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Name

Mariosousa mammifera (Schlechtendal) Seigler & Ebinger

Synonymy and types

Acacia mammifera Schlechtendal, Linnaea 12:563. 1838. - Senegalia mammifera (Schlechtendal) Britton & Rose, N. Amer. Fl. 23:112. 1928. - TYPE: Mexico, Hidalgo, Barranca de Acholoya, Nov., C.Ehrenberg s.n. (holotype: HAL!, isotypes: UC!).

Formal description

Shrub or small tree to 5 m tall. Bark dark gray, shallowly fissured.  Twigs light brown to purplish-brown, not flexuous, usually puberulent and, when young, commonly with minute purple glands.  Short shoots absent.  Leaves alternate, 30-130 mm long. Stipules herbaceous, light brown, narrowly triangular, to 2.5 x 0.6 mm near the base, glabrous to puberulent, persistent.  Petiole adaxially grooved, 8-50(70) mm long, usually lightly puberulent and commonly with minute purple glands; petiolar gland solitary, located between the lower pinna pair or rarely along the upper half of the petiole, stalked, circular, 0.4-0.8 mm across, apex globose, glabrous.  Rachis adaxially grooved, 10-70 mm long, puberulent and commonly with minute purple glands, a stalked gland with a globose apex, 0.4-0.6 mm across, between the pinnae of most pinna pairs.  Pinnae 1 to 6(9) pairs per leaf, 30-85 mm long, 6-15(25) mm between pinna pairs.  Petiolules 2.0-2.8(4.5) mm long.  Leaflets 10 to 26(33) pairs per pinna, opposite, 1-5 mm between leaflets, oblong, 4-12 x 1.5-3.5 (4.5) mm, loosely pubescent on both surfaces with appressed hairs, commonly purplish above, light green to purplish-green beneath, lateral veins obvious, a midvein and 1 to 3 smaller veins from the base, base oblique, margins ciliate, apex obtuse to broadly acute.  Inflorescence a loosely flowered cylindrical spike 30-90 mm long, solitary (rarely 2) from the leaf axil. Peduncle 6-15 x 0.7-1.1 mm, puberulent and with minute purple glands.  Involucre absent.  Floral bracts linear, to 1.4 mm long, pubescent, early deciduous.  Flowers sessile, creamy-white; calyx 5-lobed, 1.3-2.0 mm long, lightly appressed pubescent; corolla 5-lobed, 2.2-3.5 mm long, lightly appressed pubescent; stamen filaments 6.5-8.5 mm long, distinct; ovary glabrous, on a stipe to 0.3 mm long.  Legumes light yellowish-brown to dark greenish-brown, straight, flattened, not constricted between the seeds, oblong, 80-240 x 18-35 mm, cartilagious, transversely striate, glabrous, eglandular, dehiscent along both sutures; stipe to 12 mm long; apex acuminate and usually beaked.  Seeds uniseriate, no pulp, dark brown, nearly circular, strongly flattened, 8.0-10.5 mm across, smooth; pleurogram U-shaped, 3-4 mm across.   Flowers: April-June.  Chromosome number: Not determined.

Distribution

Thorn scrub forests and from the pinion-Juniper zone in dry thickets, and rocky slopes from 1300 to 2700 m elevation in eastern Mexico from the state of Tamaulipas and Nuevo Leon south to Oaxaca.

Additional info

Mariosousa mammifera is widely distributed throughout the central part of Mexico from the state of Oaxaca, north to Tamaulipas and Nuevo León.  It does not appear to be a common species, however, many of the collections being from near the same localities in the various states.  All collections examined are from above 1300 m, many from near the pinon-Juniper zone, or rocky slopes, and dry thickets, mostly associated with thorn -scrub vegetation.

The few pinna pairs, the large leaflets with appressed hairs on both surfaces, the dull purple color on the upper surface of the leaflets, the narrowly triangular stipules and the stalked petiolar glands can be used to separate Mariosousa mammifera from other members of this group.  Also, the mature fruits of M. mammifera are commonly more than 30 mm broad and up to 240 mm long, much larger than is typical of fruits of most species.  The minute, stalked purple glands that occur on the petiole, rachis, pinna rachis and the peduncle of most specimens, particularly on new growth, is a reliable characteristic that this species shares with M. acatlensis, M. compacta, and M. sericea.  Usually these small glands are not very dense, being widely scattered on the petiole, rachis and peduncle; on the pinna rachis, however, these glands are usually densely packed around the base of most leaflets.

This species is not known to hybridize with other Mariosousa taxa, but one unusual specimen from Puebla, Mexico, was encountered [E.Martinez S. 21665 (MEXU)].  This was a small, compact plant with small leaves and leaflets of, but was similar to M. mammifera in lacking short shoots, having narrowly triangular stipules, a stalked petiolar gland with a bulbous apex, and leaflets that were purplish and pubescent on both surfaces.  Occurring at an elevation of 2300 m, this specimen was probably outside the natural range of M. compacta. The status of this possible hybrid must await additional field
studies.

Flowering time

April-June.

Representative specimens

MEXICO:

Guanajuato:

Hidalgo:

Nuevo León:

Oaxaca:

Puebla:

Querétaro:

San Luís Potosí:

Tamaulipas:

UNITED STATES:

Arizona:

Pima Co.:

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