Coursetia glandulosa

Shrubs or trees, 1–10 m. Leaves even-pinnate, (3–)4.5–15 cm; stipules subulate, 5–8 × 1 mm; petiole 0.5–2 cm, strigose; rachis canaliculate; leaflets 8–22, petiolules 1 mm, glabrate, blades narrowly to widely elliptic, (3–)5–17[–50] × 3–7[–22] mm, base rounded, apex rounded, usually mucronate, surfaces glabrate to strigose. Racemes often from short shoots of older twigs, nodes often 20–40, internodes usually 1–5 mm, axis sparsely to densely stipitate-glandular; bracts caducous, ovate to lanceolate, 1–3.5 × 1 mm. Pedicels 3–10(–12) mm. Flowers: calyx tube (2.5–)3–4 mm, stipitate-glandular, lobes 2–5 mm, abaxial longer than laterals, adaxial connate, more so than laterals; corolla mostly whitish, 12–15 mm; filaments subequal. Legumes light to dark brownish, 25–110 × 5–7 mm, base blunt, dorsiventrally constricted between seeds, without linear transverse impressions between seeds on lateral surfaces, apex acute, often terminating in persistent style base, glandular. Seeds 1–13. 2n = 16.

Phenology: Flowering spring–early summer.
Habitat: Open, dry shrubby sites, seasonally dry woodlands.
Elevation: 0–1800 m.

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Ariz., Mexico.

Discussion

In the flora area, Coursetia glandulosa is known from Gila, Maricopa, Pima, Pinal, Yavapai, and Yuma counties.

The range of variation in Coursetia glandulosa tends toward the larger end in the Pacific coastal dry forests of western to southern Mexico and the smaller end in Arizona. This variation, especially in leaflet size and plant height, is clinal. The long stems of C. glandulosa can bend to small angles without breaking and thus have been used by the Seri tribe for harpoon shafts, bows, and other tools (R. S. Felger and M. B. Moser 1985). The conspicuous, dark reddish, gummy resin found on the stems of C. glandulosa from throughout its range is the result of a symbiotic relationship between ants and the larvae of a scale insect. This lac exudate is highly prized by the Seri (Felger and Moser).

Selected References

None.

Lower Taxa