Please try our next iteration of the Michigan Flora Online here. Beginning on February 1, 2023, michiganflora.net will point to this new site.

The new site offers several benefits over the existing website, including real coordinate mapping, giving a clearer view of the density of documentation as well as more precision about plant distributions and their link to landforms. We will also have the ability to update species pages more regularly, both in terms of new collections and as more existing Michigan specimens are georeferenced. In addition, we have a better photo display, and offer indented keys.

Eutrochium

1. Florets mostly (8–) 9–20 (–22) per head; inflorescence flat-topped or of flat-topped subunits; stem distinctly spotted with red-purple or continuously red-purple.

E. maculatum

1. Florets 3–7 per head; inflorescence ± dome-shaped (convex); stem greenish (except at nodes) in common species (purplish in the other).

2. Corollas 5 mm long or less; middle (if not all) internodes ca. (7–) 10–20 mm or more thick, hollow over half their diameter, ± reddish throughout or spotted with elongate red dashes; leaves mostly 6 or more per whorl.

E. fistulosum

2. Corollas 5–6 (–6.7) mm long at maturity; middle internodes less than 5 (–8) mm thick, with solid pith (or a very slender hollow), greenish; leaves 3–5 per whorl.

E. purpureum

All species found in Eutrochium

Eutrochium fistulosumHOLLOW-STEMMED JOE-PYE-WEED 
Eutrochium maculatumJOE-PYE-WEED 
Eutrochium purpureumGREEN-STEMMED JOE-PYE-WEED 

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. January 29, 2023. https://michiganflora.net/genus.aspx?id=Eutrochium.