Acacia constricta Benth.

  • Authority

    Isley, Duane. 1973. Leguminosae of the United States: I. Subfamily. Mimosoideae. Mem. New York Bot. Gard. 25 (1): 1-152.

  • Family

    Mimosaceae

  • Scientific Name

    Acacia constricta Benth.

  • Description

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    Species Description - Spiny, glabrate or hirsutulous shrub or small tree, usually 1-3 m high and low-divergent without exserted branches, rarely larger tree. Leaves mostly from spurs, bipinnate; leafstalk axis 2-3.5 mm with glands between (or below) some or all pinnae or distal on petiole; pinnae (2-)4-6(-7) pairs; leaflets 6-14(-18) pairs, ovate to short-oblong (1.5-)2-3(-4) mm, thick, scarcely glutinous; venation indiscernible or midvein evident. Spines stipular, paired (infrequently absent), usually white, .5-2 (-4) cm. Flowers in bright yellow, fragrant heads, .6-.9 cm diam, 1-3 from leaf spurs; peduncles medially bracteate. Legume short-stipitate, linear, turgid-compressed, moniliform, 4-8 (-12) cm long, ca 5 mm diam, reddish, becoming brown, coriaceous, ultimately dehiscent.

  • Discussion

    Acaciopsis constricta (Benth.) Britt, and Rose CN 2n = 52 (Turner, 1959; Turner & Fearing, 1960a). Variance within this species is briefly discussed by Isely (1969). Since that time, I have noted that the foliage of Arizona forms is characteristically stiffly hirstulous, that of Texas specimens glabrate. New Mexico material is a mixture; thus the character seems to be clinal in nature. Although I characterize the species as usually of shrubby stature, I have seen a tree in Arizona whose trunk was ca 4 dm diam. Herbarium material of A. constricta, A. smallii and A. neovernicosa is frequently confounded. In the absence of fruit, A. constricta and A. neovernicosa are consistently marked by the bracteate peduncles and usually have smaller leaflets than A. smallii. A. constricta and A. neovernicosa are closely related, and some have preferred to treat the latter as A. constricta var. vernicosa Benson. Several workers have reported intermediacy between the two, and herbarium material is frequently confused. Turner and Fearing (1960a), however, note no evidence of hybridization in mixed populations and my field observations are confirmatory. Among numerous populations that I have examined, especially in southern New Mexico, some were entirely of one or the other species, others including both. In the latter instance, no intermediates were seen. As Turner and Fearing, I presume the difference in ploidy level serves as a compatibility barrier.

  • Distribution

    Trans-Pecos Texas to w Arizona (n to Yavapai Co.), introduced further east, and possibly in California. Rocky arid slopes, talus, floodplains and washes, canyons; with pinyon-juniper, creosote-grass, mesquite, local or abundant; infrequently in cultivation. Ca 2000-6500 ft. (April)May-Sept.(Nov.).

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