Vachellia tortuosa - flower

Vachellia tortuosa - fruit

Vachellia tortuosa - habit

Vachellia tortuosa - habit

Vachellia tortuosa - inflor

Vachellia tortuosa - leaf

Vachellia tortuosa - spines

Vachellia tortuosa - raceme


Vachellia tortuosa (Linnaeus) Seigler & Ebinger, Phytologia 87:  168.  2005.
syn.  Acacia tortuosa (Linnaeus) Willdenow. Sp. pl.  4:  1083.  1806.

Synonymy and types

Basionym:  Mimosa tortuosa L., Syst. Nat., 10th ed.,  2: 1312.  1759.   Acacia tortuosa (L.) Willd.  Sp. Pl.  4: 1083.  1806.   Poponax tortuosa (L.) Raf., Sylva tellur. 118.  1838. - TYPE:  JAMAICA.  without exact locality, Patrick Brown(e) s.n. (holotype:  LINN, microfiche).

Acacia virescens DC., Cat. pl. horti monsp.  74.  1813. - TYPE:  probably South American, the species was described from a plant grown in the Botanical Garden in Montpellier.  The seeds for this plant were obtained from the Botanical Garden in Madrid. (holotype:  G-DC, microfiche).

Acacia leucacantha Bertero, Spreng., Syst. veg.  3: 144.  1826. - TYPE:  JAMAICA.  C. G. Bertero s.n. [lectotype, designated by Ebinger et al. (2000):  MO].

Acacia seifriziana León in León and Alain. Contr. Ocas. Mus. Hist. Nat. Colegio "De La Salle"  9: 8.  1950. - TYPE:  CUBA.  ORIENTE:  low forest near Maisí, Jul 1938, León and Seifriz 18351 (holotype:  HAC).  NOTE:  We have not been able to examine the type, however, based on the description, it appears referable to Acacia tortuosa, a conclusion also advanced by Bässler (1998).

Mimosa salinarum Rohr ex Benth., Trans. Linn. Soc. London  30: 501.  1875. - TYPE:  none cited.

Formal description

Shrub or small tree to 6 m tall.  Bark dark gray to dark brown, shallowly furrowed.  Twigs dark purplish brown to dark gray, strongly flexuous, usually pubescent.  Short shoots commonly present above the stipular spines, to 10 mm long, covered with acuminate stipules and old leaf bases.  Leaves alternate, also commonly clustered on the short shoots, 12-45 mm long.  Stipular spines light to dark brown to purplish, sometimes becoming light gray with age, symmetrical, terete, straight, stout, to 40 (55) x 1.5 mm near the base, densely pubescent at least toward the base, glabrousPetiole adaxially grooved, 3-7 mm long, usually densely pubescent with erect hairs; petiolar gland solitary, located medially to near the base of the lowermost pinna pair, sessile, elongated to circular, 0.3-2.0 mm long, apex depressed, glabrousRachis adaxially grooved, 5-40 mm long, usually densely pubescent with long, straight hairs, a sessile, circular gland, 0.3-0.4 mm across between the upper 1 to 2 pinna pairs.  Pinnae 2 to 8 pairs per leaf, 12-23 mm long, 3.2-7.5 mm between pinna pairs.  Petiolules 0.5-1.4 mm long.  Leaflets 11 to 19 pairs per pinna, opposite, 0.8-1.7 between leaflets, oblong, (2.5) 3.0-5.5 x 0.9-1.5 mm, glabrous or nearly so, lateral veins more or less evident, only one vein from the base, base oblique, margins strongly ciliate, apex broadly acute to obtuseInflorescence a densely flowered globose head, 6-9 mm across, solitary to clusters of 2 to 5 on the short shoots.  Peduncles 12-36 x 0.4-0.7 mm, lightly puberulent and usually with minute, red, deciduous glands.  Involucre 4- to 6- lobed, located at the base of the globose head, glabrous to lightly puberulent, persistent.  Floral bracts spatulate, 0.8-1.5 mm long, puberulent, deciduous.  Flowers sessile, pale yellow; calyx 5-lobed, 1.1-1.8 mm long, the lobes pubescent; corolla 5-lobed, 1.5-2.4 mm long, the lobes pubescent; stamen filaments 3.5-4.5 mm long, distinct; ovary glabrous, on a stipe to 0.2 mm long.  Legumes dark brown to black, straight to slightly curved, elliptical in cross section, constricted between the seeds, linear (65) 80-150 x 5-9 mm, coriaceous, strongly reticulately striate, pubescent, usually glandular with minute, reddish glands, indehiscent; stipe to 7 mm long; apex acuminate.  Seeds uniseriate, no pulp, light brown, ellipsoid to ovoid, slightly flattened, 5.3-6.8 x 3.5-5.0 mm, smooth; pleurogram U-shaped to nearly oval, 2.5-4.0 mm across. Flowers intermittently throughout the year. Chromosome number:  2n = 26 (Atchison 1948).


