Vachellia chiapensis (Saff.) Seigler & Ebinger

Acacia chiapensis Safford

Acacia chiapensis Safford, 1915:356.

Acacia chiapensis is known only from Mexico (Figure 44) and the type specimen was collected at the same site as the type of A. collinsii (site 1). A. chiapensis is distinguishable from all other swollen-thorn acacias by the combination of globular inflorescences, multiple and circular petiolar nectaries, semi-indehiscent seed pods, and straight or slightly curved thorns that are circular in cross section. It is easily distinguished from A. collinsii, since the latter species has elongate inflorescences and few petiolar nectaries. The type specimen of A. chiapensis is representative of its species throughout the range except that the single type A thorn is light brown, while A. chiapensis thorns are usually dark brown to black. The immature seed pods on the type specimen are full-sized and display the distinct ridge bordering the margins of the valves, which is characteristic of A. chiapensis, and absent from other swollen-thorn acacias.

KEY COLLECTION LOCALITIE (ALL IN MEXICO)

1. San Fernando, Chiapas. VII–12–1907, G. N. Collins, no. 164.

2. Shores of lake behind Presa Miguel Aleman, Temascal, Oaxaca (70 m). XI–3–1963, DHJ, nc (occasional).

3. Temascal, Oaxaca to La Granja, Veracruz (16 m). All year, DHJ, nos. 118, 130, 140, 154, 158, 164, 165, 170, 185, 190, 193, 200, 204, 209, 214, 222, 230, 235, 242, 247, 266, 277, 281 (common in permanently wet sites such as below the dam at Temascal, Rio Chichicazapa, and Arroyo En-medio, very rare otherwise).

4. 3.4 to 8.5 mi E Papaloapan on Cd. Aleman-Loma Bonita Hgy., Oaxaca (25 m). XI–4–1963, DHJ, nc (3 plants).

5. 19.6 mi SW Tuxtepec on Tuxtepec-Oaxaca Hgy., Oaxaca. XI–4–1963, DHJ, nc (1 plant).

6. 26.4 mi SW Tuxtepec on Tuxtepec-Oaxaca Hgy., Oaxaca. XI–4–1963, DHJ, nc (common).

7. 0.9 mi S Chontalpa on Cardenas-Presa Malpaso Rd., Tabasco (about 80 m). VI–17–1966, DHJ, nc (3 plants).

8. 12.6 mi W Cardenas on Hgy. 180, Tabasco (30 m). VI–15–1966, DHJ, nc (1 plant), fl.

9. 15.1 mi S and 5.2 to 11.0 mi N turn-off to Matias Romero on Hgy. 185, Oaxaca (300–160 m). VIII–18–1967, DHJ, nos. 1500, 1510 (8 plants).

Vachellia chiapensis is a species of leguminous tree in the family Fabaceae. It is found only in Mexico.