The Herbarium of the University of Michigan lists 15 species of the genus Helianthus Sunflowers. These are all members of the Asteraceae family (Asters) which is one of the largest families of wildflowers representing about 40,000 species.
Sunflowers are all composite flowers in that they all have a center called a disk which contains tiny petal-less flowers (florets) surrounded by colorful ray flowers mostly yellow. If you really want to dig into how botanists describe flowers, take a minuet to look at the Illinois Wildflower site. This will give you an appreciation of how precisely professionals describe the objects of their study.
Below are some of my favorite shots of Woodland Sunflowers. Be sure to notice the leaves are oppositely spaced as opposed to alternately spaced and the leaves are shaped like lances (lanceolate) and attached directly to the stem (sessile) or with very short stems (petioles).
Stewart Nelson, 2017 Some rights reserved ©
Stewart Nelson, 2017, Some rights reserved ©