Helianthus Genus sunflower Asteraceae

  

Helianthus petiolaris.Max Licher.Southwest Envirnonmental Information Network.swbiodiversity.org.seinet

Helianthus petiolaris.Max Licher.Southwest Envirnonmental Information Network.swbiodiversity.org.seinet (Access 4/2014).

Helianthus is a genus of herbs, coarse annuals or perennials, stems erect, branching mostly opposite, becoming somewhat woody in age. 

Leaves opposite or upper ones alternate, blade simple. 

Flowers mostly yellow, rays without male or female parts (neutral), large, disk fflowers fertile, perfect (both male and female), basal bracts usually green, ffloral base (receptacle ) covered with dry, thin scales; most common pollinators probably bees and butterflies, Lepidoptera (Robertson 1922). 

Fruit dry, 1-seeded achene, crowned by two deciduous scales. 

Notes: Winter plants usually with scaly receptacle and some upper leaves persistent (Levine 1995). Helianthus petiolaris.www.opsu.edu