Trifolium pratense
Trifolium polyodon
red clover
Pacific grove clover, woods or Pacific grove clover
erect, ascending, or decumbent, branched.
decumbent or ascending, branched.
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.
palmate;
stipules lanceolate to ovate, 0.4–1.8 cm, margins lacerate, apex acute to acuminate;
petiole 0.5–6 cm;
petiolules to 1 mm;
leaflets 3, blades broadly elliptic to broadly obovate, 0.4–2.5 × 0.4–1.5 cm, base cuneate, veins moderately thickened, margins dentate-serrulate, apex rounded or truncate, often retuse, surfaces glabrous.
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.
axillary, 10–25-flowered, subglobose or globose, 1–1.8 × 1–1.8 cm;
involucres flattened or bowl-shaped, 4–7 mm, incised 1/2 their length, when folded, not hiding flowers except proximally, lobes 5–12, dentate-lacerate, spinulose.
± 0 cm, subtended by stipules of distal leaves.
1–2 cm.
straight, 0–1 mm;
bracteoles absent.
straight, to 1 mm;
bracteoles absent.
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.
8–10 mm;
calyx campanulate-tubular, not slit between adaxial lobes, 5–7 mm, glabrous, veins 20, tube 1.9–2.4 mm, lobes unequal, 3-fid or laciniate, often appearing 7+-lobed, orifice open;
corolla pink or pale purple, 8–9 mm, banner elliptic, 8–9 × 2–3 mm, apex retuse.
oblong, leathery distally, transversely dehiscent, 3 mm.
ellipsoid, 3.5–4 mm.
1 or 2, yellow, yellow-brown, or purple, ovoid, 1.6–2 mm, smooth, dull.
2, dark brown, mottled, ovoid or reniform, 1.7–1.9 mm, smooth.
= 14.
Trifolium pratense
Trifolium polyodon
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.)
The taxonomic status of Trifolium polyodon, known only from Monterey County, has long been debated. W. L. Jepson (1936) considered it a variety of T. tridentatum Lindley (= T. willdenovii). The first to consider it as a variety of T. variegatum was J. S. Martin (1943), who never formally published a new combination; an invalid combination was made by M. Zohary and D. Heller (1984). D. Isely (1998) included it in his interpretation of T. variegatum as phase 5 of that species; he speculated that T. polyodon might have originated as a hybrid of T. variegatum and T. willdenovii. Molecular studies (N. W. Ellison et al. 2006) showed that T. polyodon is closely related to T. variegatum but is distinct; it also appears to be related to T. cyathiferum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
KS Wildflowers, 
LA Plants, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
MO Plants, 
PNW Herbaria, 
SW CO Wildflowers, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
