Trifolium amoenum
Trifolium wormskioldii
showy Indian clover, two-fork clover
coast clover, cow clover, cows clover, salt marsh clover, springbank clover, wormskjold's clover
erect, branched from base and distally, or unbranched.
erect, ascending, or decumbent, branched.
palmate;
stipules ovate-oblong, 0.5–1.8 cm, margins entire, toothed, or irregularly lobed, apex acuminate;
petiole 0.5–10 cm;
petiolules to 1 mm;
leaflets 3, blades broadly obovate or elliptic, 1.7–3.3 × 1.1–2 cm, base cuneate, veins fine, margins entire or denticulate, apex rounded, obtuse, or retuse, surfaces pilose, abaxial less so.
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.
terminal or axillary, 30–50-flowered, bluntly conic, ellipsoid, globose, or subglobose, 1.5–3 × 1.5–2.5 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.
5–15 cm.
1.5–11 cm.
absent;
bracteoles cuplike, to 0.5 mm.
straight, 1.5–2 mm;
bracteoles linear or ovate, 1–2 mm.
13–16 mm;
calyx tubular, 9–12 mm, pubescent, veins 20–30, tube 3 mm, lobes nearly equal, appearing rigidly erect, linear-setaceous, plumose, sinuses acute, orifice open;
corolla white to pink with purple tips, 12–16 mm, banner ovate-oblong, 12–15 × 4 mm, apex broadly rounded, 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.
obovoid, 4 mm.
oblong, 2–4 mm.
1, dark brown, ellipsoid, 2–3 mm, smooth.
3 or 4, brown, sometimes mottled, subglobose or mitten-shaped, 1.5 mm, smooth.
= 16, 32.
Trifolium amoenum
Trifolium wormskioldii
Trifolium amoenum was considered extinct (J. P. Smith Jr. 1984) but was rediscovered in 1993 (P. G. Connors 1994). Specimens of T. amoenum are known from Marin, Napa, San Mateo, Solano, and Sonoma counties; it appears to be extant in only single populations in each of Marin and Solano counties. Allozyme studies of the two known populations revealed fixed genetic differences between them (E. E. Knapp and Connors 1999).
(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.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
PNW Herbaria, Turner Photog. 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
