Vachellia globulifera (Saff.) Seigler & Ebinger

Acacia globulifera Safford

Acacia globulifera Safford, 1915:360.

Acacia donnelliana Safford, 1915:361.

Myrmecodendrum globuliferum (Safford) Britton and Rose, 1928:93.

Myrmecodendron donnellianum (Safford) Britton and Rose, 1928:93.

Acacia globulifera is easily distinguished from other swollen-thorn acacias by the possession of spherical inflorescences, completely dehiscent pods with valves that curl back on themselves (as with A. hindsii), and 2 to 6 circular or oval petiolar nectaries (Figures 6, 7C). Its range (Figure 51) overlaps slightly with that of A. collinsii, A. cornigera, A. gentlei, A. cookii, and A. chiapensis, but it is very rarely encountered growing side by side with these plants. Herbarium specimens of A. globulifera are incorrectly listed as a synonym of A. chiapensis in Janzen (1967b), but a comparison of the petiolar nectaries and mature pods—barely indehiscent in A. chiapensis, fully indehiscent in A. globulifera—will easily separate them. The petiolar nectaries of A. globulifera may on occasion be confused with those of A. collinsii, but A. collinsii has elongate inflorescences. In field studies, failure to examine plants closely may result in mis-identifying A. globulifera as A. collinsii or as A. gentlei because it has a very similar life form to either of these when growing in their habitats.

Safford’s type specimen of A. globulifera (site 1) appears to have been taken from a fully insolated shrub growing in a locally exceptionally dry site, since its thorns are unusually light in color (beige) and short (the largest type A thorns are only 4 cm long), and its leaves only attain 8 cm in length. In the coastal areas of the Yucatan Peninsula such plants are usually found on old beach dunes; the more inland plants have thorns that are nearly black and twice as long, and have leaves up to 20 cm long. The inflorescences on the type specimen are representative of A. globulifera throughout its range except that they have peduncles only 10 mm or less in length, and in wetter areas the peduncles of A. globulifera may attain a length of 20 mm.

Safford’s type specimen for A. donnelliana was collected from that portion of the A. globulifera population growing between San Pedro Sula and Santa Rosa, Honduras (site 24), and is representative of the plants in that area growing in very wet habitats (swamps, creek edges); its thorns are nearly black, its leaves are up to 20 cm long, its inflorescence peduncles are up to 18 mm long, and its sexual branchlets are very long (e.g., Figure 52A).

KEY COLLECTION LOCALITIES

Mexico:

1. Type of A. globulifera: Silam (Dzilam), north coast of Yucatan. April 1895, G. F. Gaumer, no. 1909.

2. 48 mi NE Puerto Real (Isla Aguada) on Mexico 180, Campeche. VI–22–1966, DHJ, nos. 611, 615, 617, 623 (occasional), mp.

3. 11.3 mi N intersection of Mexico 185 and 190, on Hgy. 185, Matias Romero, Oaxaca (290 m). VIII–18–1967, DHJ, no. 1502 (single plant).

4. 11.8 mi N intersection of Mexico 185 and 190, on Hgy. 185, Matias Romero, Oaxaca (290 m). VIII–18–1967, DHJ, nc (occasional plants).

5. 25.8 mi N intersection of Mexico 185 and 190, on Hgy. 185, Matias Romero, Oaxaca (250 m). VIII–18–1967, DHJ, nc (very abundant).

6. 26.3 mi N intersection of Mexico 185 and 190, on Hgy. 185, Matias Romero, Oaxaca (240 m). VIII–18–1967, DHJ, nc (3 plants).

7. 31.5 mi N intersection of Mexico 185 and 190, on Hgy. 185, Matias Romero, Oaxaca (260 m). VIII–18–1967, DHJ, nc (1 plant).

8. Chivelia, Oaxaca, Mexico. III–6–1928, C. D. Mell (US 1406953), fl.

9. Silam, Yucatan, Mexico (sea level). IV–1895, G. F. Gaumer, no. 655 (US 1267146), fl.

10. Silam, Yucatan, Mexico (sea level). IV–1909, G. F. Gaumer, (US 1267508) fl.

Guatemala:

11. Finca San Joaquin, slopes above Rio Negro, near San Cristobal de Verapaz, Alta Verapaz (1080 m). VII–14–1967, DHJ, nc (very abundant), mp.

12. 20.5 mi NE Guatemala City on CA9 (980 m). VIII–8–1967, DHJ, no. 1565 (occasional), fl., gp.

13. 26.7 mi to 26.9 mi NE Guatemala City on CA9 (700 m). VIII–9–1967, DHJ, nc (abundant), gp.

14. 29.6 mi NE Guatemala City on CA9 (850 m). VIII–9–1967, DHJ, nc (rare).

15. 23.4 mi SW of turn off to Coban on Hgy. 9, Progreso, Dept. Progreso. VIII–5–1966, DHJ, no. 444.

16. 16.2 mi NE Guatemala City on CA9 (870). V–14–1965, DHJ, no. 1741 (1 plant).

17. Sanarate, Depto. Progreso (900 m). XI–9–1916, Popenoe, no. 720 (US 2089415, US 1319702), mp.

18. La Libertad, Chicbul, Depto. Peten. IV–29–1933, C. L. Lundell, no. 3088 (US 1635206, F 738059), fl.

19. Rio Teculutan, above Teculutan, Depto. Zacapa (250–275 m). 1–7–1942, J. A. Steyermark (F 1191231) fl., mp.

20. Fallabon-Yaxha Rd., Depto. Peten. III–22–1933, C. L. Lundell, no. 2214 (F 740476), mp.