Trifolium dubium |
Trifolium tomentosum |
|
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least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
woolly clover |
|
Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs annual, 10–20 cm, glabrous or sparsely hairy. |
Stems | erect to prostrate, branched from base. |
prostrate, ascending, or erect, 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 triangular-lanceolate, 0.4–1.2 cm, margins entire, apex acute or acuminate; petiole 0.5–7 cm; petiolules to 1 mm; leaflets 3, blades obovate, obcordate, or elliptic, 0.4–1.5 × 0.3–1 cm, base cuneate, veins moderately prominent, margins denticulate, apex rounded or emarginate, surfaces sparsely hairy abaxially, glabrous adaxially. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
axillary, 10–20-flowered, subglobose, soon becoming globose, flowers resupinate, calyces densely white-woolly, compacted, inflated, 0.5–1.5 × 0.5–1.5 cm; involucres a narrow rim, 0.2 mm. |
Peduncles | 1–1.5 cm. |
0.5–1.5 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
slightly reflexed, to 0.5 mm; bracteoles cup-shaped, membranous, 0.2 mm. |
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. |
3–7 mm; calyx tubular, inflated in fruit, markedly asymmetric-bilabiate, 2–6 mm, woolly adaxially, veins 5–10, connected by lateral veins, tube 1.5–2.5 mm, 4–5 mm in fruit, lobes unequal, subulate, shorter than tube, adaxial spreading or curved, orifice open, abruptly constricted in fruit; corolla pink, 3–6 mm, banner ovate, 3–6 × 3–6 mm, apex emarginate to crenulate. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
ovoid to globose, 2–3 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1 or 2, yellow to brown, mottled, mitten-shaped, 0.9–1.1 mm, smooth, glossy. |
2n | = 16, 28, 32. |
= 16. |
Trifolium dubium |
Trifolium tomentosum |
|
Phenology | Flowering May–Oct. | Flowering Feb–Apr. |
Habitat | Disturbed ground, fields. | Sandy lawns, fields, meadows, roadsides, clay soils among vernal pools. |
Elevation | 0–2300 m. (0–7500 ft.) | 0–400 m. (0–1300 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; FL; MA; NC; SC; s Europe (Mediterranean); sw Asia; n Africa; Atlantic Islands (Azores) [Introduced in North America; introduced also in South America (Chile), s Africa, Pacific Islands (New Zealand), Australia]
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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 tomentosum is occasionally cultivated as a forage crop (F. J. Hermann 1953) and is becoming weedy in the flora area and in Australia (R. P. Randall 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) | Linnaeus: Sp. Pl. 2: 771. (1753) |
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