Boerhavia spicata Choisy

C. F. Reed (1969) and subsequent authors have included one or more of Boerhavia coulteri, B. torreyana, and B. watsoni as synonymous with B. spicata. Even when those taxa are removed, B. spicata remains a variable species, widespread at low to middle elevations in southwestern North America, and distinguished by its mostly overlapping, obovoid fruits with rather open sulci, and the glandular pubescence on basal parts of the plant.

Boerhavia torreyana occurs in the Chihuahuan Desert, extends north of the Mogollon Rim in arid sites, and barely enters southeastern Arizona. The slender, remotely flowered inflorescences and the papillate sulci distinguish this from other spicate species. There were fewer ants and aphids on plants of B. torreyana (reported as B. spicata) with intact internodal bands as compared to those whose bands had been experimentally altered (Y. McClelan and W. J. Boecklen 1993).

Herbs, annual; taproot tapered, soft or ± woody. Stems erect or ascending, sparingly branched throughout, 30-70 dm, densely glandular-villous, or glandular-puberulent, with spreading, nonglandular hairs basally, glabrous distally. Leaves mostly in basal ¹/2; larger leaves with petiole 10-30 mm, blade oval, oblong, ovate, or ± triangular, 18-45 × 13-30 mm (distal leaves usually smaller, sometimes longer, proportionately narrower), adaxial surface lightly to densely glandular-pubescent, abaxial surface paler than adaxial, lightly to densely glandular-pubescent, neither surface punctate or both minutely punctate with clusters of brown cells, base truncate, round, or obtuse, margins sinuate, sometimes crisped, apex round to obtuse, rarely acute. Inflorescences terminal and axillary, branched 1-4 times unequally, with sticky internodal bands; branches strongly ascending, terminating in spicate or racemose flower clusters, axis 10-55 mm. Flowers: pedicel 0.4-2.3[-3.7] mm; bracts at base of perianth usually soon deciduous, usually 2, narrowly to broadly lanceolate, 0.7-1.8 mm, apex often acuminate; perianth white to pale pink, campanulate distal to constriction, 1-1.3 mm; stamens (2-)3, slightly exserted or included. Fruits 5-33 per cluster, usually overlapping or 2-4 in group separated by small gap from next group, straw colored to grayish or reddish tan, broadly obovoid, 1.9-2.4(-2.8) × 1.1-1.3 mm (l/w: 1.7-2.1[-2.3]), apex rounded, glabrous; ribs 5, obtuse-rounded to obtuse, often with low winglike ridge, slightly rugose near sulci; sulci (0.2-)0.5 times as wide as base of ribs, slightly rugose, not papillate. 2n = ca. 52.

Herbs, annual; taproot tapered, soft or ± woody. Stems prostrate or decumbent-ascending, usually profusely branched throughout, 10-80 dm, minutely puberulent with flat hairs, usually also with spreading hairs, sometimes also glandular basally, glabrous distally. Leaves mostly in basal ¹/2; larger leaves with petiole 7-20 mm, blade oblong-ovate, oval, ovate, or lanceolate, 20-45 × 9-25 mm (distal leaves usually shorter, proportionately narrower), adaxial surface glabrous or sparsely and minutely puberulent, abaxial surface paler than adaxial, glabrous or minutely puberulent, sometimes glandular, neither surface punctate or both punctate with minute clusters of brown cells, base truncate, rounded, or obtuse, margins sinuate to sinuate-crisped, apex round to obtuse or acute. Inflorescences terminal and axillary, forked ca. 3-6 times unequally, diffuse, usually with sticky internodal bands; branches strongly ascending, terminating in spicate or racemose flower clusters, axis 10-40 mm. Flowers: pedicel 0.1-1.7 mm; bract at base of perianth usually soon deciduous, usually 1, broadly lanceolate to lance-attenuate, 0.5-1.2 mm; perianth whitish to purplish pink, campanulate distal to constriction, 1-1.3 mm; stamens 2, slightly exserted. Fruits 2-12 per cluster, usually remotely spaced, sometimes about ¹/2 overlapped, occasionally ± paired, straw colored to grayish tan, narrowly obovoid, 2.2-3(-3.8) × 0.9-1.1 (-1.3) mm (l/w: [1.9-]2.2-3.1), apex round or round-obtuse, glabrous; ribs 5, obtuse or round-obtuse, strongly rugose near sulci; sulci 0.5-1 times as wide as base of ribs, not or slightly rugose, papillate. 2n = 52.

Ariz., N.Mex., Tex.; Mexico.

Ariz., N.Mex., Tex., Utah; Mexico (Chihuahua, Coahuila); South America (introduced in Argentina).

Flowering late summer-early fall.

Flowering mid summer and early fall.

Sandy or rocky soils in open, arid grasslands, among open shrubs or mesquite and acacia woodlands [tropical deciduous forests]; [100-]700-1800m.

Sandy or rocky soils in deserts or arid grasslands; 600-1300m.

Boerhavia spicata Choisy var. torreyana S. Watson, Proc. Amer. Acad. Arts 24: 70. 1889 (as Boerhaavia)