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Vachellia schaffneri - habit

Vachellia schaffneri

Vachellia schaffneri - branch

Vachellia schaffneri

Vachellia schaffneri

Vachellia schaffneri

Vachellia schaffneri - pods

Vachellia schaffneri - spines

Vachellia schaffneri - habit

Vachellia schaffneri - habit

Vachellia schaffneri

Vachellia schaffneri - branch

Vachellia schaffneri

Vachellia schaffneri - spines

Vachellia schaffneri - leaves

Vachellia schaffneri - spines

Vachellia schaffneri - spines

Vachellia schaffneri - habit

Name

Vachellia schaffneri (S. Watson) Seigler & Ebinger, Phytologia  87:  167.  2005.
syn.  Acacia schaffneri (S. Watson) F. J. Hermann, J. Wash. Acad. Sci. 38:  236.  1948.

Synonymy and types

Basionym:  Pithecellobium schaffneri S. Watson, Proc. Amer. Acad. Arts  17: 352.  1882.  Samanea schaffneri (S. Watson) J. F. Macbr., Contr. Gray Herb.  59: 2.  1919.  Popanax schaffneri (S. Watson) Britton & Rose, N. Amer. Fl.  23: 89.  1928.  Acacia schaffneri (S. Watson) F. J. Herm., J. Wash. Acad. Sci.  38: 236.  1948. - TYPE:  MEXICO.  SAN LUIS POTOSÍ:  in the mountains about San Luis Potosí, C. C. Parry & E. Palmer 219 [lectotype, designated by Rzedowski (1963):  GH].

Acacia subtortuosa Shafer in Britton & Shafer, N. Amer. Trees,  524.  1908. - TYPE:  MEXICO.  DURANGO:  near the city of Durango, Apr - Nov 1896, E. Palmer 11 (holotype:  NY; isotypes:  F, MO, UC).

Formal description

Shrub or small tree to 10 m tall.  Bark grayish brown, shallowly furrowed.  Twigs dark purplish brown to dark brown, slightly flexuous, usually densely pubescent with erect hairs.  Short shoots commonly present above the stipular spines, to 5 mm long, covered with acuminate stipules and old leaf bases.  Leaves alternate, commonly clustered on the short shoots, 5-20 mm long.  Stipular spines light to dark brown, usually becoming light gray with age, symmetrical, terete, straight, thin to stout, to 15(30) x 1.5 mm near the base, usually pubescent at least near the base.  Petiole adaxially grooved, 2-8 mm long, usually densely pubescent with erect to ascending hairs; petiolar gland solitary, located at or just below the lower pinna pair, sessile, circular, 0.2-1.1 mm across, doughnut-shaped, finely puberulent. Rachis adaxially grooved, 0-18 mm long, pubescent, usually a sessile, circular gland 0.1-0.3 mm across, between the terminal and occasionally the other pinna pairs.  Pinnae (3)4 to7 pairs per leaf, 7-28 mm long, 2-8 mm between pinna pairs.  Petiolules 0.4-1.0 mm long.  Leaflets 10 to 19 pairs per pinna, opposite, 0.5-1.1 mm between leaflets, oblong, 2.0-4.2(5.0) x 0.6-1.1 mm, pubescent beneath with erect hairs, lateral veins sometimes obvious, only one vein from the base, base oblique, margins ciliate, apex broadly acute to obtuse.  Inflorescence a densely flowered globose head, 8-11 mm across, solitary or in clusters of 2 to 5 on the short shoots.  Peduncles 7-24 x 0.3-0.9 mm, densely pubescent, and small, red, deciduous glands also present.  Involucre 4- to 5- lobed, located at the base of the globose head, lightly pubescent, persistent.  Floral bracts spatulate, 0.8-1.3 mm long, puberulent, deciduous.  Flowers sessile, yellow; calyx 5-lobed, 0.8-1.6 mm long, the lobes glabrous to puberulent; corolla 5-lobed, 2-3 mm long, the lobes glabrous to puberulent; stamen filaments 3.2-4.2 mm long, distinct; ovary glabrous to densely pubescent, on a stipe to 0.2 mm long.  Legumes dark brown to black, straight to slightly curved, flattened, not constricted between the seeds, linear, 70-160 x 9-13 mm, coriaceous, recticulately striate, densely pubescent with erect hairs, glandular with minute, red, deciduous glands, indehiscent; stipe to 4 mm long; apex acute to obtuse.  Seeds uniseriate, no pulp, light to dark brown, ovoid, slightly flattened, 6.0-9.1 x 5.0-6.5 mm, smooth; pleurogram oval, 3.1-5.0 mm across.  Flowers in February to April.  Chromosome number:  2n = 26 (Turner and Fearing 1960).