Thickets, open pastures, successional fields, and on dry sites, from sea level to about 1100 m in extreme southern Florida and the Bahamas south through the West Indies to Colombia and western Venezuela (Clarke et al. 1989).

Additional info

Vachellia tortuosa is a lowland species, occurring at or near sea level in southern Florida and the West Indies where it is the dominant and co-dominant of the woody vegetation in scrub thickets.  Its presence in extreme southern Florida was probably the result of pre-Columbian introduction, as Ward (1968) found that this species was always associated with sites of human occupation.  In South America it is also commonly a lowland species, but a few specimens were collected at elevations as high as 1100 m.  Presently, this taxon is not known from Mexico or most of Central America.

Most of the variation in Vachellia tortuosa is related to the differences in leaves on short shoots, and the leaves originating from between the stipular spines on rapidly growing branches.  The smaller leaves with fewer and shorter pinnae, and small, circular petiolar glands occur on the short shoots.  More and longer pinnae, and a larger, elongated petiolar gland occur on the primary leaves.  Also, young stems are commonly flexuous, but sometimes this is not very obvious on slow growing branches.

Vachellia tortuosa is closely related to V. farnesiana, and these taxa are sometimes considered conspecific. Both have short shoots just above the stipular spines, the bipinnately compound leaves generally have less than 7 pairs of pinnae, whereas the leaflets are relatively large (3-6 mm long) and closely spaced along the costa. Some traits, however, can be used for consistent separation, particularly mature fruits.  In V. tortuosa the fruits are relatively long (80-150 mm) and narrow (5-9 mm), densely pubescent, and constricted between the seeds; whereas in V. farnesiana the fruits are shorter (30-90 mm), broader (10-18 mm), usually glabrous, inflated, and not constricted between the seeds. Without fruits consistent separation is still possible as in V. tortuosa the petioles, rachises, and spines are densely pubescent, the petioles, even on primary leaves, are less than 7 mm long, the leaflets are strongly ciliate, and the calyx and corolla lobes are densely puberulent.  In V. farnesiana, in contrast, the plants are usually glabrous to only lightly pubescent, the petioles on the primary leaves are up to 12 mm long, the leaflets are not, or only slightly ciliate, and the calyx and corolla lobes are commonly glabrous.  The petiolar glands of the smaller leaves of V. tortuosa, particularly those on the short shoots, are small and circular, similar to those in V. farnesiana.  The leaves on rapidly growing branches, however, have petiolar glands that are much larger and usually elongated.

The only other species within its range with which Vachellia tortuosa could be confused is V. guanacastensis.  However, the larger leaves with consistently 7-9 pinna pairs, and the pinnae with more than 20 leaflet pairs in V. guanacastensis, separates this species from V. tortuosa. In the past, V. tortuosa has also been confused with V. bravoensis (Turner 1959, Isely 1969). The circular petiolar gland between the lower pinna pair in V. schaffneri consistently separates this species from V. tortuosa.

Clarke et al. (1989) found that nearly all specimens (95%) of this taxon from Central and North America were weakly cyanogenic.  Of the 75 specimens tested from South America almost all (96%) gave a positive reaction, but the reaction was weak and slow to develop.  In some cases, living material of this species gives a rapid, positive reaction for cyanide.

Flowering time

Intermittently throughout the year.

Representative specimens



Collier Co.:

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