Herbs, annual [slightly woody at base]; taproot tapered, soft or ± woody. Stems usually erect, sometimes decumbent, profusely branched primarily distally, 2-12 dm, minutely puberulent with bent hairs basally, usually glabrous, rarely sparsely puberulent distally. Leaves mostly in basal 1/2 of plant; larger leaves with petiole 6-40(-55) mm, blade broadly rhombic-ovate, triangular-ovate, ovate, oval, or lanceolate, 20-50(-80) × 10-45 mm (distal leaves smaller, proportionately narrower), adaxial surface usually glabrous, sometimes minutely puberulent, usually minutely punctate, abaxial surface slightly paler than adaxial, usually glabrous, sometimes minutely puberulent, usually punctate with small patches of small brown cells, base obtuse to round, margins entire or sinuate, apex usually acute, less often obtuse or rounded. Inflorescences terminal, forked ca. 4-6 times ± evenly, diffuse, usually with sticky internodal bands; branches strongly ascending, terminating in irregular umbellate or subracemose clusters of flowers, not all pedicels attaching at same point (flowers occasionally borne singly). Flowers: pedicel (0-)0.3-2.5(-5) mm; bracts at base of perianth deciduous, usually 2, narrowly to broadly lanceolate, 0.5-1 mm, apex often acuminate; perianth whitish, usually tinged with pink or purple [bright pink] between lobes and in tube, campanulate beyond constriction, 1-1.5 mm; stamens 2-4, slightly exserted. Fruits 1-11 per cluster, pale greenish to straw colored or tan, narrowly obconic, (2.7-)3-3.5[-4] × 1.2-1.5 mm (l/w: (2-)2.3-3.2), apex truncate or broadly low conic, glabrous; ribs 5, acute, slightly rugose adjacent to sulci; sulci 0.5-1 times as wide as base of ribs, slightly to prominently coarsely transverse rugose, not papillate.
Flowering early summer-mid fall. Disturbed areas, gardens, road and railroad rights-of-way, stream beds; 0-1700 m [probably much higher in tropics]; Ala., Ariz., Ark., Fla., Ga., La., Md., Miss., Mo., N.Mex., N.C., Okla., S.C., Tenn., Tex.; Mexico; West Indies; Central America; South America; widely introduced throughout the tropics and warm-temperate regions.
Boerhavia erecta occasionally forms mixed populations with B. intermedia without apparent intergradation. Rarely, some specimens seem to combine features of either species, particularly with regard to inflorescence structure. This is especially so in Sonora, Mexico, and in parts of the Sonoran Desert in Arizona. The two species bloom simultaneously and are visited by small insects. Given the presumed close relationship and weedy habitats of each, hybridization seems possible. Usually, the two species can be distinguished by the differences in fruit length, the appearance of a crownlike apex of the nearly mature fruits of B. erecta (apex of ridges slightly expanded, apex of fruit slightly conic), and the more precisely constructed terminal umbels of B. intermedia. Both species, particularly B. intermedia, may produce entire inflorescences with branches terminating in single flowers. R. E. Woodson Jr. and H. J. Kidd (1961) suggested that B. erecta hybridizes with the perennial B. diffusa.
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Coarse annual herbs, 30-100 cm tall; stems erect and branched throughout, the lower branches sometimes trailing along the ground and the upper branches ascending; herbage glabrous or nearly so. Leaves: Opposite, with one leaf from each pair noticably smaller than the other; blades 2-8 cm long, broadly ovate to lanceolate, usually with a pointed tip and smooth or slightly wavy margins; leaf surfaces glabrous, sometimes with moderately to densely glandular patches. Flowers: Pinkish or greenish-tinged, with small clusters of 2-6 flowers arranged in elongate panicles or racemes; sepals 5, fused into a bell-shape and appearing petal-like, 1-2 mm long, pinkish or greenish; petals absent. Fruits: Achenes brownish-green, 3-5 mm long, narrowly obpyramidal and narrowing toward the base, with 5 smooth longitudinal ridges. Ecology: Found in open places and disturbed areas, from 1,000-5,000 ft (305-1524 m); flowers July-August. Distribution: From AZ east to NC and south to FL; south to S. Amer.; found worldwide in the tropics. Notes: Distinguished by being an annual with pale pink flowers in small clusters which appear to be umbels with unequal pedicels, but upon closer inspection you can see that the branches don't come from the same point, as they do in the true umbels of B. intermedia. Widely distributed in the tropics, this species can be very erect and stand up to 1 m easily; it is often distinctive with the slight reddish outline of the leaf margins and the mis-matched leaf size. Ethnobotany: Used in India to treat stomach ailments and various conditions involving internal inflammation. Etymology: Boerhavia is named for Dutch botanist Hermann Boerhaave (1663-1738); erecta means upright. Synonyms: Boerhavia thornberi Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2017