woodland sunflower (EwA Guide to the Plants of the Fells (US))

woodland sunflower

Helianthus divaricatus

Summary ⁶

Helianthus divaricatus, commonly known as the rough sunflower, woodland sunflower or rough woodland sunflower, is a North American species perennial herb in the composite family. It is native to central and eastern North America, from Ontario and Quebec in the north, south to Florida and Louisiana and west to Oklahoma and Iowa.

Comments ⁷

The Woodland Sunflower is easily identified by its sessile, or nearly sessile, opposite leaves. Other sunflowers (Helianthus spp.) have longer petioles. Its stems are usually hairless or mostly hairless, unlike Helianthus hirsutus (Hairy Sunflower) and some other species in this genus. Compared to some narrow-leaved sunflowers that occur in prairies, the leaf bases of Woodland Sunflower are more broad and nearly truncate. Some parasitic plants that occasionally attach their haustoria (root-like extensions) to sunflowers and other species in the Aster family include Cuscuta glomerata (Rope Dodder) and other Cuscuta spp. (generally in moist areas that are often sandy), and Orobanche ludoviciana (Prairie Broomrape) and other Orobanche spp. (generally in dry areas that are often sandy). These parasitic plants can significantly weaken the host plants to which they become attached.