Trifolium dubium |
Trifolium macraei |
|
---|---|---|
least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
Chilean clover, Macrae's clover |
|
Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs annual, 3–30 cm, pubescent. |
Stems | erect to prostrate, branched from base. |
erect, ascending, or prostrate, 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 to oblong, 0.6–1 cm, margins entire, apex acuminate to cuspidate; petiole 0.5–6 cm; petiolules to 0.5 mm; leaflets 3, blades obovate, oblanceolate, or elliptic, 0.6–1.6 × 0.3–1.2 cm, base cuneate, veins obscure or slightly thickened, margins subentire to serrate, apex rounded, retuse, surfaces pubescent. |
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
terminal or subterminal, usually paired, sometimes one head slightly stalked, partially hidden by terminal leaves and stipules, 10–40-flowered, ovoid or subglobose, 0.8–2.5 × 0.5–2 cm; involucres absent, involucrelike structure formed from terminal leaves and stipules. |
Peduncles | 1–1.5 cm. |
0–0.2 cm. |
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
absent; bracteoles broadly ovate to linear, 1–2 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. |
5.5–7.5 mm; calyx tubular, 4–5 mm, pubescent, veins 5–10, tube 1.5–2 mm, lobes subequal, subulate, orifice open; corolla usually purple or pink, rarely white, 5–7 mm, banner obovate-oblong, 6–7 × 2–3 mm, apex rounded, slightly denticulate. |
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
oblong, 2.5–3 mm. |
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1, yellow, mottled, ellipsoid, 1.6–2 mm, smooth. |
2n | = 16, 28, 32. |
= 16. |
Trifolium dubium |
Trifolium macraei |
|
Phenology | Flowering May–Oct. | Flowering May–Jun. |
Habitat | Disturbed ground, fields. | Grassy fields, sandy ocean bluffs. |
Elevation | 0–2300 m. (0–7500 ft.) | 0–800 m. (0–2600 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]
|
CA; OR; South America (Chile)
|
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 macraei was described from specimens collected in Chile; the South American plants have broader banners, smaller auricles on the wing petals, and styles that are barely curved upwards distally (D. Isely 1998). Further examination of the disjunct populations may reveal other differences and prompt reconsideration of the identity of North American specimens. The record from Massachusetts is a waif. (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 | T. bicephalum, T. catalinae, T. mercedense, T. traskiae |
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | Hooker & Arnott: Bot. Misc. 3: 179. (1833) |
Web links |
|