Here is an article I wrote for the Dec 2007 edition of Castilleja, the newsletter of the Wyoming Native Plant Society:

Spotlight on Lathrocasis tenerrima

By Dave Scott (Kesonie)

Western and central Wyoming mark the eastern extent of Lathrocasis tenerrima (slender gilia) , an interesting and often overlooked species of the Phlox family (Polemoniaceae).    Plants are inconspicuous annuals growing on porous soils and dry slopes at mid elevations, and are often only seen in small and sparse populations.  Individuals are usually less than 30 cm tall and, even in full flower, can be overlooked when you are standing right over them.  Some would call the tiny flowers “precious” or “cute”, but we’ll just stick to the facts; the flowers are usually less than 3 mm in length.

Lathrocasis tenerrima, by Jeanne Janish. From: Hitchcock, C.L., A. Cronquist, and M. Ownbey. 1959. Vascular Plants of the Pacific Northwest, Vol. 4. Posted at eFlora of    

British Columbia.

Lathrocasis tenerrima was transferred from the genus Gilia where it now represents the only species in Lathrocasis (Porter and Johnson 2000; Dorn 2003).   This taxon has been somewhat elusive to taxonomists set on teasing out its best classification.  Asa Gray described Gilia tenerrima in 1870 but its unique characters became apparent when considered against other Gilia in later studies of the group.  DNA analysis in the mid-nineties finally provided additional support to traditional classifications that this species should be split out of Gilia (Johnson and Soltis 1995).  An in-depth study by Johnson and others shortly thereafter cemented the indication that a new genus be constructed for this species.  Lathrocasis tenerrima is now closely allied with Gilia, Navarretia, Collomia, and Allophyllum in the Phlox family (Porter and Johnson 2000).  There are no single distinguishing characters but a combination of nearly entire leaves, downward curved pedicels, and stamens attached near the middle of the corolla tube set Lathrocasis apart from Gilia and other close relatives.

This glandular annual does have an interesting story surrounding the selection of its type locality as well.  It was first vouchered in 1869 by Sereno Watson in the vicinity of present day Evanston, WY.  Johnson and Weese (2000) provide a detailed analysis of the type specimens and locality.  Essentially, the specimen labels and taxon description indicate the types were collected in “Utah, on hills above Bear River, near Evanston.”  The Utah/Wyoming border had just been delineated slightly west of Evanston just a year prior to Watson’s collection.  He referred to this general area as Utah though it had recently been named Wyoming.  Watson’s collecting routes from the geological exploration on which he was working in 1869 were however, shown on maps from the report of that expedition (Watson 1871).   The report shows two collecting routes on hills above the Bear River near Evanston.  The first is a mere 1.5 miles from the town in present-day Wyoming, and the other about 22 air miles from Evanston, but in present-day Utah.  Considering these maps, chances are that the first collecting route was the one referred to in the species description and labels.  Johnson and Weese corroborate this idea that the type locality most likely was in Wyoming (2000).

Lathrocasis tenerrima has gone largely unnoticed in years past but its populations not quite so sparse that it is considered rare.  Wyoming counties where it is common are Fremont, Lincoln, Park, Sublette, and Teton, though it does occur in the state beyond these areas.  This spotlight serves as an encouragement to get out and find new populations of this interesting wildflower.  For this species, Mae West had it right when she was quoted “It is better to be looked over, than overlooked.”

 Literature Cited:

 Dorn, R.  2003. Redrawing the Phlox Family tree.  Castilleja 22(1): 3.

 Johnson, L.A. and D.E. Soltis.  1995.  Phylogenetic inference in Saxifragaceae sensu stricto and

             Gilia (Polemoniaceae) using matK sequences.  Ann. Missouri Bot. Gard. 82(2): 149-175.

 Johnson, L.A. and T. L. Weese.  2000.  Geographic distribution, morphological and molecular

characterization, and relationships of Lathrocasis tenerrima (Polemoniaceae).  West. N. Amer. Nat.  60(4): 355-373.

Porter, J.M. and L.A. Johnson.  2000.  A phylogenetic classification of Polemoniaceae.  Aliso.

            19(1): 51-91.

Watson, S.  1871.  Vol. V, Botany in United States Geological Exploration of the Fortieth

Parallel.  Government Printing Office, Washington.