There are about 340 species of delphinium if you include, as some authors do, 40 Old World species in the genus Consolida. Of the 300 species in the genus Delphinium, all contain high levels of the alkaloid delphinine, and are toxic to livestock. All have deeply palmately lobed leaves, petals smaller than the sepals, and a spurred upper sepal. Prairie larkspur (Delphinium carolinianum) blooms from May to June on dry prairies and open woodlands. It is distinguished by the moderately to densely hairy stem; erect flower stalks that appear appressed to the inflorescence axis; four petals; three to five pistils; and densely ridged seedcoat.
There are four subspecies of prairie larkspur. Only one, Delphinium carolinianum ssp. virescens, is found in Minnesota. This subspecies is identified by its height usually more than 18″; a branched horizontal root system; basal leaves still present at flowering time; leaf blade with 5 to 7 primary segments; uppermost leaf stalk more than 3 ⁄16″ long; and white to very pale blue sepals.