Acacia chiapensis x A. pennatula

David S. Seigler & John E. Ebinger, 1995, Taxonomic Revision of the Ant-Acacias (Fabaceae, Mimosoideae, Acacia, Series Gummiferae) of the New World, Annals of the Missouri Botanical Garden 82, pp. 117-138 : 135

Acacia chiapensis x A. pennatula . Shrub or small tree to 5 m tall; twigs brown to dark reddish brown, puberulent. Enlarged stipular spines shiny, reddish brown, puberulent, usually terete in cross section, sometimes ridged or striate, broadly V-shaped with an angle of 160-180° (sometimes slightly reflexed), to 70 mm long, 4.0- 5.5 mm wide near the base. Leaves 70-160 mm long; pinnae 14-30 pairs per leaf; rachis densely puberulent, rachis glands absent except between the terminal 1-3 pinna pairs; petioles grooved, densely puberulent, 4-8 mm long. Petiolar glands 1-3, nearly circular arid with a depressed apex, puberulent, striate, apex 0.9-1.5 mm across. Leaflets 28-36 pairs per pinna, lightly puberulent, linear, 1.9-2.8 mm long, 0.5-0.7 mm wide, one vein from the base, lateral veins not obvious, margins ciliate. Flowers and fruits not observed.

Representative specimen. MEXICO. Oaxaca: edge of road near large dam at Temascal , in pasture near degraded evergreen forest, Seigler et al. 13544 ( EIU, ILL).

Janzen (1974) observed that at two sites (below the dam at Temascal, Río Chichicazapa, and at Arroyo Enmedio, between Temascal, Oaxaca and La Granja, Veracruz, Mexico) Acacia chiapensis may hybridize with non-ant-acacias such as A. macracantha . At this site, numerous plants occurred that were mtermediate in spine, leaf, and branching morphology between these two species. During the present study no hybrids involving A. chiapensis and A. macracantha were found; however, on a recent trip to Temascal (May 1991) the authors collected hybrid specimens of A. chiapensis x A. pennatula . Both parents were common in the pasture where the hybrid was collected and, except for A. cornigera , were the only acacias in the area.