Delphinium, the name of an extensive genus of annual or perennial herbaceous plants belonging to the natural order of ranuncidaceae. They have handsome irregular flowers, resembling somewhat the fanciful figures of the dolphin or the spurs of larks, and are commonly known as larkspurs. The genus is nearly allied to the aconites. The seeds, especially of D. staphisagria (stavesacre) and D. consolida (branching larkspur), are powerfully cathartic, and owing to the violence of their operation are seldom given internally; they are, however, employed in destroying vermin. The extract (delphinia) has been used in tic douloureux, paralysis, and rheumatism. The blossoms of the delphiniums are very showy, and in some sorts they are even extremely rich and magnificent. Those known as the rocket larkspurs have elegantly colored flowers, though they are apt to exhibit too light and less showy tints. The double kinds of these are very attractive in early summer. Their seeds are sown in finely pulverized and rich soil in autumn, either in beds, in patches, or in single rows, as fancy or taste may dictate. If allowed to stand too close together, the flower spikes are not so well developed. Sometimes they are used to succeed the blooming of hyacinths, and are accordingly sown in or near hyacinth beds.
The interstices of tulip beds are sometimes sown with them in the same way; and thus the period of the fading of the flowers of the bulbs is enlivened by the spikes of the larkspurs bearing their hyacinth-like blooms. The few weeks previous to the proper time for taking up the bulbs exhaust the beauty of the larkspurs, so that they can be removed together. The perennial delphiniums are conspicuous for size and altitude. They vary, however, in both these particulars. Some grow from 5 to 6 ft. high in a few weeks, having spikes of coarse blue or pale blue flowers. Others are more supine, have weaker flower stems, and a more divided and more graceful and delicate foliage. The blossoms of such are proportion ably more beautiful, varying from the intensest blue or azure to a paler color, and so shading off by degrees to a pearly or opalescent tint. Cultivation has produced many extraordinary and double sorts, of which the D. grandiflorum, or Chinese, as it is sometimes called, and Buck's seedling are among the finest. These perennials are, however, herbaceous, all dying down to the root and rising again with strong shoots in the next year.
From a singular resemblance of the inner petals, especially in the single flowers, to the body of a bee, they have been called bee larkspurs, the pubescence accompanying them helping the illusion by its seeming to be hairs. The species native in the United States are D. exaltatum (Mx.), with a stem from 2 to 5 ft. high and purplish blue flowers, occurring in Pennsylvania; D. tricorne (Mx.), a pretty species of a foot high, seen in Ohio; and D. azureum (Mx.), a characteristic species in Iowa and Minnesota. One other has been naturalized, D. consolida (Linn.), having escaped from grain fields and appearing on the sides of the roads, like many other foreign species introduced by seeds from abroad, either for the garden or in field husbandry. A splendid scarlet-flowered delphinium was discovered by Dr. Parry in 1850, on the mountains east of San Diego; it is D. coccineum(Torrey, in "Mexican Boundary Survey"). Another scarlet-flowered species is known as D. nudicante.