm, glabrous.  Involucre 4- to 5-lobed, located at the base of the head, glabrous, persistent.  Floral bracts spatulate, 0.5-0.8 mm long, sparsely puberulent, deciduous.  Flowers sessile, yellow; calyx 5-lobed, 0.8-1.1 mm long, glabrous; corolla 5-lobed, 1.8-2.3 mm long, glabrous; stamens 40 to 50, stamen filaments 2.7-3.5 mm long, distinct to connate near the base; ovary glabrous, on a stipe to 0.3 mm long.  Legumes dark blackish-brown, straight to slightly curved, elliptical in cross section, usually strongly constricted between the seeds, linear, 40-80 x 4-6 mm, coriaceous, rugose but not striate, glabrous and lustrous, eglandular, dehiscent along the ventral suture; stipe 2-5 mm long; apex narrowing to an acuminate beak.  Seeds uniseriate, surrounded by a reddish-brown pulp, light to dark brown, ellipsoid, slightly flattened, 3.8-4.5 x 2.8-3.6 mm, smooth; pleurogram oval, 1.6-2.5 mm across.  Flowers in May.  Chromosome number unknown.

Distribution

Restricted to arid, serpentine areas in Holguín Province and Guantánamo Province, Cuba.  In the original description, Marie-Victorin (1945) cited the occurrence of this taxon from near Moa and near Baracoa, Holguín Province.  Bisse (1988) cited its occurrence from near Guantánamo, on limestone, as well as serpentine.

Additional info

Vachellia bucheri is known from only three localities, all from Guantánamo and Holguín provinces, Cuba.  It is separated from all members of the Vachellia acuifera group, except V. acuifera, by its globose receptacle, involucre at the base of the globose head, petioles mostly more than 4 cm long and pinnae mostly more than 36 mm long.  It is distinguished from V. acuifera by having 22 or more pairs of leaflets per pinna (vs 18 or fewer in A. acuifera) and leaflets less than 1.3 mm wide and leaflet pairs less than 1.7 mm apart on the pinnae.  Superficially, this taxon resembles V. daemon, but V. daemon has shorter petioles, shorter pinnae and involucral bracts near the middle of the peduncle. The name Vachellia leoni Marie-Victorin appears on the label of the type specimens, but not in the original description.

Monte Líbano, the locality near Guantánamo where this species was collected, has been described by Borhidi (1991) as an important center of evolution for the karst flora of Cuba.  The extent to which this is an important factor in the evolution of the Cuban acacias is unknown, although two, A. zapatensis and A. bucheri, are also known from limestone areas.  The extent of the acacias in these areas is quite limited, and may constitute a secondary radiation that followed the spread of this group onto serpentine areas.  More thorough collecting of these species, to determine the extent to which they occur on both serpentine and limestone, will be necessary to evaluate fully their edaphic responses.  None of the 10 collections tested positive for cyanide, even after the addition of emulsin.

Borhidi (1991) makes a distinction between the serpentine habitats occupied by Vachellia bucheri and those occupied primarily by V. daemon.  The former are termed charrascales and are slightly higher in elevation and more mesic than the latter that are termed cuabales.  This observation correlates to a certain extent with the morphological differences of these two taxa:  V. bucheri is a somewhat more robust plant with more luxuriant foliage than V. daemon.  These differences may be the result of adaptation to slightly different climatic conditions.  In this view, the charrascales of eastern Cuba are thought to represent a source area for speciation onto the cuabales of central and western Cuba.  These occurence of V. daemon in eastern Cuba in the same localities as V. bucheri, may present a challenge to this model, if the occurrence of V. daemon in these areas is not the result of a secondary migration eastward after its origin on the cuabales of western Cuba.

Representative specimens

CUBA:

Guantánamo Province: 

Holguín Province:

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