Trifolium dubium |
Trifolium lupinaster |
|
---|---|---|
least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
lupine clover |
|
Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs perennial, 15–50 cm, glabrous or curly-pilose. |
Stems | erect to prostrate, branched from base. |
erect, unbranched or branched distally. |
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 adnate entire length of petiole, sheathing, lanceolate-oblong, 0.8–1.3 cm, margins sharply and finely serrate, pilose, apex acute; petiole 0.5–0.7 cm; petiolules 0.5 mm; leaflets (3–)5(–9), blades elliptic to linear-elliptic, 1–4 × 0.3–1.4 cm, base cuneate, veins prominent, cartilagenous, ending in sharp, curved teeth, margins setaceous, apex acute to obtuse, surfaces glabrous except midrib abaxially. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
terminal or axillary, 10–30-flowered, hemispheric or globose, 1.7–2.3 × 2.7–3.3 cm; involucres oblique, to 0.5 mm, wavy to toothed. |
Peduncles | 1–1.5 cm. |
1–5 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
erect or horizontal, 1–3 mm; bracteoles broadly shell-shaped, sometimes connate into lobed ridge, to 0.5 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. |
11–17 mm; calyx campanulate, oblique, 6–9 mm, glabrous or sparsely hairy distally and along veins, veins 10, tube 3 mm, lobes subequal, pilose, abaxial slightly longer, subulate, orifice open; corolla white to rose-purple, 10–15 mm, banner rolled into open tube, arched upwards distally, 10–15 × 4–5 mm, apex broadly rounded or acute, apiculate. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
oblong, 6–8 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
3–6, dark brown or gray-brown, globose-reniform, 1.5–2 mm, slightly roughened, dull. |
2n | = 16, 28, 32. |
= 16, 32, 40, 48. |
Trifolium dubium |
Trifolium lupinaster |
|
Phenology | Flowering May–Oct. | Flowering Jun. |
Habitat | Disturbed ground, fields. | Forest glades, meadows. |
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]
|
AK; Asia (n China, Russia) [Introduced in North America] |
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.) |
Populations of Trifolium lupinaster in Alaska appear to have been introduced as a potential forage crop and spread from cultivation (D. F. Murray and H. F. Drury 1974). (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 | Lupinaster pentaphyllus, Pentaphyllon lupinaster |
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | Linnaeus: Sp. Pl. 2: 766. (1753) |
Web links |
|