Herbs, annual; taproot tapered, soft or ± woody. Stems erect to decumbent-ascending, sparingly to profusely branched throughout, 2-8(-15) dm, usually minutely puberulent, often also with long, spreading hairs, occasionally also glandular basally, glabrous distally. Leaves mostly in basal ¹/2; larger leaves with petiole 5-30 mm, blade lanceolate, ovate, oval, deltate-ovate, or narrowly deltate, 10-50 × 6-32 mm (distal leaves usually shorter, proportionately narrower), adaxial surface usually glabrous, sometimes sparsely hirtellous, abaxial surface paler than adaxial, usually glabrous, sometimes sparsely puberulent or with few coarse hairs, usually neither surface punctate, base acute, obtuse, or round, margins sinuate, often crisped, apex acute, obtuse, or rounded. Inflorescences terminal and axillary, forked ca. 2-5 times unevenly, usually with sticky internodal bands; branches strongly ascending, terminating in spicate or racemose flower clusters, axis 15-60 mm. Flowers: pedicel 0.1-1.6 mm; bracts at base of perianth soon deciduous, 1-2, usually lanceolate, lance-acuminate, or linear-lanceolate, rarely ovate, 0.4-1 mm; perianth white to pale pink, campanulate distal to constriction, 0.7-2 mm; stamens (1-)2-3(-4), included or slightly exserted. Fruits 4-20(-22) per cluster, remotely spaced or overlapped by 1-100% of their length, or 2-4 in group, separated by small gap from next group and with distal spikelets overlapping, straw colored to pale red-brown, narrowly obovoid to narrowly obpyramidal, 2-3.2(-3.6) × 0.9-1.1(-1.4) mm (l/w: [1.9-]2.1-3.1[-3.3]), apex rounded to bluntly conic-truncate, or truncate, glabrous; ribs 5, obtuse or round-obtuse, often with sharp ridges, slightly rugose near sulci; sulci 0.1-0.3 times as wide as base of ribs, smooth or slightly rugose, not papillate.

Duration: Annual

Nativity: Native

Lifeform: Unknown

General: Slender annual, usually with many branches spreading from base, more or less pubescent and sometimes a little ciliate below, not conspicuously glandular, sometimes with viscid bands.

Leaves: Opposite, ovate to ovate-deltoid, 1.5-5 cm long, obtuse, often rounded at apex, mostly truncate at base, margin entire or sinuate, upper leaves smaller , lanceolate to ovate-lanceolate.

Flowers: Cymose-paniculate, much branched, flowers in loose, slender, interrupted spikes; minute bracts, lanceolate-ovate, usually brown-punctate; perianth 1-1.5 mm long, white or pale pink, stamens 1-3, included or short-exserted.

Fruits: Anthocarp narrowly obovoid, 2.5-3 mm long, 5 angled, ridges broad, smooth, obtuse, groove closed or nearly closed, rugulose.

Ecology: Found on sandy soil from 500-5,000 ft (152-1524 m); flowers August-October.

Distribution: s CA, AZ, s NM; south to s MEX.

Notes: One of the most common Boerhavia species in Arizona. Distinguished by being an annual with pink flowers in elongate racemes (as opposed to cymes in intermedia and erecta) and not crowded but widely spaced ( broad-ridged, 5-angled fruits (4 angled in wrightii) with nearly closed furrows, these scarsely to not transverse-rugose (the opposite in torreyana).

Ethnobotany: Unknown

Etymology: Boerhavia is for Hermann Boerhaave (1663-1738) a Dutch botanist, coulteri is named for Dr. Thomas Coulter (1793-1843) an Irish botanist.

Synonyms: Senkenbergia coulteri

Editor: SBuckley 2010, FSCoburn 2015