Boerhavia erecta L., erect spiderling. Annual, taprooted, not rosetted, several–stemmed at base, principal branches spreading to ascending, in range to 75 cm tall; shoots with only cauline leaves, at each node with pair of leaves unequal (anisophyllous) and producing a pair of unequal axes, shoots mostly horizontally oriented (± plagiotropic), puberulent and with scattered longer hairs, foliage distinctly bicolor being green on upper surface and pale gray–green on lower surface, glandular–hairy but not viscid.
Stems cylindric, to 5 mm diameter (internodes) and swollen at nodes, tough, internodes to 130 mm long, green with whitish streaks (raphides in tissue), lacking periderm.
Leaves opposite decussate, simple, petiolate, without stipules; petiole channeled, 6—40 mm long, often tinged pinkish to purplish, puberulent with nonglandular and glandular hairs; blade symmetric, ovate to lanceolate or rhombate–ovate, 20—85 × 13—65 mm, at each node 1 blade ca. 2× other blade, subtruncate to broadly tapered at base, subentire, wavy, and purplish on margins, acute to acuminate at tip, pinnately veined with principal veins sunken on upper surface and raised on lower surface, upper surface aging with scattered short hairs having swollen bases and sometimes a purplish midrib, lower surface gray, mostly glabrate, and somewhat reflective with the most visible hairs along veins.
Inflorescence cymelike, on a reproductive structure forked several times, on ultimate branchlets with 1(—3) flowers; at each node along a principal shoot having 2 or 3 unequal axes, axis of reproductive unit swollen at base, at the lowest node the principal axis to 80 mm long decreasing upward; bracts subtending axis at fork 2 per node, < 180°, fused across 1 side and forming short ledge on other side to the base of the smaller axis, unequal, narrowly acuminate, 2.5—5.5 mm long decreasing upward, the longer subtending the thicker axis, keeled at the lowest node, sometimes purplish red above midblade or on margins; involucre of bracts or bractlets subtending clusters of flowers absent; bractlets and bracteoles subtending sessile flower 1—3, lanceolate to linear–lanceolate, 0.8—1.2 mm long, short–ciliate on margins, persistent.
Flower bisexual, radial, ca. 2 mm across; perianth (calyx) mostly 10–lobed, with green, 5–ribbed tube around ovary and funnel–shaped above; lobes spreading, acute–triangular, 0.3—0.5 × 0.3—0.4 mm; stamens typically 3, free; filaments 1.4—1.7 mm long, pale pink, never straight; anthers dorsifixed, conspicuously dithecal, short–exserted, 0.3—0.35 mm long, cream–colored to greenish, longitudinally dehiscent; pollen cream–colored to whitish; pistil 1; ovary superior (appearing inferior), obovoid, ± 0.4 × 0.25 mm, light green, smooth, glabrous, 1–chambered with 1 basal ovule; style at level of anthers, to 1 mm long mm long, pink, flared and reddish at stigmatic tip.
Fruit diclesium, sessile to short–stalked, 1–seeded, club–shaped truncate at top, ca. 3 × 1.2 mm shorter if fruit solitary, 5–ribbed, the ribs somewhat bumpy, glabrous.
Seed ± 5–sided wedge–shaped, ca. 2 × 1 mm, white, weakly angled with shallow dimples on faces, truncate at top, with radicle formed on 1 side.
A. C. Gibson