cup clover as seen in a moist ditch along Forest Service Road 16 at Summit Prairie, Malheur National Forest..................August 20, 2011.
Cup clover is an annual clover with ascending to erect stems from 10-50 cm high. The leaves are ternately compound (3 leaflets) with long petioles. The individual leaflets are oblanceolate to obcordate in shape (See photos.) and range from 5-25 mm long.
The flower heads are rounded with 5 to 30 flowers. The flower heads range form 5-15 mm wide. Individual flowers are white to yellowish-white, with the corolla barely extending past the calyx. The involucre below the flower head is widely flared to cup-shaped (hence the common name) with 6-14 shallow lobes, the margins finely toothed. The seed pod is 2-seeded.
Cup clover may be found in dry sandy soils to wet meadows within its range.
Cup clover may be found from British Columbia south along the eastern side of the Cascade Mts. to California and eastward to Idaho. It has also been introduced along the Pacific coast from Juneau, Alaska to Los Angeles, CA.