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woolly-head clover

bull clover, sour clover

Habit Herbs perennial, 12–46 cm, sparsely hairy to densely villous, appressed-pubescent, or glabrate. Herbs annual, 10–80 cm, glabrous or glabrescent.
Stems

erect or decumbent, branched.

erect or ascending, unbranched or densely dichotomously branched.

Leaves

palmate;

stipules lanceolate or ovate, 1–5 cm, margins entire or denticulate, apex acuminate or acute;

petiole 1–15 cm;

petiolules 1 mm;

leaflets 3, blades linear, linear-elliptic, elliptic, lanceolate, lanceolate-oblong, or obovate, 1–5 × 0.4–1.2 cm, base cuneate, veins fine or ± thickened, margins denticulate or serrulate, apex acuminate or acute, surfaces appressed-pubescent abaxially, glabrous, densely villous, or sparsely or densely pilose adaxially.

palmate;

stipules ovate or lanceolate, 1–3 cm, margins entire or toothed, apex usually acuminate, sometimes 2-fid;

petiole 3–15 cm;

petiolules 1–1.5 mm;

leaflets 3, blades broadly obovate, orbiculate, or rhombic-obovate, 0.8–4 × 0.7–3 cm, base broadly cuneate, veins obscure, thickened near leaflet margin, margins remotely dentate to densely serrulate-dentate, apex rounded or slightly retuse, surfaces glabrous or glabrate.

Inflorescences

terminal or axillary, 25–70-flowered, inverted or horizontal, ellipsoid or globose to subglobose, 2–3 × 1–3 cm, rachis prolonged beyond flowers;

involucres absent.

terminal or axillary, 10–30-flowered, subglobose or globose, 1–4 × 1–4 cm;

involucres broadly bowl-shaped, 4–15 mm, lobes 3–8, lanceolate, acuminate, undivided or 2- or 3-fid.

Peduncles

bent distally, proximal to flowers, 3–18 cm.

3–13 cm.

Pedicels

reflexed, to 0.3 mm;

bracteoles absent.

straight, 1 mm;

bracteoles distinct or connate, broadly ovate, 1 mm.

Flowers

9–18 mm;

calyx campanulate, curved in fruit, 4–11 mm, villous, veins 10, tube 1.5–2.5 mm, lobes unequal, 2–3 times tube, subulate, often strongly curved and twisted, plumose, orifice open;

corolla white, cream, or purple, 8–16 mm, banner oblanceolate, 8–16 × 3–5 mm, apex rounded or retuse, recurved;

ovaries pubescent distally.

10–27 mm;

calyx campanulate, 3–8 mm, glabrous, veins 10, tube 1.5–2.5 mm, lobes 5–10, unequal, undivided or 3-fid, long-acuminate, orifice open;

corolla creamy white to yellow, pink to purple in age, keel petals rarely dark purple, 10–27 mm, banner broadly ovate, inflated in fruit, not distally twisted, 10–27 × 6–15 mm, apex rounded, erose.

Legumes

ovoid, 2–3.5 mm.

stipitate, linear, 7–8 mm.

Seeds

(1 or)2–4, yellow-brown to brown, mitten-shaped or subglobose, 1.2–2 mm, smooth.

3–8, gray, mottled, globose, 1.6–2 mm, reticulate.

2n

= 16.

Trifolium eriocephalum

Trifolium fucatum

Phenology Flowering Apr–Jun.
Habitat Moist places, meadows, road­sides.
Elevation 0–1000 m. [0–3300 ft.]
Distribution
from USDA
w United States
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; OR; WA [Introduced in Asia (China, Japan)]
[WildflowerSearch map]
[BONAP county map]
Discussion

Subspecies 6 (6 in the flora).

Trifolium eriocephalum was revised by J. M. Gillett (1971). The subspecies exhibit unusually complex distributional patterns, and overlapping morphological features sometimes make identifications problematic (M. Zohary and D. Heller 1984).

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

Trifolium fucatum is known as an invasive species in Japan (T. Mito and T. Uesugi 2004) and has also been introduced in China (specimen at BM). A single old collection exists from British Columbia, but the species has not been collected in that province again. The Michigan record of the species is an inadvertent waif.

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

Key
1. Ovules usually 2, rarely 1 or 3; calyx lobes usually green, rarely purple, straight, subequal, 3–4 timestube.
→ 2
2. Herbs densely villous; leaflet blades of basal and median leaves elliptic or lanceolate-oblong; roots cylindric, thickened.
subsp. eriocephalum
2. Herbs slightly villous, appressed-pubescent, or glabrate; leaflet blades of basal and med­ian leaves usually narrowly lanceolate or lin­ear, rarely narrowly elliptic; roots fusiform-tuberous.
subsp. cascadense
1. Ovules 3 or 4; calyx lobes usually purple, contorted, abaxial lobes longer, lateral lobes 1–1.5 times tube.
→ 3
3. Leaflet blades of basal leaves linear or linear-elliptic, apex acute, surfaces sparsely or densely hairy adaxially; roots cylindric, thickened, branched, often rhizomelike.
→ 4
4. Blades of leaflets of median leaves linear or linear-elliptic; herbs slightly villous.
subsp. cusickii
4. Blades of leaflets of median leaves broadly elliptic; herbs densely villous.
subsp. villiferum
3. Leaflet blades of basal leaves obovate, apex rounded to retuse, surfaces usually glabrous adaxially, sometimes sparsely hairy; roots fusiform-tuberous.
→ 5
5. Inflorescences 2.5 cm diam., significantly overtopping distal leaves; leaflet blades of median leaves broadly lanceolate, surfaces sparsely hairy or glabrous adaxially.
subsp. arcuatum
5. Inflorescences 1 cm diam., scarcely over­topping distal leaves; leaflet blades of median leaves narrowly lanceolate or linear, surfaces densely villous adaxially.
subsp. martinii
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. 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. 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
Subordinate taxa
T. eriocephalum subsp. arcuatum, T. eriocephalum subsp. cascadense, T. eriocephalum subsp. cusickii, T. eriocephalum subsp. eriocephalum, T. eriocephalum subsp. martinii, T. eriocephalum subsp. villiferum
Synonyms T. flavulum, T. fucatum var. flavulum, T. fucatum var. gambelii, T. fucatum var. virescens, T. gambelii, T. physopetalum, T. virescens
Name authority Nuttall in J. Torrey and A. Gray: Fl. N. Amer. 1: 313. (1838) Lindley: Edwards’s Bot. Reg. 22: plate 1883. (1836)
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