silphium (silfium)

[L., the tribe Helianthoideæ and subtribe Melampo dieæ. It is distinguished by its large flower-heads with a broad involucre, sterile disk-flowers, and pistillate and fertile strap-shaped ray-flowers in one or two rows, producing compre ed achenes bordered by two wings which are toothed or awned at the apex. Twenty species have been described, of which eleven are now considered distinct. They are all natives of the United States, chiefly in the Mi i ippi valley and Southern States. They are tall rough hairy perennials, with a resinous juice, bearing alternate, opposite, or whorled leaves of various shapes, and either entire, toothed, or lobed. The yellow flowers (in one species the rays are white) are borne in long-stalked heads, which are solitary or loosely corymbed. S. terebinth in a ceum, remarkable for its odor of turpentine, is the prairie dock of the west. For S. per folia tum, see cup - plant; and for S. lacinia tum, see rosin - weed and compa - plant. silphologic (sil-fo-loj'ik), a. [