Monday, August 14, 2023

Missouri Ironweed - Vernonia missurica

Florida is home to six distinct species of ironweeds (Vernonia spp.)  - all of them relatively robust with rich purple flowers.  All of this makes distinguishing them from each other a bit problematic.  What's most useful is a close look at the foliage, the overall growth form, and the habitat it occurs in.  

Missouri ironweed (V. missurica), despite its common name, is a Florida native though restricted to five counties in the far western Panhandle and in two others in the central portion of that region.  It also is reported in the central swath of states in the U.S. - from directly north of Florida (Georgia and Alabama), east to Texas and then north to Illinois, Indiana, Iowa and Michigan.  Throughout this region, it is most often found in sunny open habitats with extra moisture; though it is not considered to require wetland soils. 

Vernonia missurica is best distinguished from other ironweeds by the usually greater number of disk florets per flower head and by the hairy stems and leaf undersides. This is an upright perennial that typically grows 3-5 feet tall on stiff, leafy stems which branch at the top. Narrow, lance-shaped to narrow-ovate leaves (to 7 inches long) have serrate margins.The leaves alternate along the stems.

Flowering occurs in summer to early fall.  The individual blooms lack ray petals (which is true for all ironweeds) and occur near the tops of the main stem and in corymbose cymes arising from the upper leaf axils.  Each "head" is composed of fluffy deep purple disc flowers.  These are exceedingly attractive to butterflies and bees - a trait of all ironweeds.

I've been growing this wonderful species here at Hawthorn Hill in south Pasco County for several years and find that it's an easy species to maintain.  The seed germinates readily without cold stratification and it has adapted well to my created wetland conditions - growing in pretty much the same conditions as New York ironweed (V. novaboracensis).  If you wish to add this species to your landscape, you likely will have to purchase it from sources outside of Florida.  I do not know of anyone (other than myself) in Florida that has ever propagated it and my original seed source did not come from a Florida population.

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