Natural Notes: Native Sunflowers

September is the month of yellow, and for gardeners the easy-to-grow and popular choice of flower  is the Annual Sunflower (Helianthus annuus) which adorns garden borders and roadsides across the Chicago Region.  Numerous cultivars of this urban weed have been developed, and the source of commercial sunflowers and sunflower oil are derived from the Annual Sunflower (figure 1). 
Figure 1:  Annual Sunflower growing
 at the Taylor Street Farms
community garden in Chicago.  

But prior to European settlement, the Chicago region was largely absent of this tall and showy late-summer wildflower, whose range historically included the south-central United States into the plains and grasslands just to the east of the Rocky Mountains.  Instead, the prairie landscape of Northern Illinois would have been adorned with several species of native sunflowers and sunflower-like plants (figure 2). 
Figure 2:  Although virtually absent of the notorious Annual Sunflower,
the prairie landscape of Northern Illinois
was filled with plenty of yellow blossoms.  

True sunflowers are in the genus Helianthus and over 90% of species in this genus are native to North America.  There are also many other species of sunflower-like plants who are primarily members of the Aster family.   Let's meet some of the other sunflower species of the Prairie State as well as a few of their Aster cousins.

True Sunflowers
Sawtooth Sunflower (H. grosseserratus) is common in September in suburban forest preserves as well as any remnant or restored tallgrass prairies (see figure 3 and video clip).  Climbing over 12 feet into the air, this showy native sunflower attracts countless pollinators, and its roots extend several feet into the soil, allowing them to survive wildfires and mowing.  Their deep roots stabilize the soil beneath, as well.  Once established, Sawtooth Sunflowers can form dense clusters that can quickly fill a pollinator garden or wildflower area. 

Figure 3:  Sawtooth Sunflowers in bloom in the Chicago suburbs













Hairy Sunflower (H. hirsutus) is similar to Sawtooth Sunflower and grows in similar habitats, but its flower petals are more separated and it has a darker center area.  The leaves are somewhat rough and "hairy".  Figure 4 shows one growing in a sunny woodland edge at a suburban forest preserve not far from the Taylor Street Farms in Chicago. 




Figure 4:  Hairy Sunflower blooming brightly.  

Who says sunflowers only grow in full sun?  Woodland Sunflower (H. divaricatus) is another native sunflower, and unlike most, this one grows in semi-shady woodland areas.  The flowers are a little bit smaller, but just as bright, and the leaves clasp the stem.  Also, this wildflower typically blooms earlier in the year, usually late June and July, although it can also still bloom later in the season (figures 5 & 6).  Woodland sunflowers are common in open woodland areas found in larger parks, gardens as well as forest preserves in the Chicago area, but are uncommon nowadays elsewhere. 
Figure 5:  Clasping leaves of Woodland Sunflower.  Photo credits:  Illinoiswildflowers.org

Figure 6:  Blossoms of Woodland Sunflower.  Photo credits:  Illinoiswildflowers.org

Similar Wildflowers
There are also many species of bright yellow flowers that resemble sunflowers but belong to other groups of plants.

Cup Plant (Silphium perfoliatum, Figure 7) is a common prairie wildflower likely named for the cup-like area where the leaves clasp the stem (figure 8).  This area holds a small amount of water, which serves as a valuable source of water for insects, birds, and other wildlife who live in dry and hot prairies.  Cup plant can grow in excess of 12 feet and thrives in open, sunny areas and is drought-tolerant. 
Figure 7:  Cup Plant in bloom.  

Figure 8:  Water-filled depression where the leaves clasp the stem
 is a signature feature of Cup Plant


False Sunflower (Heliopsis helianthoides).  Due to subtle differences in its flowering structure, this wildflower of woodland edges is quite common in gardens as well, and its bright yellow flowers that bloom in late July and August resemble those of our native sunflowers (figure 9)


Figure 9:  False Sunflower.  Photo credits:  Illinoiswildflowers.org


Tall Coreopsis (Coreopsis tripteris) has small but numerous showy yellow flowers with a black center.  This late-summer bloomer thrives in dry and sunny areas, and is often planted in prairie restoration sites.  It has thinly lobed leaves and can grow close to 10 feet, though it is usually shorter.  See figures 10 & 11 to admire this native prairie wildflower. 









Figure 10:  Tall Coreopsis growing in a prairie outside of Chicago

Figure 11:  Blossoms of Tall Coreopsis
Native sunflowers and their allies attract countless pollinators and have deep roots that can protect topsoil.  Planting them can help diversity our yards, gardens and communities.  Native sunflowers are slower growing than Annual Sunflowers, and are slightly less tolerant of disturbance, however they are still easy to grow and they're an important component of our lost prairie ecosystems.  They are also quite stunning!  Perhaps next year you'll consider planting a few, such as the lovely Compass Plant shown in Figure 12? 

For more information about other species of native sunflowers and similar, click here.  And be sure to get out and see native sunflowers in their natural habitat by visiting a local park district natural area or a suburban forest preserve

Figure 12:  Compass Plant (S. laciniatum).  Photo credits:  Illinoiswildflowers.org

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