Trifolium dubium |
Trifolium bolanderi |
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least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
Bolander's clover, parasol clover |
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Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs perennial, 15–30 cm, glabrous. |
Stems | erect to prostrate, branched from base. |
ascending, cespitose, branched. |
Leaves | pinnate; stipules ovate, 0.3–0.5 cm, margins entire, apex acute; petiole to 1.5 cm; lateral leaflet petiolules to 0.5 mm, terminal leaflet stalk 1–1.5 mm; leaflets 3, blades obovate to elliptic-lanceolate, 1–2 × 0.5–1.5 cm, base cuneate, lateral veins prominent, ± parallel, ascending, margins dentate distally, apex rounded or retuse, surfaces glabrous or sparsely hairy. |
palmate; stipules ovate or lanceolate, 0.6–1.5 cm, margins entire, apex acute; petiole 1–7 cm; petiolules to 1 mm; leaflets 3, blades obcordate, obovate, or elliptic, 1–1.9 × 0.5–1.1 cm, base cuneate, veins fine to slightly thickened, margins setose, apex obtuse, rounded, or emarginate, apiculate, surfaces glabrous. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
terminal, 12–30-flowered, ovoid, 1–2 × 1.5–3 cm, rachis prolonged beyond flowers, undivided or forked, often bearing sterile flower buds distally; involucres absent. |
Peduncles | 1–1.5 cm. |
slender, bent distally, just below flowers, 5–20 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
strongly reflexed, 1–1.2 mm; bracteoles minute, cuplike. |
Flowers | 2.8–3.5 mm; calyx campanulate, 1.5–2 mm, glabrous, veins 5, tube 0.8–1 mm, lobes unequal, longer than tube, adaxial 2 shorter, orifice open; corolla pale yellow becoming brown, 2.6–3.2 mm, not or slightly ribbed, banner persistent, spatulate, 2.6–3.2 × 2 mm, apex rounded to broadly acute. |
12–14 mm; calyx deep violet, campanulate, gibbous, 3–5 mm, glabrous, veins 5, tube 1.5–2 mm, lobes unequal, triangular-subulate, orifice open; corolla lavender to purplish, 11–12 mm, banner curved, oblanceolate, 10–12 × 3–4 mm, apex narrow, rounded, slightly emarginate. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
ellipsoid, 3–4 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1 or 2, brown, ellipsoid, 1.2–1.5 mm, smooth. |
2n | = 16, 28, 32. |
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Trifolium dubium |
Trifolium bolanderi |
|
Phenology | Flowering May–Oct. | Flowering Jun–Aug. |
Habitat | Disturbed ground, fields. | Meadows. |
Elevation | 0–2300 m. (0–7500 ft.) | 2000–2300 m. (6600–7500 ft.) |
Distribution |
AK; AL; AR; AZ; CA; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WA; WI; WV; WY; BC; NB; NS; ON; PE; QC; SPM; c Europe; s Europe; w Asia [Introduced in North America; introduced also in s South America, e Asia (e China), n, s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
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CA |
Discussion | Trifolium dubium is often confused with Medicago lupulina Linnaeus; the latter may be distinguished by its toothed stipules, deciduous corollas, and shiny, black fruits. Little hop clover may be the co-called shamrock of Irish folklore (E. C. Nelson 1991; P. S. Wyse Jackson 2014); other candidates include other species of Trifolium or species of Medicago or Oxalis. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Trifolium bolanderi is known from the Sierra Nevada in California and may be vulnerable to shifts in climate patterns. Genetic diversity of populations of the species (based on allozyme patterns) was found to be relatively high; two genetically distinct groups of populations are known (R. G. Denton 2002). (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 | Chrysaspis dubia, T. minus | |
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | A. Gray: Proc. Amer. Acad. Arts 7: 335. (1868) |
Web links |
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