Acacia

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 : 120-121

KEY TO THE SPECIES OF ANT ACACIAS

la. Petiolar glands usually saddle-shaped or canoe-shaped, or long and narrow, lower than the petiolar groove and nearly as long as the petiole.

1b. Petiolar glands dome-shaped, volcano-shaped, or columnar, rarely absent.

2a. Petiolar glands long and narrow, lower than the petiolar grooves and nearly as long as the petiole ...... ...................................... 4. A. cookii

2 b. Petiolar glands saddle-shaped or canoe-shaped.

3a. Spines with two longitudinal flanges; leaflets more than 10 mm (usually 12-18 mm) long ...... ...................................... 10. A. mayana

3b. Spines lacking longitudinal flanges; leaflets less than 10 mm long.

4a. Leaflets with 2-3 veins from the base, lateral veins obvious; inflorescence more than 3 times longer than wide.......5. A. cornigera

4b. Leaflets with one vein from the base, lateral veins not obvious; inflorescence subglobose, less than 2 times longer than wide ................................................................................................................ 13. A. sphaerocephala

5a. Inflorescence cylindrical, more than 5 times longer than wide.

5b. Inflorescence globose, never more than 2 times longer than wide.

6a. Leaflets with one vein from the base, lateral veins not obvious; enlarged stipular spines flattened at the base........8. A. hindsii

6b. Leaflets with 2-5 veins from the base, lateral veins obvious; enlarged stipular spines terete or oval in cross section.

7a. Petiolar glands usually solitary; rachis glands scattered along leaf rachis........................6. A. gentlei

7b. Petiolar glands 3-5; rachis glands absent..................................................................................................3. A. collinsii

8a. Leaflets more than 1.8 mm wide, with 2-3 veins from the base, lateral veins obvious .... 1. A. allenii

8b. Leaflets mostly less than 1.8 mm wide, with one vein from the base, lateral veins not obvious.

9a. Adaxial surface of the petiole flattened (on well-developed leaves) with numerous petiolar glands (6-30) present on the flattened surface..............................................................................11. A. melanoceras

9b. Adaxial surface of the petiole grooved with fewer than 13 petiolar glands present in the groove.

10a. Stipular spines asymmetrical, commonly curved around the stem, pubescent with yellowish hairs ..................................................................................................................................... 9. A. janzenii

10b. Stipular spines symmetrical, glabrous to puberulent.

11a. Rachis glands cylindrical and narrowing toward the base; most stipular spines not enlarged, those that are usually not inhabited by acacia-ants........12. A. ruddiae

11b. Rachis glands narrowly volcano-shaped, or columnar and not narrowing toward the base; most stipular spines enlarged and inhabited by acacia-ants.

12a. Petiolar and rachis glands columnar; inflorescences in clusters of 10-40; fruit margins ridged.................................................................. 2. A. chiapensis

12b. Petiolar and rachis glands narrowly volcano-shaped; inflorescences in clusters of 4-8; fruit margins not ridged.................................................7. A. globulifera