Trifolium depauperatum
J. Bot. Agric. 4: 69, plate 32, fig. 2. 1814.
Herbs annual, 1–30 cm, glabrous. Stems erect or decumbent, branched. Leaves palmate; stipules sheathing proximally, ovate-oblong to lanceolate, 0.4–1.3 cm, margins entire or serrulate, apex short triangular-cuspidate; petiole 1–5 cm; petiolules to 1 mm; leaflets 3, blades lanceolate, linear, obovate, or oblanceolate, 0.4–2.5 × 0.1–0.7 cm, base cuneate, veins moderately thickened abaxially, margins entire, serrate, or pinnately lobed, apex rounded, truncate, acute, or retuse, surfaces glabrous. Peduncles 2–6 cm. Inflorescences axillary or terminal, 3–15-flowered, globose or depressed-globose, 0.5–1.5 × 0.5–1.5 cm; involucres flattened, 3–13 mm, ± distinct or incised 1/2 their length, lobes 5–7, linear to elliptic or irregular, or vestigial, reduced to narrow ring, apex rounded to broad and irregularly erose, not split. Pedicels straight, 0–0.5 mm; bracteoles absent. Flowers 3–10 mm; calyx campanulate, 2–5 mm, glabrous, veins 5, tube 1–2.5 mm, lobes unequal, triangular-lanceolate or subulate, orifice open; corolla white or pink, 3–11 mm, inflated in fruit, banner broadly ovate, 4–7 × 3–8 mm, apex rounded, broad, acute, or retuse. Legumes sessile or stipitate, ovoid, obovoid, or oblong, 2–4 mm. Seeds 1–6, gray or tan, mottled, mitten-shaped, 1.2–1.6 mm, irregularly bumpy. 2n = 16.
Distribution
w, c North America, nw Mexico, South America (Chile, Peru).
Discussion
Varieties 3 (3 in the flora).
The three varieties of Trifolium depauperatum are relatively easily distinguished by characteristics of the involucres and fruit stipes. Leaf morphology is not helpful in making the distinctions; in each variety, leaf margins can range from nearly entire or toothed or laciniate. In the phylogenetic treatment by N. W. Ellison et al. (2006), T. depauperatum is not allied with T. fucatum and other clovers with inflated corollas but rather with T. obtusiflorum, T. trichocalyx, and T. willdenovii (although with weak support).
Selected References
None.
Lower Taxa
Key
| 1 | Involucres reduced to narrow vestigial ring; inflorescences 1–1.5 cm diam.; flowers 7–10 mm; legumes ovoid, 3–4 mm, sessile. | Trifolium depauperatum var. depauperatum |
| 1 | Involucres with evident bracts; inflorescences 0.5–1 cm diam.; flowers 3–8 mm; legumes oblong, ovoid, or obovoid, 2–4 mm, sessile or stipes 0.5–1 mm. | > 2 |
| 2 | Involucral lobes broad, irregular, with broad, hyaline margins and reticulate veins; legumes oblong, 3–4 mm, ± sessile. | Trifolium depauperatum var. amplectens |
| 2 | Involucral lobes oblong, often with narrow hyaline margins and raised, parallel veins; legumes ovoid or obovoid, 2–3 mm, stipes 0.5–1 mm. | Trifolium depauperatum var. truncatum |