Boerhavia coulteri var. palmeri

(S. Watson) Spellenberg
Sida 20: 153. 2002.
Basionym: Boerhavia spicata var. palmeri S. Watson Proc. Amer. Acad. Arts 24: 70. 1889 (as Boerhaavia)
Treatment appears in FNA Volume 4. Treatment on page 28. Mentioned on page 27.

Stems 2–7(–15) dm. Leaf blades 15–40 × 10–30 mm. Flowers: pedicel 0.1–1.1 mm; bracts at base of perianth usually 1; perianth 0.7–1 mm distal to constriction; stamens (1–)2, included or barely exserted. Inflorescences terminal clusters, axis 15–55 mm. Fruits 4–17 per cluster, usually remotely spaced, overlapped 1–50% (sometimes more) of their lengths, occasionally ± paired (rarely in 3s), straw colored to pale red-brown, narrowly obovoid, 2–2.4+ × 0.8–1.1 mm (l/w: [1.9–]2.1–3), apex rounded; ribs obtuse or rounded-obtuse, at most slightly rugose near sulci; sulci 0.1–0.3 times as wide as base of ribs, smooth.


Phenology: Flowering mid summer–early fall.
Habitat: Sandy or rocky soils in deserts or arid grasslands
Elevation: [0-]300-1200 m

Distribution

V4 43-distribution-map.gif

Ariz., Calif., N.Mex., Tex., Mexico (Baja California, Baja California Sur, Sonora).

Discussion

Boerhavia coulteri var. palmeri is a desert taxon primarily from south of the Mogollon Rim; its occurrence in southern New Mexico and western Texas, and on the Channel Islands, is perhaps the result of introductions. It seems very closely related to B. torreyana, distinguished by the less rugose ribs and narrower, nonpapillate sulci. The two may intergrade in southeastern Arizona. For decades var. palmeri has been included without taxonomic recognition within a broadly constructed B. coulteri. The latter is usually a more robust taxon with densely fruited inflorescences and more or less truncate fruits. The two are often sympatric, either in mixed populations, or with B. coulteri var. palmeri inhabiting nearby slightly drier sites. Though most specimens are easily placed into one variety or the other, the two intergrade and hybridization is likely.

Selected References

None.

Lower Taxa

None.

Richard W. Spellenberg +
(S. Watson) Spellenberg +
Boerhavia spicata var. palmeri +
Ariz. +, Calif. +, N.Mex. +, Tex. +, Mexico (Baja California +, Baja California Sur +  and Sonora). +
[0-]300-1200 m +
Sandy or rocky soils in deserts or arid grasslands +
Flowering mid summer–early fall. +
Weedy +  and Illustrated +
Boerhavia coulteri var. palmeri +
Boerhavia coulteri +
variety +