Lathrocasis is a recently recognized genus of Polemoniaceae that circumscribes the species first named Gilia tenerrima A. Gray. This species, distributed primarily in the Great Basin and Rocky Mountain floristic regions, has previously escaped thorough taxonomic scrutiny. Surveys of herbarium specimens and living material show that some features of this species have been inaccurately characterized in the past, while other characteristics have not been previously considered in assessing its relationships. Lathrocasis possesses a distinct suite of morphological features that, considered as a whole, distinguish this taxon at the generic level. This suite of characters includes the mostly entire, nonmucronate leaves, effuse branching with diverging to retrorse and threadlike pedicels, uniformity of short stipitate glands throughout, uniovulate locules, spiriliferous seeds with verrucate seed coats, minute funnelform flowers with simple vasculature, and stamens equally inserted approximately mid-tube. Parsimony analyses of ITS, trnL, and matK genes recover similar trees that place Lathrocasis in Gilieae with possible sister relationships to Gilia, a group composed of Allophyllum, Collomia, and Navarretia, or both of these groups combined. A detailed description of L. tenerrima, a review of its taxonomic history, and notes on the type collection are presented.
Johnson, Leigh A. and Weese, Terri L.
"Geographic distribution, morphological and molecular characterization, and relationships of Lathrocasis tenerrima (Polemoniaceae),"
Western North American Naturalist: Vol. 60
, Article 2.
Available at: http://scholarsarchive.byu.edu/wnan/vol60/iss4/2