Echinacea tennesseensis

Taxobox
name = "Echinacea tennesseensis"
status = EN

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image_width = 240px
image_caption =
regnum = Plantae
divisio = Magnoliophyta
classis = Magnoliopsida
ordo = Asterales
familia = Asteraceae
tribus = Heliantheae
genus = "Echinacea"
species = "E. tennesseensis"
binomial = "Echinacea tennesseensis"
binomial_authority = (Beadle) Small

"Echinacea tennesseensis" (Tennessee coneflower) is a flowering plant in the family Asteraceae, endemic to the cedar glades of the central portion of the U.S. state of Tennessee. It is also known as the Tennessee purple coneflower. It is a herbaceous perennial plant growing to 75 cm tall. The leaves are hairy, lanceolate, and arranged in a basal whorl with only a few small leaves on the flower stems. The flowers are produced in a capitulum (flowerhead) up to 8 cm broad, with a ring of purple ray florets surrounding the brown disc florets.

"E. tennesseensis" is a federally listed endangered species and is found in fewer than 10 locations in Davidson, Wilson, and Rutherford Counties. A noticeable characteristic is its generally erect ray flowers, in contrast to the more drooping rays of its most similar congener, "E. angustifolia" (widespread throughout the prairie of the central U.S.) and other common "Echinacea" species such as "E. purpurea".

It has been hypothesized that an ancestral "Echinacea" species spread into middle Tennessee during the hypsothermal period following the last ice age, when conditions were drier and prairies extended into much of the central eastern U.S. that is now forested. As conditions became wetter, the "Echinacea" populations became isolated on the prairie-like habitat of the cedar glades which were eventually surrounded by forest. This isolation resulted in divergence and speciation of "E. tennesseensis".

The Tennessee coneflower was one of the first listed endangered plant species and its recovery has been aided by the purchase of habitat by the Nature Conservancy and the State of Tennessee.

References and external links

[http://www.apsu.edu/baskaufc/Evol48.html Baskauf, C.J., D.E. McCauley, W.G. Eickmeier, Evolution (1994) 48: 180-188]
* [http://www.cas.vanderbilt.edu/bioimages/species/frame/ecte3.htm "Echinacea tennesseensis" images at bioimages.vanderbilt.edu]
* [http://2bnthewild.com/plants/H54.htm Wildflowers of the Southeastern United States: "Echinacea tennesseensis"]