The Genus Lotus
Birdsfoot Trefoil, Birdsfoot-trefoil, Garden Bird's-foot Trefoil, Birdfoot Deervetch: Lotus corniculatus (Synonyms: Lotus corniculatus var. arvensis, Lotus tenuis) - Perennial. Leaves sessile with 5 leaflets. Flowers yellow, in clusters of 3-15 in compact umbels.
Big Deervetch, Thick-leaf Deer-vetch: Lotus crassifolius var. crassifolius (Synonym: Hosackia crassifolia) - Perennial. Leaves petiolate with 9-23 leaflets. Flowers greenish-yellow, often spotted with deep purple.
Rosy Birdsfoot Trefoil, Rosy Bird's-foot Trefoil, Thicket Deer Vetch: Lotus aboriginus (Synonyms: Hosackia rosea, Lotus crassifolius var. subglaber, Lotus stipularis var. subglaber) - Perennial. Leaves petiolate with 9-23 leaflets. Flowers whitish, tinged with red or purple.
Desert Deervetch, Field Lotus, Short-flower Bird's-foot Trefoil, Small-flowered Deer-vetch: Lotus micranthus (Synonyms: Hosackia parviflora, Lotus parviflorus) - Annual. Leaves with mostly 5 leaflets. Flowers 4-5 mm long. Calyx teeth less than 1 mm long and much less than the length of the tube. Pods conspicuously constricted between seeds.
Nevada Deervetch, Nevada Bird's-foot Trefoil: Lotus nevadensis var. douglasii (Synonyms: Lotus douglasii, Lotus nevadensis var. nevadensis) - Perennial. Leaves petiolate with 5 leaflets. Flowers yellowish. Pods strongly curved or sickle-shaped.
Bog Deervetch, Meadow Bird's-foot Trefoil, Meadow Deervetch: Lotus pinnatus (Synonyms: Hosackia pinnata, Lotus bicolor) - Perennial. Leaves petiolate with 7-11 leaflets. Flowers with bright yellow banner and whitish wings (umbels look like yellow pinwheels with a white outer stripe).
American Bird's-foot Trefoil, Pursh's Lotus, Spanish-clover: Lotus unifoliatus var. unifoliatus (Synonyms: Hosackia americana, Lotus americanus, Lotus purshiana, Lotus purshianus var. glabra, Lotus purshiana var. purshiana, Lotus unifoliolatus) - Annual. Leaves with mostly 3 leaflets, although perhaps a single leaflet is present higher on the stem. Flowers 4-8 mm long. Calyx teeth mostly greatern than 2 mm long and equal to or greater than the tube. Pods slightly constricted between seeds or not so at all.