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enable glossary links

least hop clover, lesser hop clover, lesser hop trefoil, little hop clover, shamrock, small hop-clover, suckling clover

red clover

Habit Herbs annual, 20–40 cm, glabrous or sparsely hairy. Herbs perennial, 20–70 cm, pilose or glabrous.
Stems

erect to prostrate, branched from base.

erect, ascending, 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 broadly triangular, 1–2 cm, margins entire, sometimes ciliate, apex mucronate or setaceous;

petiole 1–9 cm;

petiolules 1 mm;

leaflets 3, blades elliptic to obovate, 1.5–5 × 0.7–1.5 cm, base cuneate, veins prominent, margins subentire, apex obtuse, acute, or retuse, surfaces appressed-pubescent.

Inflorescences

axillary or terminal, 5–20-flowered, ovoid or globose, 0.5–0.9 × 0.6 cm;

involucres absent.

terminal, solitary or paired, 75–100+-flowered, globose or ovoid, 1.2–7.7 × 0.7–2.2 cm;

involucres absent, involucrelike structures formed of stipules of distalmost leaves.

Peduncles

1–1.5 cm.

± 0 cm, subtended by stipules of distal leaves.

Pedicels

reflexed, 0.2–0.5 mm;

bracteoles a fringe of red setae.

straight, 0–1 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.

15–18 mm;

calyx tubular-campanulate, 8–11 mm, hairy, veins 10, tube 3–4 mm, lobes unequal, adaxial equaling tube, lateral and abaxial 2 times tube, orifice hairy, slightly closed;

corolla usually rose-purple, rarely pink or white, 13–18 mm, banner elliptic-ovate, 10–13 × 3–5 mm, apex narrowly rounded.

Legumes

stipitate, ellipsoid, 1.5–2 mm, short beaked.

oblong, leathery distally, transversely dehiscent, 3 mm.

Seeds

1, yellow or pale brown, ellipsoid, 0.9–1 mm, smooth, glossy.

1 or 2, yellow, yellow-brown, or purple, ovoid, 1.6–2 mm, smooth, dull.

2n

= 16, 28, 32.

= 14.

Trifolium dubium

Trifolium pratense

Phenology Flowering May–Oct. Flowering May–Sep.
Habitat Disturbed ground, fields. Fields, prairies, roadsides, disturbed areas.
Elevation 0–2300 m. (0–7500 ft.) 0–3100 m. (0–10200 ft.)
Distribution
from FNA
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]
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AL; AR; AZ; CA; CO; 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; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; SPM; Greenland; Eurasia [Introduced in North America; introduced also in s South America, s Africa, Pacific Islands (Hawaii, New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
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 pratense is morphologically variable and numerous varieties have been recognized (M. Zohary and D. Heller 1984). Distinctions among these are slight and intergradation is common, perhaps due to the long-time cultivation of the species. In North America, the following varieties are sometimes recognized: var. pratense with stems decumbent to ascending, 20–40 cm, with dense, appressed, white hairs; var. sativum Schreber with stems mostly erect, 40–100 cm, sparsely hairy or glabrous; and var. americanum Harz with stems 30–100 cm, with dense, spreading hairs.

(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
T. albopurpureum, T. alexandrinum, T. amoenum, T. amphianthum, T. andersonii, T. andinum, T. angustifolium, T. appendiculatum, T. arvense, T. attenuatum, T. aureum, T. barbigerum, T. barnebyi, T. beckwithii, T. bejariense, T. bifidum, T. bolanderi, T. brandegeei, T. breweri, T. buckwestiorum, T. calcaricum, T. campestre, T. carolinianum, T. cernuum, T. ciliolatum, T. columbinum, T. cyathiferum, T. dasyphyllum, T. dedeckerae, T. depauperatum, T. dichotomum, T. douglasii, T. echinatum, T. eriocephalum, T. fragiferum, T. friscanum, T. fucatum, T. glomeratum, T. gracilentum, T. grayi, T. gymnocarpon, T. haydenii, T. hirtum, T. howellii, T. hybridum, T. hydrophilum, T. incarnatum, T. jokerstii, T. kentuckiense, T. kingii, T. lappaceum, T. latifolium, T. leibergii, T. lemmonii, T. longipes, T. lupinaster, T. macilentum, T. macraei, T. macrocephalum, T. medium, T. microcephalum, T. microdon, T. monanthum, T. mucronatum, T. nanum, T. nigrescens, T. obtusiflorum, T. oliganthum, T. ornithopodioides, T. owyheense, T. palmeri, T. parryi, T. pinetorum, T. piorkowskii, T. plumosum, T. polyodon, T. pratense, T. productum, T. reflexum, T. repens, T. resupinatum, T. retusum, T. rollinsii, T. siskiyouense, T. sonorense, T. stoloniferum, T. striatum, T. subterraneum, T. suffocatum, T. thompsonii, T. tomentosum, T. trichocalyx, T. variegatum, T. vesiculosum, T. virginicum, T. willdenovii, T. wormskioldii
T. albopurpureum, T. alexandrinum, T. amoenum, T. amphianthum, T. andersonii, T. andinum, T. angustifolium, T. appendiculatum, T. arvense, T. attenuatum, T. aureum, T. barbigerum, T. barnebyi, T. beckwithii, T. bejariense, T. bifidum, T. bolanderi, T. brandegeei, T. breweri, T. buckwestiorum, T. calcaricum, T. campestre, T. carolinianum, T. cernuum, T. ciliolatum, T. columbinum, T. cyathiferum, T. dasyphyllum, T. dedeckerae, T. depauperatum, T. dichotomum, T. douglasii, T. dubium, T. echinatum, T. eriocephalum, T. fragiferum, T. friscanum, T. fucatum, T. glomeratum, T. gracilentum, T. grayi, T. gymnocarpon, T. haydenii, T. hirtum, T. howellii, T. hybridum, T. hydrophilum, T. incarnatum, T. jokerstii, T. kentuckiense, T. kingii, T. lappaceum, T. latifolium, T. leibergii, T. lemmonii, T. longipes, T. lupinaster, T. macilentum, T. macraei, T. macrocephalum, T. medium, T. microcephalum, T. microdon, T. monanthum, T. mucronatum, T. nanum, T. nigrescens, T. obtusiflorum, T. oliganthum, T. ornithopodioides, T. owyheense, T. palmeri, T. parryi, T. pinetorum, T. piorkowskii, T. plumosum, T. polyodon, T. productum, T. reflexum, T. repens, T. resupinatum, T. retusum, T. rollinsii, T. siskiyouense, T. sonorense, T. stoloniferum, T. striatum, T. subterraneum, T. suffocatum, T. thompsonii, T. tomentosum, T. trichocalyx, T. variegatum, T. vesiculosum, T. virginicum, T. willdenovii, T. wormskioldii
Synonyms Chrysaspis dubia, T. minus T. pensylvanicum
Name authority Sibthorp: Fl. Oxon., 231. (1794) Linnaeus: Sp. Pl. 2: 768. (1753)
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