A Revision And Systematic Evaluation Of Piper Subgenus Arctottonia (piperaceae) (mexico, Pollination, Phylogenetic (cladistics)).

Taxonomic concepts within the Piperaceae have been a major problem since the family was first monographed by Miquel (1843-44). This difficulty has been particularly evident for the genus Piper. Early attempts to segregate taxa from Piper sensu lato concentrated on seemingly significant floral features such as stamen and stigma number, bract morphology, and inflorescence development. The question of the taxonomic significance of these features and the lack of a stable, universally accepted subclassification for Piper prompted the present study of Arctottonia, a species complex that was in need of revision. Arctottonia is easily distinguishable among pipers by the combined presence of palmately-veined leaves and racemose inflorescences. The group is neotropical, ranging from west-central Mexico to Panama; it is, however, predominantly a Mexican assemblage. Information from anatomy, morphology, cytology, ecology, and pollination biology is used. Evolutionary relationships and character trends are analyzed resulting in a preliminary phylogenetic tree. Keys to the tribe Pipereae and subgenus Arctottonia are presented. Sixteen species are described, including seven new to science. This revision represents the first comprehensive treatment of these taxa since Trelease (1930) formally established Arctottonia at the generic level. It is not believed that the characters upon which Trelease segregated Arctottonia warrant recognition at the level of genus. Basic floral morphology and factors controlling the production, release, and dispersal of pollen suggest anemophily in Piper subgenus Arctottonia. Field observations of two species indicate that several insect species can transport piper pollen and may act as pollen vectors. It is suggested that wind and insect pollination may be operating together, or possibly that the present period represents a transition from one system to the other. The genetic implications of combining anemophily and entomophily are discussed as well as the reasons why such a system might develop.PhDBiological SciencesBotanyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/127794/2/8600412.pd