Monographs Details:
Authority:
Isley, Duane. 1973. Leguminosae of the United States: I. Subfamily. Mimosoideae. Mem. New York Bot. Gard. 25 (1): 1-152.
Isley, Duane. 1973. Leguminosae of the United States: I. Subfamily. Mimosoideae. Mem. New York Bot. Gard. 25 (1): 1-152.
Family:
Mimosaceae
Mimosaceae
Description:
Species Description - Small, armed tree with gray to brown bark and puberulent twigs and leaf rachises. Leaves mostly fascicled, bipinnate, shortly petioled to subsessile; leafstalk glands present on petiole and between upper and sometimes all pinnae or rachis glands absent; pinnae 3-6 pairs; leaflets 15-20 pairs, shortly oblong, ca 4 mm long, 1 mm wide, glabrous, scarcely nerved. Spines stipular, straight, mostly 1-2 cm. Flowers in yellow heads 1-1.2 cm diam, on axillary, fascicled, 1-3 per node, medially bracteate peduncles. Legume stipitate, compressed but usually torulose, 8-12(15) cm long, 1-1.5 cm wide; indehiscent or essentially so; margins sinuate; valves thick, heavily coriaceous, densely tomentulose.
Species Description - Small, armed tree with gray to brown bark and puberulent twigs and leaf rachises. Leaves mostly fascicled, bipinnate, shortly petioled to subsessile; leafstalk glands present on petiole and between upper and sometimes all pinnae or rachis glands absent; pinnae 3-6 pairs; leaflets 15-20 pairs, shortly oblong, ca 4 mm long, 1 mm wide, glabrous, scarcely nerved. Spines stipular, straight, mostly 1-2 cm. Flowers in yellow heads 1-1.2 cm diam, on axillary, fascicled, 1-3 per node, medially bracteate peduncles. Legume stipitate, compressed but usually torulose, 8-12(15) cm long, 1-1.5 cm wide; indehiscent or essentially so; margins sinuate; valves thick, heavily coriaceous, densely tomentulose.
Discussion:
A. adansonii Guill. & Perrott. A. arabica (Lamark) Willdenow CN 2n = 44 (Sharma & Battacharyya, 1958); 2n = 52 (Atchison, 1948). Both as Acacia arabica. Acacia nilotica is an African complex highly variable in legume characters; the above description relates only to the material seen in the United States. Since the usual base chromosome number in Acacia is 13, and Atchison having found A. nilotica as a tetraploid at 52, the Sharma and Bhattacharyya count of 44 is of more than average interest. The cytological observations are illustrated and karyotype analysis presented. No voucher specimens are cited. The authors suggest that aneuploid phenomena may be responsible for the situation. Bailey and Bailey (1941) take up A. nilotica, and it is noted by Barrett (1956) among Florida cultivated trees. Specimens which I have seen (either herbarium or field) are of park or institutional plantings in southern Florida (Dade Co.). The credentials of A. nilotica for inclusion in this treatment thus are dubious and the same is true of A. seyal. They are taken up as examples of African species present as novelties in the United States. They have the general aspect of native kinds like A. jarnesiana, and A. smallii, but differ in their bracteate peduncles. Only A. constricta and A. neovernicosa among native species share the latter feature and these have considerably smaller heads.
A. adansonii Guill. & Perrott. A. arabica (Lamark) Willdenow CN 2n = 44 (Sharma & Battacharyya, 1958); 2n = 52 (Atchison, 1948). Both as Acacia arabica. Acacia nilotica is an African complex highly variable in legume characters; the above description relates only to the material seen in the United States. Since the usual base chromosome number in Acacia is 13, and Atchison having found A. nilotica as a tetraploid at 52, the Sharma and Bhattacharyya count of 44 is of more than average interest. The cytological observations are illustrated and karyotype analysis presented. No voucher specimens are cited. The authors suggest that aneuploid phenomena may be responsible for the situation. Bailey and Bailey (1941) take up A. nilotica, and it is noted by Barrett (1956) among Florida cultivated trees. Specimens which I have seen (either herbarium or field) are of park or institutional plantings in southern Florida (Dade Co.). The credentials of A. nilotica for inclusion in this treatment thus are dubious and the same is true of A. seyal. They are taken up as examples of African species present as novelties in the United States. They have the general aspect of native kinds like A. jarnesiana, and A. smallii, but differ in their bracteate peduncles. Only A. constricta and A. neovernicosa among native species share the latter feature and these have considerably smaller heads.
Distribution:
Africa|
Africa|