Lupinus

The iconic Texas state flower — a low, mounding winter-and-spring annual legume that carpets roadsides, fields, and hillsides across central Texas with sheets of blue. From a fall sowing it overwinters as a low rosette, then in spring sends up dense, cone-shaped spikes of fragrant pea-like flowers, deep blue with a white (aging to reddish-purple) eye on the upper petal. Native to Texas and a few adjacent areas, it is the species behind the famous spring bluebonnet displays. As a legume it fixes its own nitrogen and reseeds freely, thriving on poor, dry, gravelly, often alkaline soil in full sun — the lean conditions that defeat fussier flowers. One load-bearing caution: like other lupines, Texas bluebonnet is TOXIC. Its seeds and foliage carry quinolizidine alkaloids that are poisonous to livestock and people, so it is a flower to admire, not to eat. Plant it for the spring spectacle and the bees, keep it where children and grazing animals will not browse it, and let it self-sow for next year.

The native sundial lupine of eastern North American sand barrens and oak savannas — erect 1-2.5-foot stems carry showy spring spikes of blue, pea-shaped flowers above palmately divided leaves of 7-11 radiating leaflets. A nitrogen-fixing legume of dry, sandy, acidic soils, it is the sole larval host for the federally endangered Karner Blue butterfly and the Frosted Elfin, and carries the Xerces Society "special value to native bees and bumble bees" flag.