Reproduction and demography of Townsendia aprica (Asteraceae), a rare endemic of the Southern Utah Plateau

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.     

Horsetails and ferns are a monophyletic group and the closest living relatives to seed plants

Most of the 470-million-year history of plants on land belongs to bryophytes, pteridophytes and gymnosperms, which eventually yielded to the ecological dominance by angiosperms 90 Myr ago. Our knowledge of angiosperm phylogeny, particularly the branching order of the earliest lineages, has recently been increased by the concurrence of multigene sequence analyses. However, reconstructing relationships for all the main lineages of vascular plants that diverged since the Devonian period has remained a challenge. Here we report phylogenetic analyses of combined data--from morphology and from four genes--for 35 representatives from all the main lineages of land plants. We show that there are three monophyletic groups of extant vascular plants: (1) lycophytes, (2) seed plants and (3) a clade including equisetophytes (horsetails), psilotophytes (whisk ferns) and all eusporangiate and leptosporangiate ferns. Our maximum-likelihood analysis shows unambiguously that horsetails and ferns together are the closest relatives to seed plants. This refutes the prevailing view that horsetails and ferns are transitional evolutionary grades between bryophytes and seed plants, and has important implications for our understanding of the development and evolution of plants.