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 - Spiny shrub or small, irregularly branched tree to 5 m. Pubescence hirsutulous, often abundant on new stems, leaf rachises and peduncles. Leaves bipinnate, alternate and clustered from spurs with peduncles; leafstalk 1.5-4 cm, channeled, usually narrowly so; petiole usually exceeding 5 mm, bearing a small circular gland which is often depressed in channel, another gland sometimes present between uppermost pinnae; pinnae 2-5(-6) pairs; leaflets 9-20 pairs, asymmetric-oblong, 4-5(-6) mm, with evident nervation or nerves rarely indistinct. Stipules spinose, variable in length, to 2.5 cm, rarely abortive. Flowers in fragrant, yellow to orange heads 1-1.3 cm diam on clustered, 1-2 (-4), stout, often arcuate, ebracteate peduncles from spurs, usually with leaves, (1-) 2—3 cm. Calyx ca 1.5 mm, obscurely lobed; corolla 2.2-2.3 mm, lobed about 1/6 of length. Legume persistent, sessile or substipitate, stoutly oblong, straight to slightly curved, turgid, scarcely or irregularly constricted, 4-7 cm long, ca 1 cm diam, acute to obtuse at apex but not beaked, septate between seeds, pulpy when immature, woody when fully ripe, tardily dehiscent or indehiscent; sutures conspicuous, white and brown margined; valve surface glabrous, becoming dark brown to black.
Species Description - Spiny shrub or small, irregularly branched tree to 5 m. Pubescence hirsutulous, often abundant on new stems, leaf rachises and peduncles. Leaves bipinnate, alternate and clustered from spurs with peduncles; leafstalk 1.5-4 cm, channeled, usually narrowly so; petiole usually exceeding 5 mm, bearing a small circular gland which is often depressed in channel, another gland sometimes present between uppermost pinnae; pinnae 2-5(-6) pairs; leaflets 9-20 pairs, asymmetric-oblong, 4-5(-6) mm, with evident nervation or nerves rarely indistinct. Stipules spinose, variable in length, to 2.5 cm, rarely abortive. Flowers in fragrant, yellow to orange heads 1-1.3 cm diam on clustered, 1-2 (-4), stout, often arcuate, ebracteate peduncles from spurs, usually with leaves, (1-) 2—3 cm. Calyx ca 1.5 mm, obscurely lobed; corolla 2.2-2.3 mm, lobed about 1/6 of length. Legume persistent, sessile or substipitate, stoutly oblong, straight to slightly curved, turgid, scarcely or irregularly constricted, 4-7 cm long, ca 1 cm diam, acute to obtuse at apex but not beaked, septate between seeds, pulpy when immature, woody when fully ripe, tardily dehiscent or indehiscent; sutures conspicuous, white and brown margined; valve surface glabrous, becoming dark brown to black.
Discussion:
Vachellia farnesiana (L.) Wight & Arn. CN 2n = 52 (Atchison, 1948; Sharma & Bhattacharyya, 1958). The interpretation of this species is that of Isely (1969). Most A. jarnesiana Hort. in cultivation, Texas and west is the more xeric A. smallii Isely. Acacia jarnesiana and A. smallii, widely disjunct as to natural ranges in the United States, are discussed on a comparative basis under the latter. Judged by origin of source material, the several chromosome number counts published for A. jarnesiana are probably of that species and not the related A. smallii. Atchison (1948) notes that A. jarnesiana is the only American tetraploid in contrast with usual African polyploidy. Her generalization that there is a contrast between diploidy in the Americas and polyploidy on the African continent is valid, but the specifics are a figment of insufficient sampling. For example, among U.S. species which now have been counted (and many remain to be examined cytologically), A. constricta is also a tetraploid, the condition certainly being derived independently of that of A. jarnesiana. Chromosome numbers of the close relatives of A. jarnesiana may prove taxonomically significant. For example, the South American A. cavenia (Molina) Hook. & Arn. is reported diploid (Atchison, 1948). Acacia smallii, of special interest here, is apparently yet to be examined.
Vachellia farnesiana (L.) Wight & Arn. CN 2n = 52 (Atchison, 1948; Sharma & Bhattacharyya, 1958). The interpretation of this species is that of Isely (1969). Most A. jarnesiana Hort. in cultivation, Texas and west is the more xeric A. smallii Isely. Acacia jarnesiana and A. smallii, widely disjunct as to natural ranges in the United States, are discussed on a comparative basis under the latter. Judged by origin of source material, the several chromosome number counts published for A. jarnesiana are probably of that species and not the related A. smallii. Atchison (1948) notes that A. jarnesiana is the only American tetraploid in contrast with usual African polyploidy. Her generalization that there is a contrast between diploidy in the Americas and polyploidy on the African continent is valid, but the specifics are a figment of insufficient sampling. For example, among U.S. species which now have been counted (and many remain to be examined cytologically), A. constricta is also a tetraploid, the condition certainly being derived independently of that of A. jarnesiana. Chromosome numbers of the close relatives of A. jarnesiana may prove taxonomically significant. For example, the South American A. cavenia (Molina) Hook. & Arn. is reported diploid (Atchison, 1948). Acacia smallii, of special interest here, is apparently yet to be examined.
Distribution:
United States of America North America| West Indies| Central America| Venezuela South America| Colombia South America| Guyana South America| Suriname South America| French Guiana South America| Brazil South America| Ecuador South America|
United States of America North America| West Indies| Central America| Venezuela South America| Colombia South America| Guyana South America| Suriname South America| French Guiana South America| Brazil South America| Ecuador South America|