Sunday, June 30, 2013

Early Summer in the Prairie

Late last summer, I visited a site near Lowell in Lake County, Indiana and unexpectedly stumbled into a dry-mesic prairie opening with good diversity and unique species including Asclepias viridiflora, Aster laevis, Ceanothus americanus, Eryngium yuccifolium, Liatris scariosa var. nieuwlandii, and Petalostemum purpureum.  I had a chance to get back to the site a few weeks ago.
Dry-mesic Prairie Remnant with an abundance of Silphium terebinthinaceum
In northwest Indiana into Illinois, it is not uncommon to see Silphium terebinthinaceum along roadsides... an indication of the prairie that once was.  In most cases, this is one of the only natives that remains, with Solidago rigida and Ratibida pinnata sometimes holding on as well.  In the case of this site, a rich prairie flora has persisted in this remnant despite lack of intentional management.

Lobelia spicata
One of the plants that I noted in this remnant last summer that was in bloom a few weeks ago was Lobelia spicata; it should continue to flower into late August, but its inflorescences get a bit twisted later in the season.  This is primarily a prairie, savanna, and glade species of eastern North America.  Its flowers look similar to those of Lobelia kalmii, a species of wet, calcareous soils, but the leaves of Lobelia kalmii are less than 3 mm wide, whereas those of Lobelia spicata are more than 3 mm wide.

Parthenium integrifolium was also beginning to bloom when I was at the prairie this summer and should continue to bloom into mid-September.  This composite grows in prairies, savannas, and glades and doesn't tolerate site degradation.  It has been used to make a tea to treat fevers (hence one of its common names, American Feverfew), and was also used to treat malaria.  A similar species, Parthenium hispidum, is known from the central United States.  It has stems with noticable speading hairs, upper leaves that are auriculate-clasping with spreading hairs on the veins beneath, and larger flower heads.  Parthenium integrifolium has stems that are glabrous to minutely pubescent, upper leaves that are sessile but not clasping with mostly appressed hairs on the veins beneath, and smaller flower heads.  Flora of North America treats these both as Parthenium integrifolium, not even warranting varietal status to Parthenium hispidum.  Having seen both, this surprises me.
Parthenium integrifolium
Nearby is a railroad prairie remnant that I also surveyed in 2012.  Interesting prairie plants at this location included Allium cernuum, Comandra umbellata, Dodecatheon meadia, Heuchera richardsonii, Phlox pilosa, Silphium integrifolium, Veronicastrum virginicum, and Zizia aurea.  I also noted the remains of an Oenothera that I was able to verify this summer.

Oenothera fruticosa
Oenothera fruticosa is identified by its winged, glandular pubescent ovaries and its large petals.  It is a showy prairie species with a range including much of eastern North America.  The very similar Oenothera pilosella, which lacks glandular hairs on its pubescent ovaries, is sometimes found growing with this species, and it can be difficult to distinguish between the two.

Prairies reach their full glory late in the season, but there is plenty to see early in the summer as well.