Havardia mexicana

  • Title

    Havardia mexicana

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Havardia mexicana (Rose) Britton & Rose

  • Description

    5. Havardia mexicana (Rose) Britton & Rose, N. Amer. Fl. 23: 41. 1928. Pithecolobium mexicanum Rose, Contr. U.S. Natl. Herb. 1: 100. 1891. — "[Mexico. Sonora:] In the Alamos Mountain. March 26 to April 8 [1890, E. Palmer] No. 297." — Holotypus, US 46937!, isotypus, NY!, UC 84419!.

    Pithecollobium mexicanum sensu Standley, 1922: 397; Pithecellobium mexicanum sensu Wiggins, 1964: 590.

    Microphyllidious drought-deciduous trees attaining 10 m, with smooth, transversely lenticellate bark, erratically armed at nodes of new branchlets with a pair of small, stiffly ascending, subulate or acicular stipules and at those of annotinous branches with lignescent, sometimes longer, either ascending or spreading-decurved ones, the young growth finely pilosulous with more or less erect white hairs to 0.25-0.45 mm, the foliage pallidly gray-olivaceous, only a trifle paler beneath, the lfts commonly pubescent beneath only, but sometimes puberulent also above, and sometimes glabrous facially but ciliolate, the shortly racemose capituliform units of inflorescence arising 1-3 together at nodes of either efoliate, partly foliate, or hysteranthously foliate pseudoracemes lateral to the main axis of long-shoots. Stipules of young growth 0.5-2 mm, of older branches 1-4 mm, long-persistent. Lf-formula ii-v/7-11; lf-stks of primary lvs 1-4 cm, the petiole 4—16 mm, at middle 0.35-0.5 mm diam, the longer interpinnal segments 3-8 mm; a nectary, rarely 2, randomly situated near base of petiole, near midpetiole, or close below first pinna-pair, sessile, shallow-cupular thick-rimmed, 0.3-0.5 mm diam, in profile scarcely 0.2 mm tall, none at tip of pinna-rachises; pinnae a little decrescent proximally, the rachis of penultimate pair 9-19 mm, the longer interfoliolar segments 0.9-2 mm; lft-pulvinules 0.2-0.4 x 0.2-0.25 mm, not wrinkled; lfts decrescent proximally, less so distally, the blade linear-oblong to narrowly oblong-obovate from semicordate-auriculate base, obtuse or obtusely apiculate, those near midrachis 3.3-6.5 x 1.3-2.2 mm, (2-)2.4-3.9 times as long as wide; venation pinnate (sometimes a relatively strong anterior primary nerve almost as long as the first secondary one), the straight midrib only a trifle forwardly displaced from center, giving rise on each side to 2-4(-5) weak secondary nerves brochidodrome close within the plane margin, the whole venation immersed on upper face, finely prominulous beneath. Peduncles 4-16 mm; capitula (technically short racemes) subhemispherical 7-15- fld., the linear receptacle (1-)1.5-4.5 mm; bracts linear-oblanceolate, early deciduous; pedicels 1-3.1 mm, at middle 0.25-0.4 mm diam; fls homomorphic, 5-merous, the perianth pilosulous overall or the corolla only so beyond middle; calyx shallowly campanulate 1.3-1.8 x 1.4—1.8(-2) mm, faintly 5-nerved, the broadly 3-angular teeth 0.4-0.6 mm; corolla 3.2-4.4mm, the recurving lobes 1.5-2.3 x 0.8-1.1 mm; androecium 37-48-merous, 9-11 mm, the stemono- zone 0.4—0.6 mm, the tube 0.7-1.8 mm, lacking callosities at base within; ovary glabrous at anthesis (but puberulent after fertilization), the stipe ±0.3 mm, the body ±1.3 mm, conical at each end, not sulcate laterally; stigma scarcely dilated. Pods shortly stipitate, the body in profile broad-linear, straight, 6-10 x 1.7-2.5 cm, 7-8-seeded, the papery valves dull brown glabrous externally, pallid within; seeds 6-10 x 4.5-6.5 mm, the pleurogram 4-6 x 2.5-3 mm.

    In thorn forest below 200 m, apparently localized on the Pacific lowlands of Mexico in S Sonora and N Sinaloa, and on the Gulf slope of Baja California Sur, in lat. 23°30'-30°N. — Map 45. — Fl. II-IV. — Chino, palo chino.