Trifolium longipes
Fl. N. Amer. 1: 314. 1838.
Herbs perennial, 5–46 cm, slightly pilose. Stems erect or ascending, cespitose, unbranched to sparsely branched distally. Leaves palmate; stipules ovate to lanceolate, 1–5 cm, margins usually entire, sometimes slightly serrate proximally, apex acute or acuminate; petiole 1–13 cm; petiolules to 1 mm; leaflets 3, blades linear, lanceolate to elliptic, or oblong, cauline sometimes ovate, 0.8–6 × 0.2–1.6 cm, base cuneate, veins slightly to very thickened, arching, margins entire or serrate, apex acute, surfaces glabrous abaxially, usually appressed-pubescent adaxially. Peduncles 1–30 cm. Inflorescences terminal, 10–40-flowered, globose, ellipsoid, obconic, or subglobose, 1–3.5 × 1–3.2 cm; involucres absent. Pedicels erect or reflexed in fruit, 0.5–2 mm; bracteoles scalelike, 0.5 mm. Flowers 10–19 mm; calyx tubular, 4–10 mm, hairy or glabrous, veins 5–10, tube 2.5–3 mm, lobes unequal, linear, shorter than or to 6 times tube, orifice open; corolla white, cream, pink, lavender, or purple, sometimes pale with purple tips, 10–18 mm, petals not beaked except subsp. multipedunculatum, banner ovate to oblanceolate, 10–18 × 3–4 mm, apex usually not beaked, usually obtuse, acute, or acuminate, rarely emarginate; ovaries pubescent distally. Legumes oblong to ellipsoid, 4–5 mm. Seeds 1–4, dark brown, flattened globose, 2–3 mm, smooth.
Distribution
w United States.
Discussion
Subspecies 12 (12 in the flora).
Trifolium longipes encompasses a morphologically diverse and taxonomically difficult suite of populations. J. M. Gillett (1969) united T. longipes with T. rusbyi and differentiated ten subspecies, with T. neurophyllum recognized as distinct. M. Zohary and D. Heller (1984) maintained T. rusbyi (with seven subspecies, including subsp. neurophyllum) as distinct from T. longipes (with five subspecies). Analyses of molecular data support the union of T. longipes and T. rusbyi (N. W. Ellison et al. 2006).
Selected References
None.
Lower Taxa
Key
| 1 | Banner, wing, and, often, keel petals beaked. | Trifolium longipes subsp. multipedunculatum |
| 1 | Banner, wing, and keel petals without beaks, banner apex acute to attenuate. | > 2 |
| 2 | Pedicels erect or proximalmost horizontal or slightly reflexed in fruit. | > 3 |
| 3 | Herbs rhizomatous; roots not fusiform, sometimes thickened. | > 4 |
| 4 | Calyx lobes lax, usually slightly longer than tube length, tube veins not prominent; leaflet blades lanceolate, elliptic to oblong, or ovate. | Trifolium longipes subsp. hansenii |
| 4 | Calyx lobes often ± rigid, 6 times tube length, tube veins usually prominent; leaflet blades linear to elliptic-linear or broadly elliptic. | Trifolium longipes subsp. elmeri |
| 3 | Herbs not rhizomatous (stems ascending from crowns); roots thickened, often fusiform. | > 5 |
| 5 | Banner and wing apices slender-acuminate. | Trifolium longipes subsp. longipes |
| 5 | Banner and wing apices usually acute or obtuse, rarely emarginate. | > 6 |
| 6 | Calyces and distal ends of peduncles densely pilose; banner apex acute. | Trifolium longipes subsp. atrorubens |
| 6 | Calyces and distal ends of peduncles sparsely pilose or glabrous; banner apex usually broad, acute or obtuse, rarely emarginate. | Trifolium longipes subsp. pedunculatum |
| 2 | Pedicels (at least proximal ones, usually all), strongly reflexed in fruit. | > 7 |
| 7 | Herbs with thickened roots, often fusiform, with crown of buried stems. | Trifolium longipes subsp. pygmaeum |
| 7 | Herbs usually rhizomatous, if rarely with roots ± thickened, then with crown of rhizomes above thickened portion, or with slender taproots bearing a crown of wiry, pilose stems. | > 8 |
| 8 | Pedicels slender, 1.5–2 mm; herbs with slender taproots, bearing crown of wiry, pilose stems. | Trifolium longipes subsp. oreganum |
| 8 | Pedicels stout, to 1 mm; herbs rhizomatous. | > 9 |
| 9 | Inflorescences globose or ellipsoid; proximal pedicels more strongly reflexed than distal ones. | > 10 |
| 10 | Inflorescences 18–22-flowered, globose, 2.2–2.5 cm diam.; flowers 10–13 mm, corollas purple, sometimes tips white. | Trifolium longipes subsp. shastense |
| 10 | Inflorescences 28–32-flowered, ellipsoid, 3–3.2 cm diam.; flowers 14–16 mm, corollas lavender. | Trifolium longipes subsp. caurinum |
| 9 | Inflorescences hemispheric, obconic, or subglobose; all pedicels strongly reflexed. | > 11 |
| 11 | Calyces sparsely pilose or curly-pilose at sinuses, often glabrous proximally; corollas white, cream, or violet. | Trifolium longipes subsp. reflexum |
| 11 | Calyces white-villous, veins and lobes green; corollas purple-violet or lavender. | Trifolium longipes subsp. neurophyllum |