Trifolium vesiculosum |
Trifolium siskiyouense |
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arrow-leaf clover |
Siskiyou clover |
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Habit | Herbs annual, 15–70 cm, glabrous. | Herbs perennial, 20–50 cm, glabrous; rhizomes elongate, slender, roots tuberous. |
Stems | erect or ascending, branched. |
erect, sparsely branched. |
Leaves | palmate; stipules linear-lanceolate, 1–3.5 cm, margins entire, apex subulate or setaceous; petiole 0.5–10 cm; petiolules 1 mm; leaflet 3, blades obovate to oblong, elliptic or lanceolate, 0.5–4 × 0.5–1.5 cm, base cuneate, veins prominent, thickened, margins spinulose-denticulate, apex apiculate, surfaces glabrous. |
palmate; stipules lanceolate, 0.8–1.5 cm, margins entire or slightly lacerate, apex acuminate; petiole 1.6–2.4 cm; petiolules 0.5 mm; leaflets 3, blades obovate, oblanceolate, or elliptic, 0.8–3 × 0.5–0.7 cm, base cuneate, veins fine or thickened distally, margins finely serrulate, apex acute, mucronate, or retuse, surfaces glabrous. |
Inflorescences | terminal or axillary, 50–100+-flowered, globose, ovoid, or oblong, 3–6 × 2–3.5 cm; involucres absent. |
usually terminal, sometimes axillary, 30–50-flowered, subglobose, 1.2–1.8 × 1.5–2 cm; involucres shallowly bowl-shaped, 18–22 mm, deeply incised, lobes slender, irregular or bifurcate. |
Peduncles | 1–12 cm. |
2.8–3.4 cm. |
Pedicels | absent; bracteoles lanceolate, 6–7 mm, acuminate. |
straight, 0.5–0.8 mm; bracteoles linear, 1–2 mm. |
Flowers | 12–16 mm; calyx urceolate, not bilabiate, inflated in fruit, 6–10 mm, glabrous, veins 20–36, connected by transverse veins in fruit, tube 3–5 mm, lobes reflexed, subequal, subulate, as long as tube, orifice constricted; corolla white becoming pink, 12–15 mm, banner ovate, broadly clawed, striate, 12–15 × 2–4 mm, apex acute-acuminate. |
10–13 mm; calyx tubular, 0.5–0.6 mm, glabrous, veins 10, tube 2 mm, lobes ± equal, 3–4 mm, orifice open; corolla white to purple, 9–12 mm, banner oblong, 7–12 × 2–3 mm, apex retuse. |
Legumes | ellipsoid, 2.5–2.5 mm, shorter than calyx. |
oblong, 2–4 mm. |
Seeds | 2 or 3, brown, ovoid, 1–1.5 mm, roughened. |
2–4, brown, subglobose or mitten-shaped, 1.5 mm, smooth. |
2n | = 16. |
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Trifolium vesiculosum |
Trifolium siskiyouense |
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Phenology | Flowering Apr–Jul. | Flowering Jun–Jul. |
Habitat | Fields, roadsides, forest openings. | Wet meadows, grassy hillsides. |
Elevation | 0–1000 m. (0–3300 ft.) | 1000–1500 m. (3300–4900 ft.) |
Distribution |
AL; AR; CA; FL; GA; LA; MA; MO; MS; OK; OR; SC; TX; VA; WA; s Europe; e Europe; w Asia [Introduced in North America]
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CA; OR |
Discussion | Trifolium vesiculosum was first introduced into cultivation in the United States in 1963 and is grown in southern and western states (J. D. Miller and H. D. Wells 1985). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Trifolium siskiyouense is known from Shasta and Siskiyou counties, California, and Douglas, Jackson, and Josephine counties, Oregon. It is difficult to distinguish from T. wormskioldii without underground parts showing the tubers, but can be separated from the latter by deeply cut involucral segments, long-lobed, slender calyces, and the combination of long wing petals and short keel petals (J. M. Gillett 1980). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 11. | FNA vol. 11. |
Parent taxa | Fabaceae > subfam. Faboideae > Trifolium | Fabaceae > subfam. Faboideae > Trifolium |
Sibling taxa | ||
Synonyms | T. wormskioldii var. siskiyouense | |
Name authority | Savi: Fl. Pis. 2: 165. (1798) — (as vessiculosum) | J. M. Gillett: Canad. J. Bot. 58: 1441. (1980) |
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