Wholeleaf Rosinweed (Silphium integrifolium)
Aster Family (Asteraceae)
Wholeleaf rosinweed is an erect, clump-forming, perennial herb, reaching 3 feet tall, but sometimes to 6 feet tall. Its stout stems are usually hirsute (with stiff hairs) (glabrous with age) and arise from a taproot and short rhizomes. It has a resinous gummy sap which is exuded when the plant is cut or broken. The sparse, stalkless, opposite (sometimes alternate or whorled) leaves are ovate to elliptic to lance-shaped and coarse due to stiff hairs. They may be toothed or not and hairless to woolly. The flower heads have yellow ray flowers and yellow disc flowers. Only the ray florets are fertile. Each flower head is subtended by bracts with reflexed tips. Flowers from July to September. Bees frequently visit the flowers, while some butterflies and flies also visit them sometimes. Found throughout much of the central United States. It occurs in rocky or dry open woods, glades, and prairies in full sun on well-drained soils. Birds eat the large flat seeds. The resin has been chewed like gum. The roots have been used as an analgesic. Has 5 subspecies. Also known as rosinweed and entire-leaf rosinweed.
Listed as Threatened by MI.
Copyright Brett Miley
