Townsendia aprica (Asteraceae: Astereae), a rare pulvinate perennial of the Southern Utah Plateau, was listed as threatened under the U.S. Endangered Species Act in 1985. Here we report on the reproductive biology and pollination of this little-known species and provide an estimate, for a single site-year, of size-specific reproductive effort. Last Chance townsendia appears a short-lived perennial that begins reproducing in its 2nd year (1.5–2.0 cm diameter). Maximum reproductive effort is attained with the 2.5–4.0 cm diameter size class: 38% of these plants produced 84% of the flower heads. Few plants survived past the 4-cm size class. The species is primarily self-incompatible: neither autogamous nor geitonogamous breeding system treatments produced a significant number of achenes. Unlike some populations of some congeners, the Ivie Creek population was not apomictic. Outcrossing is the primary means of reproduction and native solitary bees are the most important pollinators. Paramount are several species in the genus Osmia, and the ground-nesting species Synhalonia fulvitarsis, which nests among the T. aprica plants. Synhalonia fulvitarsis also visits a contemporaneous blooming phlox (P. austromontana), which may facilitate pollination of the rare townsendia. The Townsendia-Phlox-Synhalonia interaction may represent another example of why we must consider communities rather than individual species in our conservation efforts.
Tepedino, Vincent J.; Sipes, Sedonia D.; and Griswold, Terry L.
"Reproduction and demography of Townsendia aprica (Asteraceae), a rare endemic of the Southern Utah Plateau,"
Western North American Naturalist: Vol. 64
, Article 6.
Available at: http://scholarsarchive.byu.edu/wnan/vol64/iss4/6