Boerhavia diffusa
Boerhavia gracillima
red spiderling, spreading hogweed
slim-stalk spiderling
decumbent, ascending, or erect, usually profusely branched throughout, 3–10 dm, glabrous or minutely pubescent basally, glabrous or sparsely pubescent distally.
decumbent to erect, usually profusely branched throughout, 2–15 dm, usually minutely pubescent, rarely glabrous basally, usually glabrous, rarely sparsely and minutely pubescent distally.
mostly in basal 1/2 of plant;
larger leaves with petiole 10–30 mm, blade broadly lanceolate, ovate, or broadly ovate, occasionally ± round, 20–60 × 15–50 mm (distal leaves smaller, often proportionally narrower), base truncate, broadly cuneate, round, or shallowly cordate, often oblique, margins sinuate, apex obtuse to round, abaxial surface paler than adaxial, glabrous or minutely puberulent, sometimes glandular, usually with few large multicellular hairs on veins, adaxial surface glabrous, rarely sparsely puberulent, neither surface punctate.
mostly in basal 1/2 of plant;
larger leaves with petiole 3–25 mm, blade broadly rhombic to elliptic-oblong, broadly to narrowly ovate, occasionally wider than long, 18–45 × 13–50 mm (distal leaves smaller, proportionately narrower), adaxial surface glabrous, abaxial surface much paler than adaxial surface, glabrous or with hairs on veins, neither surface punctate, base usually obtuse to round, sometimes shallowly cordate, margins entire or sinuate, often undulate, apex acute, obtuse, or round.
terminal, forked ca. 3–6 times ± equally, diffuse, occasionally with sticky internodal bands;
branches divergent, terminating in compact subumbellate or capitate, 2–5-flowered clusters.
axillary or terminal, forked ca. 6–8 times unequally, diffuse, without sticky internodal bands;
branches divergent, terminating in 1(–3) flowers.
pedicel shorter than 0.5 mm;
bract at base of perianth quickly deciduous, 1, lanceolate, 0.8–1 mm;
perianth purplish red to reddish pink or nearly white, campanulate beyond constriction, 1–1.5 mm;
stamens 2–3, included or barely exserted.
pedicel slender, 3–13 mm;
bracts at base of perianth quickly deciduous, 2–3, linear-lanceolate to broadly lanceolate, 0.3–1.5 mm, quickly deciduous;
perianth wine red to brick red, widely funnelform distal to constriction, 2–4.5 mm;
stamens (4–)5(–6), well exserted.
(1–)2–5(–9) per cluster, gray-brown to brown, obpyramidal, (3–)3.5–4.5 × 1–1.2 mm (l/w: 2.8–4.1), apex broadly conic, with sparse or moderately dense stipitate-glandular hairs on ribs, less densely pubescent or glabrous in sulci [rarely entirely glabrous];
ribs 5, round, smooth;
sulci ± 2–2.5 times as wide as base of ribs, not rugose, not papillate.
usually borne singly, gray-brown to brown, oblong-clavate, 2.8–4.2 × 1–1.5 mm (l/w: [2–]2.2–3.5[–3.8]), apex round to rounded-conic, minutely puberulent, sometimes minutely glandular, rarely glabrous;
ribs 5, rounded, smooth or slightly rugose near sulci;
sulci 1–2.5 times as wide as base of ribs, not rugose, smooth or minutely papillate.
= 26, 52, 54, 116.
Boerhavia diffusa
Boerhavia gracillima
Boerhavia diffusa belongs to a pantropical complex whose distribution, because of differing taxonomic treatments, is not precisely discernable. In North America, the West Indies, and elsewhere, the complex has been treated as having one (e.g., R. W. Long and O. Lakela 1971; R. P. Wunderlin 1998) or two species (E. A. Kellogg 1988; J. K. Small 1913c; P. C. Standley 1918; C. Whitehouse 1996). In the latter situation various binomials have been used. The abrupt bend in the ribs near the fruit apex, making a broadly conic apex, seems to be a useful character for distinguishing most B. diffusa. The shape of the apex, the sparse pubescence of the fruit, the few fruits in individual terminal clusters, and the open, ± leafless inflorescence may have led R. E. Woodson Jr. and H. J. Kidd (1961) to suspect hybridization of this complex with the annual B. erecta. Hybridization is plausible (R. Spellenberg 2000), but clearly intermediate plants are not known.
The leaves are sometimes used as a vegetable (C. Whitehouse 1996). Extracts from roots are used to prepare an expectorant, a diuretic, and a laxative, and in treating asthma (S. P. Ambasta 1986).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The phase Boerhavia gracillima subsp. decalvata from low elevations in the Big Bend region of Texas and adjacent Mexico differs from the remainder of B. gracillima in that it is usually erect or strongly ascending, has glabrous fruits, and has flowers with purple to brick red perianths; the flowers are also in the upper half of the size range for the species. It is highly local and completely intergradient with surrounding populations of B. gracillima in the strict sense. In fruit and flower features the phase resembles B. anisophylla; in its diffuse inflorescence with slender branches (0.15 mm diam. proximal to the flower versus 0.25 mm in B. anisophylla) and in its deciduous bracts it is more similar to B. gracillima. Some populations of B. gracillima also have glabrous fruits, and a local endemic in Durango, B. chrysantha Barneby, differs primarily in its yellow perianths similar in size to those of B. gracillima subsp. decalvata. The complex is in need of careful study.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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