9.
Boerhavia triquetra
S. Watson, Proc. Amer. Acad. Arts. 24: 69. 1889 (as Boerhaavia).
Herbs,
annual; taproot tapered, soft or ± woody.
Stems
erect or ascending, occasionally decumbent, moderately or profusely branched, primarily distally, 1-5 dm, minutely puberulent with bent hairs basally, glabrous or minutely puberulent distally.
Leaves
mostly in basal
1
/2 of plant; larger leaves with petiole 4-8[-15] mm, blade broadly ovate or oval to lanceolate, 10-21[-35] × 6-8[-13] mm (distal leaves smaller, proportionately narrower), adaxial surface usually glabrous, rarely minutely puberulent, abaxial surface paler than adaxial, glabrous, neither surface punctate, base round [obtuse], margins shallowly sinuate, apex acute, obtuse, or round.
Inflorescences
terminal or axillary, forked ca. 3-6 times ± evenly (or clearly unevenly), diffuse, with sticky internodal bands; branches usually terminating in umbels or flowers borne singly, usually well beyond leaves.
Flowers:
pedicel 0.3-4.5 mm; bracts at base of perianth quickly deciduous, 2, linear-lanceolate to lanceolate [ovate], 0.5-0.6 mm; perianth whitish to pale pink or purplish, campanulate beyond constriction, 1 mm; stamens 2-3, included or barely exserted.
Fruits
1-7 per umbel, straw colored or gray-brown, obpyramidal, 2.5-3.1 × 1.3-1.9 mm (l/w: 1.6-2.1), base stipelike, apex round-truncate, glabrous; ribs 3-4(-5), acute or winglike, tapering to pedicel, slightly rugose or undulate near sulci; sulci 0.5-1 times as wide as base of ribs, coarsely transversely rugose, smooth or very faintly papillate.
Flowering summer-late fall. Sandy or gravelly areas in deserts; [0-]100-300 m; Ariz., Calif.; Mexico (Baja California, Baja California Sur, Sonora).
Boerhavia triquetra
, very narrowly defined here by a predominance of 3- and 4-ribbed fruits, is uncommon in the flora, known to occur only on low deserts near the Colorado River and southward around the Sea of Cortez. The species has few- or 1-flowered terminal inflorescences. Its relationship to, and distinctness from,
B.
intermedia
, needs clarification. In the area of the type locality, Bahia de los Angeles, on the east coast of Baja California, some plants have only 3- and 4-winged fruits, whereas most will have 3-, 4-, and some 5-winged fruits. The five-winged fruits do not differ from those of
B. intermedia
, a species common on the peninsula. Intergradient plants occur on the peninsula and on islands in the gulf.
