Tuesday, October 12, 2010

Liatris, the "Star" of the Prairies

As spring starts to fade and gets swallowed by the hot, steamy months of summer, wildflowers begin their move from woodland sanctuaries to the open, sunny fields and prairies.  While a number of species continue to thrive and bloom on the forest floor and woodland borders/openings throughout the year, many more need larger amounts of sunlight the closed forest canopy cannot provide.

Lynx Prairie in Adams County

Hailing from the largest family of vascular plants, Asteraceae or Compositae, the genus of Liatris has to rank near the top of my favorite summer wildflowers.  Seven species are indigenous to Ohio's soils and all are beautiful and unique in their own ways.  The many small prairie openings in Adams County, OH are home to five species of Liatris and provided me many opportunities to see these plants in their natural habitat.  Some species are grown in nurseries and wildflower gardens so a few of you may recognize these plants from those experiences.  Let's take an inside look at some of the charming members of this intricate genus.

Liatris squarrosa
Liatris squarrosa

Scaly Blazing Star (Liatris squarrosa) is one of two species of Liatris that are state listed with this particular one falling under the potentially threatened status.  While only found in a handful of Ohio counties, this species shows no geographical distribution preference, being found in all quarters of the state except the far southeast.  Blooming and fruiting from July - October, this plant is found growing in xeric prairies, rocky open woodlands and barren Oak savannas; all having poor soil conditions in common.  The inflorescence (whole flower cluster) of this species lies at the top of the stem as well as singly in the leaf axils and is made up of 15-60 disk flowers (single, pink flower).  The single disk flowers remind me of a tiny, pink snake 'tasting' the air with its tongue-like stamens.  One of the best means of keying these plants down to the species level is taking a close look at the involucre (the rosette of bracts the inflorescence emerges from; essentially the area between the inflorescence and where it attaches to the stem).  The shape, color and glabrous (smooth) or pubescent (hairy) nature of the bract helps tremendously.  With L. squarrosa the bracts have a telltale appearance of coming to a sharp point, scaled structure (hence the common name) and being covered in hairs.  While the pubescence can vary greatly in this species, all the plants I came across showed a heavy amount.

Liatris squarrosa white variation

The above picture is of a lone white flowered variation of L. squarrosa.  In the multiple prairie openings, out of the hundreds and hundreds of plants in bloom this was the only white one I saw.  How rare and unique it is I'd love to know.

The other state listed species is the threatened Cylindrical Blazing Star (Liatris cylindracea) which I was fortunate to come across but did not have my camera equipment with me.  It can be found blooming around the same time and in the same habitat as L. squarrosa and has a similar plant/flower structureThe best means of I.D.'ing this species in the field is once again looking at the involucre.  The smooth cylindrical surface constructed from the green bracts along with the long and narrow nature of the involucre make for positive identification.

Liatris aspera
Liatris aspera

Next up is my favorite of the group, Rough Blazing Star (Liatris aspera).  Much more common in the state than the previous species, this guy is still mostly restricted to the southern third of Ohio and some populations up along Lake Erie in the sand dune areas.  Why it is largely absent from the northern two thirds of Ohio is unknown despite suitable habitat being available.  This beauty blooms later in the season (August-September) in the same habitat and environments as just about all Liatris'.  With such robust and full blooms as shown in the photograph on the left, this plant will commonly droop over from the weight.  Similar to the species above the involucres are key to identifying this species along with the much shorter and less emergent disk flowers.  Taking a look at the bracts (seen in the photograph on the right), they are circular in fashion and around the edges, especially at the apex, are a pinkish/white color.

Liatris spicata
Liatris spicata with Tiger Swallowtail

The last species I would like to discuss is the Spiked Blazing Star (Liatris spicata).  Our most common and widely distributed Blazing Star it differs from the all the previously mentioned species in a couple different ways.  Instead of growing in xeric conditions this species prefers moist soils of all types of habitats.  I've seen in it prairies, marshes, fens and wet meadows/fields.  Also different is the appearance of the plant itself.  A tall, straight stem is covered with much smaller inflorescence's that contain fewer disk flowers per bundle.  Something interesting within the Liatris genus is the fact that it flowers from the top down (as shown in the photograph on the left.  The top most flowers have wilted while the bottom is still healthily in bloom), while many, many other plants bloom the traditional bottom up.  Blazing Stars are a huge hit with the butterfly crowd as well as the human.  As seen above an Eastern Tiger Swallowtail is making good use of the nectar from L. spicata.  Watching these guys start at the bottom of the stalk and work their way up, taking the time to sample each disk flower with their long proboscis is something I could watch all day.  The insect-plant interactions I witness on an almost daily basis never get old.  Such an amazing world that goes on right under our noses with a very large majority never taking the time to care or notice. 

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