Poster

         Floristics & Taxonomy

A Morphological Delineation of Pediomelum aromaticum

Presenting Author
Lark Earl
Description
Pediomelum aromaticum or aromatic breadroot, is a rare member of the Fabaceae native to southeast Utah and the adjoining parts of Colorado and Arizona. Some botanists recognize three varieties within P. aromaticum: var. tuhyi, var. barenyi, and var. aromaticum (e.g. S.L. Welsh, the Utah Flora). Other botanists recognize only a single taxonomic unit (e.g. Jim Grimes’ 1990 monograph of Psoraleeae). A definitive understanding of the species and variety limits in this species complex is important to conservation management being done by federal and state entities, as its circumscription into three varieties has implications for its recognition as a rare, sensitive, or threatened taxon. To more objectively delineate this species complex, in this study, morphological characteristics were selected from various botanists’ descriptions and dichotomous keys of this species and its varieties. Eleven characters, including flower, calyx, tube, lower tooth, bract, peduncle, pedicel, stipule, and petiole lengths as well as terminal-to-lateral petiolule and first-to-second branch ratios were measured using ImageJ on digital images of herbarium specimens available through the Intermountain Region Herbarium Network. Specimens that were not previously identified to variety were identified by using the key in the Flora of Utah sensu S.L. Welsh’s circumscription. The resulting measurements were analyzed using multivariate morphometrics to delineate the amount of variation and its distribution across taxonomic varieties and provide a sense of whether varieties are warranted. This research was done to enable commentary on the conservation efforts of this plant.