Peteria scoparia
Smithsonian Contr. Knowl. 3(5): 50. 1852.
Herbs to 0.8 m. Leaves 4–5 cm; stipules subulate, 3–5 × 1 mm; leaflets 11–13, blades linear to narrowly elliptic, 3–6(–9) × 1–2(–9) mm, apex acute, surfaces glabrate to strigose; terminal pinna often reduced to spinose seta. Racemes loose, rarely with more than 1 flower reaching anthesis simultaneously, nodes 8–20, internodes (3–)5–35 mm; bracts 3–5 × 0.5–1 mm. Pedicels 3–8 mm. Flowers: calyx tube 5.5–7 mm, glabrate to strigose, lobes 2–4 mm; banner 14–16 mm. Fruits 35–50(–62) × 5–6 mm. 2n = 18.
Phenology: Flowering summer.
Habitat: Open, dry shrubby vegetation, shrub-grasslands.
Elevation: 1000–2000 m.
Distribution
Ariz., Colo., N.Mex., Tex., Mexico (Chihuahua, Coahuila).
Discussion
Peteria scoparia occurs in the Chihuahuan Desert, eastern Colorado Plateau, and intervening desert areas.
Peteria scoparia occasionally has even-pinnate leaves by the reduction of the terminal leaflet to a spine. Evenly pinnate leaves are also found in related legume genera including Olneya and Sesbania and in certain species of Coursetia and Poitea Ventenat; no spines are present in these genera. Peteria scoparia does not necessarily have early-deciduous leaflets. Specimens from southwestern Colorado and the northernmost populations in Arizona and New Mexico display more luxuriant foliage that approaches P. thompsoniae. Although these northernmost specimens of P. scoparia are vegetatively very similar to P. thompsoniae, they have inflorescences with widely spaced flowers, banners to 16 mm, and leaflets to 4 mm wide (M. Lavin and M. Sousa S. 1995).
Selected References
None.