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big-head clover, large-head clover

golden clover, golden hop clover, greater hop clover, hop clover, large hop clover, large hop trefoil, palmate hop clover, yellow clover

Habit Herbs perennial, 5–25 cm, villous. Herbs annual, 20–60 cm, glabrous or hirsute.
Stems

erect or ascending, branched.

erect, unbranched or profusely branched.

Leaves

palmate;

stipules ovate, obovate, or oblong, 1–3 cm, margins entire, irregularly lobed, or serrate, apex acute or acuminate;

petiole 1–14 cm;

petiolules 0.9–1.2 mm;

leaflets (5–)7–9, blades broadly to narrowly obovate, often folded, 1–2.7 × 0.4–1.1 cm, base cuneate, veins thickened, especially distally, margins serrulate, apex rounded or truncate, apiculate, surfaces villous abaxially, sparsely villous to glabrate adaxially.

palmate;

stipules oblanceolate, 0.9–1.5 cm, margins entire, apex acuminate or cuspidate;

petiole 0.8–1 cm;

petiolules 0–1 mm;

leaflets 3, blades obovate to elliptic-lanceolate, 1–2.8 × 0.6–0.8 cm, base cuneate, lateral veins prominent, ± parallel, ascending, margins denticulate, apex acute, truncate, or retuse, mucronate, surfaces glabrous or sparsely hairy.

Inflorescences

terminal, 20–32-flowered, globose or ovoid-ellipsoid, 2.5–8 × 3–7 cm;

involucres absent.

axillary or terminal, 20–80-flowered, usually ovoid-cylindric, sometimes globose, 1.2–2 × 1.3 cm;

involucres absent.

Peduncles

2–8 cm.

2–5 cm.

Pedicels

erect, 1–1.5 mm;

bracteoles broadly ovate, membranous, to 0.5 mm, truncate.

reflexed, 0.3–0.6 mm;

bracteoles a fringe of red setae.

Flowers

20–30 mm;

calyx campanulate, 10–22 mm, villous, veins 10–15, tube 2.5–4 mm, lobes subequal, subulate, plumose, orifice open;

corolla white, creamy white, or pinkish, keel petals deep pink, 20–28 mm, banner ovate or oblong, 20–28 × 10–13 mm, apex rounded or slightly emarginate.

7–8 mm;

calyx campanulate, 2–2.5 mm, glabrous, veins 5, tube 0.8–1 mm, lobes unequal, adaxial deltate, 0.6–0.9 mm, 1/2 length of abaxial, abaxial linear, orifice open;

corolla golden yellow becoming brown, 5–6 mm, banner persistent, obovate, boat-shaped, 4–4.5 × 2.4–2.6 mm, apex emarginate.

Legumes

ovoid, 4–5 mm.

stipitate, oblong, 3–3.5 mm, longer than calyx.

Seeds

1 or 2, yellow or reddish, mitten-shaped to ellipsoid, 2.5–3 mm, smooth.

1, pale yellow-green, ovoid, 1–1.2 mm, smooth, glossy.

2n

= 32, 48.

= 14, 16.

Trifolium macrocephalum

Trifolium aureum

Phenology Flowering Apr–Jun. Flowering Jun–Aug.
Habitat Rocky places, hard, compacted clay-gumbo, lava beds, sage-covered slopes, full sun. Roadsides, railroads, fields, disturbed woodland glades.
Elevation 80–2500 m. (300–8200 ft.) 0–1700 m. (0–5600 ft.)
Distribution
from FNA
CA; ID; NV; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CA; CT; DC; DE; GA; IA; ID; IL; IN; KY; MA; MD; ME; MI; MN; MO; MT; NC; NH; NJ; NY; OH; OR; PA; RI; SC; TN; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NL; NS; ON; PE; QC; SK; SPM; n Europe; c Europe; w Asia [Introduced in North America; introduced also in s South America (Argentina, Chile), e Asia (e China), Pacific Islands (New Zealand), Australia]
[WildflowerSearch map]
[BONAP county map]
Discussion

Trifolium macrocephalum has the largest inflorescences of any clover. Trifolium megacephalum Nuttall (1818) is an illegitimate replacement name for Lupinaster macrocephalum Pursh.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Trifolium agrarium Linnaeus is a rejected name that has been used historically for T. aureum (J. E. Dandy 1958; N. J. Turland et al. 1996).

(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. 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. 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. 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. 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
Synonyms Lupinaster macrocephalum Chrysaspis aurea
Name authority (Pursh) Poiret in J. Lamarck et al.: Encycl., suppl. 5: 336. (1817) Pollich: Hist. Pl. Palat. 2: 344. (1777)
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