Prosopis velutina Wooton

  • 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

    Prosopis velutina Wooton

  • Description

    Species Description - Usually armed, pubescent shrub or tree, 1-10 m. Leaves mostly clustered on heavy spurs, strongly petioled; pinnae 1-2(-3) pairs; leaflets 15-20 pairs, crowded, with intervals less than width of leaflets, elliptic-oblong, .6-1.3 cm, ca 3-5 r, moderately reticulate, often with marginal or submarginal nerves. Spines nodal, 1-2, mostly short, sometimes obsolescent. Flowers in yellow-green, ament-like spikes clustered 2-4 from spurs. Legume stipitate, linear, subterete, 1-2 dm long, ca 8 mm diam, beaked, shallowly torulose or not, the segments oblique, about as wide as long; valves initially puberulent and succulent, becoming woody; endocarp segmented around each seed as in P. glandulosa.

  • Discussion

    P. juliflora var. velutina (Wooton) Sarg. P. chilensis var. velutina (Wooton) Standi. Neltuma velutina (Wooton) Britt. & Rose CN 2n = 56 (Cherubini, 1954; as P. juliflora var. velutina). Prosopis velutina is the characteristic mesquite of the Arizona deserts. Its range abuts against that of P. glandulosa var. torreyana to the east, and to the west and northwest. While distinctive in ideal form (two pinnae; numerous, crowded, pubescent, short and broad leaflets), it grades peripherally into P. glandulosa (Isely, 1972; Benson, 1941; and Map 43), and considerable material, mostly intermediary in range is not “ideal” velutina. In practice, it would be pleasant to regard it as a variety of P. glandulosa but I have taken it up as a species on the basis of the historical interpretation presented by Johnston (1962). In simplistic summary, he postulates the independent evolution of P. velutina and its replacement of P. glandulosa in present Arizona and Mexican deserts. If this is so, introgression between P. velutina and glandulosa is relatively recent, and it is possible that a few specimens from central Arizona, which I have mapped as intermediate, are derived from the P. velutina gene pool. Or perhaps P. glandulosa var. torreyana has been introduced, and introgression is not wholly peripheral. Some west Texas material with attributes of P. velutina is assigned to this taxon by Benson (1941), and Turner (1959). They are not the P. velutina of Arizona, and I have treated them (Isely, 1972) as forms of P. glandulosa var. torreyana. Johnston (1962) attributes the situation, speculatively, to introgression of P. glandulosa and Mexican P. laevigata.

  • Distribution

    S Arizona and sporadically in s California (probably introductions). Creosote bush-cactus desert, sandy soil in washes, river bottoms, dry flats, canyons, dunes; locally common; moderately in cultivation. 500-5500 ft. (April) May-July (Oct.). Mesquite. Mexico.

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