Trifolium dubium |
Trifolium depauperatum |
|||||||||
---|---|---|---|---|---|---|---|---|---|---|
least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover |
balloon sack clover, cowbag clover, dwarf sack clover, poverty clover |
|||||||||
Habit | Herbs annual, 20–40 cm, glabrous or sparsely hairy. | Herbs annual, 1–30 cm, glabrous. | ||||||||
Stems | erect to prostrate, branched from base. |
erect or decumbent, 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 sheathing proximally, ovate-oblong to lanceolate, 0.4–1.3 cm, margins entire or serrulate, apex short triangular-cuspidate; petiole 1–5 cm; petiolules to 1 mm; leaflets 3, blades lanceolate, linear, obovate, or oblanceolate, 0.4–2.5 × 0.1–0.7 cm, base cuneate, veins moderately thickened abaxially, margins entire, serrate, or pinnately lobed, apex rounded, truncate, acute, or retuse, surfaces glabrous. |
||||||||
Inflorescences | axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm; involucres absent. |
axillary or terminal, 3–15-flowered, globose or depressed-globose, 0.5–1.5 × 0.5–1.5 cm; involucres flattened, 3–13 mm, ± distinct or incised 1/2 their length, lobes 5–7, linear to elliptic or irregular, or vestigial, reduced to narrow ring, apex rounded to broad and irregularly erose, not split. |
||||||||
Peduncles | 1–1.5 cm. |
2–6 cm. |
||||||||
Pedicels | reflexed, 0.2–0.5 mm; bracteoles a fringe of red setae. |
straight, 0–0.5 mm; bracteoles absent. |
||||||||
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. |
3–10 mm; calyx campanulate, 2–5 mm, glabrous, veins 5, tube 1–2.5 mm, lobes unequal, triangular-lanceolate or subulate, orifice open; corolla white or pink, 3–11 mm, inflated in fruit, banner broadly ovate, 4–7 × 3–8 mm, apex rounded, broad, acute, or retuse. |
||||||||
Legumes | stipitate, ellipsoid, 1.5–2 mm, short beaked. |
sessile or stipitate, ovoid, obovoid, or oblong, 2–4 mm. |
||||||||
Seeds | 1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy. |
1–6, gray or tan, mottled, mitten-shaped, 1.2–1.6 mm, irregularly bumpy. |
||||||||
2n | = 16, 28, 32. |
= 16. |
||||||||
Trifolium dubium |
Trifolium depauperatum |
|||||||||
Phenology | Flowering May–Oct. | |||||||||
Habitat | Disturbed ground, fields. | |||||||||
Elevation | 0–2300 m. (0–7500 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]
|
w North America; nw Mexico; c North America; South America (Chile, Peru)
|
||||||||
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.) |
Varieties 3 (3 in the flora). The three varieties of Trifolium depauperatum are relatively easily distinguished by characteristics of the involucres and fruit stipes. Leaf morphology is not helpful in making the distinctions; in each variety, leaf margins can range from nearly entire or toothed or laciniate. In the phylogenetic treatment by N. W. Ellison et al. (2006), T. depauperatum is not allied with T. fucatum and other clovers with inflated corollas but rather with T. obtusiflorum, T. trichocalyx, and T. willdenovii (although with weak support). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||||||
Key |
|
|||||||||
Source | FNA vol. 11. | FNA vol. 11. | ||||||||
Parent taxa | Fabaceae > subfam. Faboideae > Trifolium | Fabaceae > subfam. Faboideae > Trifolium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Chrysaspis dubia, T. minus | Lupinaster depauperatus | ||||||||
Name authority | Sibthorp: Fl. Oxon., 231. (1794) | Desvaux: J. Bot. Agric. 4: 69, plate 32, fig. 2. (1814) | ||||||||
Web links |
|
|