Siphium trifoliatum

Above is a photo of Silphium trifoliatum at the main prairie.  The main prairie contains many of these plants but most years only a few of them will bloom.  This year I have counted 15 blooming plants at Big Hollow's Main Prairie. Deer herbivory on this Silphium population has always been voracious, but this year the deer seem to have held back a bit.  I will guess that this can be attributed to two changes from the previous seasons.  Wetter weather (up until July) has increase plant biomass, but also clearing the woodlands surrounding the prairies of exotic shrubs and vines has removed a lot the cover the deer need to feel secure in the area.  Clearing the surrounding woods has been a win-win situation for the Silphiums at Big Hollow, reducing deer herbivory and releasing many established plants from deep shade.

July 18,2012

Variegated Fritillary (Euptoieta claudia)

Harry Henderson sent this great picture of a variegated fritillary at Big Hollow.  He explained that the variegated's are fairly uncommon for the area and are not seen every year.  Also this species is not a resident, as it invades northward from its permanant range in the south each summer.

Cirsium pumilum

I'm glad to report that the Cirsium pumilum population at big hollow is expanding.  This year has produced more flowering plants since the restoration began.  Presently it is range is limited to two smaller disjunct prairies within the Big Hollow restoration area.  If things continue to go well for these thistles this year I should be able to collect a good bit of seed to spread around the main prairie at big hollow.  Pollinators should greatly benefit from this population expansion of this native thistle as it has an earlier phenology than the already well establish native Cirsium discolor.  

A veiw of the upper section of the Main Prairie from the woods.

A view of the lower end of the main prairie.

The main prairie at big hollow appears to be more flowers than grass at this point in the season.  Part of the reason for this abundance of blooms is that that flowering forbs have colonized most of the cleared and restored areas faster than the prairie grasses.  In the above photo, the left half of the frame contains a stable grassland that was present before I started the restoration project.  The right half of the frame was mostly covered by autumn olive canopy four years ago.  This side does indeed contain all the grasses found on the left although at a reduced density.  I think that as time goes on the right side will become grassier.  But for time being I will enjoy this garish display.

The growing season so far has been favorable for plant growth at Big Hollow.  Things are starting to get a bit dry now but June and May brought a good bit of moisture to the hollow, resulting in taller plants and in some cases more profuse flowering.  A visit to Big Hollow today revealed many of the prairie's showiest flowering plants at or close to their peak floral phenology.

Monarda fistulosa

Asclepias viridiflora

Some of the green milkweeds at big hollow have been blooming for a couple of weeks now.  There is an abundance of blooming green milkweed this year making me hopeful for a large seed crop.

Solanum carolinese

 The heavily rhizomatous horse nettle has beening spreading through a section of the main prairie and has been blooming for weeks now as well.

Scutellaria incana

The Hoary skullcap has just recently started blooming here. In fact, this individual appears to be the first in bloom.  The plants closer to the woodland edges have yet to reveal their purple-blue flowers.

Asclepias purpurascens

 

I was delighted to find a single flowering purple milkweed stem at the mesic prairie at Big Hollow recently.  Purple milkweed is uncommon throughout much of its range, including here in Pennsylvania.  

Unfortunately I don't think this plant will produce seed without another individual to exchange pollen with.  Hopefully there are other purple milkweed plants in the area, still gaining size and vigor, which will bloom next year.