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big-head clover, large-head clover

coast clover, cow clover, cows clover, salt marsh clover, springbank clover, wormskjold's clover

Habit Herbs perennial, 5–25 cm, villous. Herbs perennial, 10–40 cm, glabrous; rhizomes elongate.
Stems

erect or ascending, branched.

erect, ascending, or decumbent, 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 ovate to lanceolate, 1.5–2 cm, margins entire (proximal stipules) or lacerate (distal stipules), apex acute to acuminate;

petiole 1–11 cm;

petiolules 0.5 mm;

leaflets 3, blades obovate to elliptic, 0.4–4.2 × 0.2–1.3 cm, base cuneate or rounded, veins fine or thickened distally, margins spinulose-serrate, apex usually acute to rounded, sometimes retuse or mucronate, surfaces glabrous.

Inflorescences

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

involucres absent.

axillary or terminal, 20–50-flowered, subglobose or globose, 1.8–2.5 × 2–2.5 cm;

involucres broadly bowl-shaped, 12–20 mm, incised 1/3–1/2 their length, lobes 10+, sharply and acutely serrate, veins prominent.

Peduncles

2–8 cm.

1.5–11 cm.

Pedicels

erect, 1–1.5 mm;

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

straight, 1.5–2 mm;

bracteoles linear or ovate, 1–2 mm.

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.

12–14 mm, odor somewhat unpleasant;

calyx whitish, tubular, 5–6 mm, glabrous, veins 10, tube 2–3 mm, lobes green to purple, subequal, abaxial rarely longer than tube, orifice open;

corolla usually magenta to purple, rarely white or bicolored, 10–12 mm, banner ovate-oblong, 12–14 × 2–3 mm, apex truncate or rounded, slightly retuse.

Legumes

ovoid, 4–5 mm.

oblong, 2–4 mm.

Seeds

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

3 or 4, brown, sometimes mottled, subglobose or mitten-shaped, 1.5 mm, smooth.

2n

= 32, 48.

= 16, 32.

Trifolium macrocephalum

Trifolium wormskioldii

Phenology Flowering Apr–Jun. Flowering Mar–Sep.
Habitat Rocky places, hard, compacted clay-gumbo, lava beds, sage-covered slopes, full sun. Saline flats, beaches, meadows, grassy areas, alluvial soils.
Elevation 80–2500 m. (300–8200 ft.) 0–2700 m. (0–8900 ft.)
Distribution
from FNA
CA; ID; NV; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; CO; ID; NM; NV; OR; UT; WA; WY; BC; Mexico (Baja California)
[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 wormskioldii is largely tetraploid and is widespread in western North America. Distinguishing T. wormskioldii from closely allied species (especially T. mucronatum) is sometimes difficult, which led R. C. Barneby (1989) to synonymize T. mucronatum and T. pinetorum under the former name. Trifolium wormskioldii produces long, white rhizomes; T. mucronatum produces only short rhizomes at most, often only small, fibrous roots or taproots (J. M. Gillett 1980). The distinction of T. pinetorum from T. wormskioldii was supported by N. W. Ellison et al. (2006); those authors did not include material of T. mucronatum in their DNA analyses.

Trifolium wormskioldii rhizomes may have been a food resource for Native American groups in the Pacific Northwest (N. J. Turner and H. V. Kuhnlein 1982).

(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. 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. 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
Synonyms Lupinaster macrocephalum Lupinaster wormskioldii, T. fendleri, T. fimbriatum, T. heterodon, T. spinulosum
Name authority (Pursh) Poiret in J. Lamarck et al.: Encycl., suppl. 5: 336. (1817) Lehmann: Index Seminum (Hamburg) 1825: 17. (1825)
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