Definition that contains biennia
- beet biennial Eurasian plant usually having a swollen edible root; widely cultivated as a food crop
- hound's-tongue biennial shrub of Europe and western Asia having coarse tongue-shaped leaves and dark reddish-purple flowers
- barbarea biennial or perennial herbs of north temperate regions: winter cress
- woolly thistle biennial Eurasian white hairy thistle having pale purple flowers; naturalized in North America
- melilotus officinalis biennial yellow-flowered Eurasian plant having aromatic leaves used as carminative or flavoring agent; widely cultivated especially as green manure or cover crop
- erysimum arkansanum biennial or short-lived perennial prairie rocket having orange-yellow flowers; western North America to Minnesota and Kansas; sometimes placed in genus Cheiranthus
- melilotus alba biennial plant; valuable honey plant
- mentzelia livicaulis biennial of southwestern United States having white stems and toothed leaves that is grown for its large pale yellow flowers that open in early morning
- onopordon acanthium biennial Eurasian white hairy thistle having pale purple flowers; naturalized in North America
- cynoglossum officinale biennial shrub of Europe and western Asia having coarse tongue-shaped leaves and dark reddish-purple flowers