Silphium is a genus of North American plants in the tribe Heliantheae within the family Asteraceae.
Members of the genus, commonly known as rosinweeds, are herbaceous perennial plants growing to to more than tall, with yellow (rarely white) flowerheads that resemble sunflowers. In the rosinweeds, the outer florets in the head are fertile and the inner florets are sterile; in the sunflowers, the reverse is true.
The name of the genus comes from the Ancient Greek word for a North African plant whose identity has been lost, though it is known its gum or juice was prized by the ancients as a medicine and a condiment.
Species
Species in the genus include: Silphium albiflorum A.Gray – white rosinweed – TX Silphium asteriscus L. – starry rosinweed – TX OK LA AR MO IL IN KY TN AL MS GA FL SC NC VA WV OH MD PA NY Silphium brachiatum Gatt. – Cumberland rosinweed – TN AL GA Silphium compositum Michx. – kidneyleaf rosinweed – TN AL GA FL SC NC VA WV Silphium glutinosum J.R. Allison AL Silphium integrifolium Michx. – wholeleaf rosinweed – NM TX LA OK AR MO KS CO WY SD NE IA IL IN KY TN MS AL WI MI MA ONT Silphium laciniatum L. – compassplant – NM TX LA OK AR MO KS CO SD NE MN IA IL IN KY TN MS AL WI MI VA PA NY ONT Silphium laeve Hook. Silphium mohrii Small – Mohr's rosinweed – TN AL GA Silphium perfoliatum L. – cup plant – NM TX LA OK AR MO KS CO SD ND NE MN IA IL INKY TN MS AL WI MI NC VA DE PA NY NJ CT RI MA VT NH ME ONT QUE NB Silphium perplexum J.R.Allison – Old Cahaba rosinweed – AL Silphium pinnatifidum Elliott – Cutleaf prairie dock – AL GA KY TN Silphium radula Nutt. – roughstem rosinweed – KS MO AR OK TX LA Silphium terebinthinaceum Jacq. – prairie rosinweed, prairie dock – IA MO AR MS AL GA SC NC VA WV TN KY OH IN IL WI MI NY ONT Silphium ternatum Sessé & Moc. – Mexico Silphium trifoliatum L. – whorled rosinweed – AL GA IN KY MD NC SC OH PA VA WV Silphium wasiotense M.Medley – Appalachian rosinweed – KY TN
Formerly included
Numerous species are now regarded as members of the genera Berlandiera and Verbesina.