Thelymitra frenchii, commonly called the scarp sun orchid or Jarrahdale sun orchid, is a species of orchid in the family Orchidaceae and endemic to a small area in the south-west of Western Australia. It has a single long, fleshy leaf and up to three relatively small, blue flowers.
Thelymitra frenchii is a tuberous, perennial herb with a single channelled, fleshy, pale green, linear to lance-shaped leaf NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Up to three blue flowers, NaNsigfig=1NaNsigfig=1 wide are borne on a flowering stem NaNsigfig=1NaNsigfig=1 tall. The sepals and petals are NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. The column is bluish to pinkish, about 5sigfig=1NaNsigfig=1 long and 3sigfig=1NaNsigfig=1 wide. The lobe on the top of the anther is NaNsigfig=1NaNsigfig=1 long and about 2sigfig=1NaNsigfig=1 wide, mostly yellow with a narrow purplish band and a broad, shallow notch. The side lobes have toothbrush-like tufts of white hairs. The flowers remain open even in cool weather and until late in the day. Flowering has only been observed in October.[1] [2] [3] [4]
Thelymitra frenchii was first formally described in 2004 by Jeff Jeanes from a specimen collected near Jarrahdale and the description was published in Muelleria.[5] The specific epithet (frenchii) honours "Christopher (Chris) J. French" for his assistance to the author.
The scarp sun orchid grows in soil pockets on granite outcrops in jarrah forest. It is only known from near Jarrahdale in the Jarrah Forest biogeographic region.
Thelymitra frenchii is classified as "not threatened" by the Western Australian Government Department of Parks and Wildlife.