Distribution

On relatively dry sites with various soils, in pastures, successional fields and other disturbed sites between 600 and 2500 m elevation from south Chihuahua and Coahuila, south to Veracruz and northern Oaxaca, Mexico.

Additional info

Individuals of Vachellia schaffneri are distinguished from those of V. bravoensis, by the broader (9-13 mm across) fruits that are not constricted between the seeds, the thicker twigs (2.5-4 mm thick), the leaves with more pinna pairs (mostly 4-7 on the primary leaves), leaflets that are pubescent beneath, and the overall size of the plant (to 10 m tall).  Although somewhat variable in these traits, the pubescence on the underside of the leaflets appears to be very consistent, and when only primary leaves (those developing at the nodes on new growth) are considered, the number of pinna pairs is a very usable characteristic as V. bravoensis usually has 3 or fewer pinna pairs.  Also, V. schaffneri is usually found at higher elevations, and has a more southerly distribution, being largely restricted to central Mexico.  According to Rzedowski (1978), V. schaffneri is an ecologically important species of the arid to semi-arid regions at moderately high altitudes, and often is the dominant woody species.

The specimens examined showed little variation with respect to most characteristics, the most variable trait being the number of pinna pairs on a leaf.  Generally, the primary leaves on new growth are larger, with more pinna pairs than the leaves that developed from the short shoots.  Usually the primary leaves have from 4-7 pinna pairs, a petiole that is less than 3 mm long, a rachis to 18 mm long, and a larger petiolar gland (0.5-1.1 mm across).  Short shoot leaves, in contrast, have 1-4 pinna pairs, a petiole that is usually more than 3 mm long, a rachis that rarely exceed 10 mm in length, and petiolar gland that is mostly less than 0.5 mm across.  All of the specimens examined were either strongly to moderately cyanogenic.  The cyanogenic glycoside present is proacacipetalin (Seigler et al. 1978).

The specimen cited in the original description (Watson 1882) consists of three separate collections on a single sheet: Schaffner 623, Schaffner 628 and Parry & Palmer 219. Schaffner 623 and 628, consist of material that is mostly Pithocellobium leptophyllum (Cav.) Daveau with a small amount of V. schaffneri material included.  The Parry & Palmer 219 collection, however, consists entirely of V. schaffneri material and was designated the lectotype (Rzedowski 1963).

Besides Vachellia bravoensis, the only species that V. schaffneri is likely to be confused with is Vachellia astringens (syn. Acacia atramentaria), a species restricted to northern Argentina, far south of the range of V. schaffneri.  Both taxa have a large doughnut-shaped gland between the lower most pinna pairs.  Vachellia atramentaria, however, has primary leaves that exceed 20 mm in length and petiolules that are more than 1 mm long.  In V. schaffneri, in contrast, the primary leaves are usually less than 20 mm long and the petiolules are shorter.

Flowering time

February-April.

Representative specimens

MEXICO:

Aguascalientes:

Chihuahua:

Durango:

Guanajuato:

Hidalgo:

Jalisco:

Mexíco:

Nuevo León:

Oaxaca:

Puebla:

San Luis Potosí:

Tamaulipas:

Veracruz:

Zacatecas:

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