Silphium asteriscus Rosinweed is a 3-foot tall, herbaceous perennial. The leaves are alternate, sometimes opposite, and are covered by fine hairs. Lemon-yellow flower heads about the size of silver dollars appear in late summer. The name rosinweed comes from the resinous sap, which, when dried, was used by Native Americans as breath-freshening chewing gum. Note that there is a high level of local variability throughout its range.