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big-head clover, large-head clover

Hayden's clover

Habit Herbs perennial, 5–25 cm, villous. Herbs perennial, 5–10 cm, glabrous.
Stems

erect or ascending, branched.

ascending, cespitose, short-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.

mostly basal, palmate;

stipules lanceolate, 0.4–0.8 cm, margins entire or lobed, apex acute or acuminate;

petiole 1–6 cm;

petiolules to 0.5 mm;

leaflets 3, blades broadly ovate, 0.4–2 × 0.3–1.5 cm, base cuneate, veins thickened distally, ± straight, sometimes arching distally, 0.5+ mm apart, 5–10 pairs of primary veins, margins sharply antrorse-serrate, apex acute, short-apiculate, surfaces glabrous.

Inflorescences

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

involucres absent.

terminal, 5–20-flowered, erect, globose or subglobose, 0.5–1.5 × 0.8–2.5 cm, rachis prolonged beyond flowers, undivided or forked, often bearing sterile flower buds distally;

involucres a narrow, membranous, dentate rim, 0.5 mm.

Peduncles

2–8 cm.

straight distally, proximal to inflorescence, 5–8 cm.

Pedicels

erect, 1–1.5 mm;

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

strongly reflexed, 1.5 mm;

bracteoles broadly ovate, truncate, membranous, to 0.5 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.

13–17 mm;

calyx campanulate, 4.5–6.5 mm, glabrous, veins 10 (5 sometimes faint), tube 2–3 mm, lobes subequal, narrowly triangular-subulate, equaling tube, orifice open;

corolla salmon, buff-pink, or pink, with white or cream tips, 13–17 mm, banner broadly elliptic-oblong, 13–17 × 6–8 mm, apex rounded, retuse or slightly apiculate.

Legumes

ovoid, 4–5 mm.

stipitate, obovoid-oblong, 6–7 mm.

Seeds

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

1–4, brown, lenticular-ovoid, 2.5–3 mm, smooth.

2n

= 32, 48.

= 16.

Trifolium macrocephalum

Trifolium haydenii

Phenology Flowering Apr–Jun. Flowering Jun–Aug.
Habitat Rocky places, hard, compacted clay-gumbo, lava beds, sage-covered slopes, full sun. Alpine and subalpine slopes.
Elevation 80–2500 m. (300–8200 ft.) 2200–3800 m. (7200–12500 ft.)
Distribution
from FNA
CA; ID; NV; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
ID; MT; WY
[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 haydenii, which is found in east-central Idaho, southwestern Montana, and northwestern Wyoming, appears related to T. kingii, T. productum, and similar species (J. M. Gillett 1972) and is sometimes confused with T. latifolium (Gillett 1969), from which it differs by the absence of 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. 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. 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 T. idahoense
Name authority (Pursh) Poiret in J. Lamarck et al.: Encycl., suppl. 5: 336. (1817) Porter in F. V. Hayden: Prelim. Rep. U.S. Geol. Surv. Montana, 480. (1872) — (as haydeni)
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