by Carl Strang
Though the friary site at Mayslake Forest Preserve has begun to develop some prairie vegetation, there still were plenty of weedy annuals in last year’s growing season. One of the more abundant was horseweed, a tiny-flowered relative of the fleabanes (though some botanists remove it to another genus, Conyza). There are two forms of this plant up on that plateau, so different that they appear to be different species at first. One shows the open tops characteristic of horseweed.
Here is a horseweed in bloom, for comparison.
Zooming in on the individual winter fruiting structures, we see that the seeds are gone.
A few scattered plants at first glance look much different.
The stems are thicker, but otherwise identical to those of the taller, more open plants.
The branching tops are compressed together.
Zooming in on these, the individual fruiting structures show the biggest difference from the normal plants.
I wonder if a fungal or viral disease might have hit these darker, club-like plants. The flowers appear abortive, and everything else seems to say that they are indeed horseweeds. Here is another item to tuck away in memory and watch for during the coming growing season.