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Phacelia ranunculaceasensu lato (subgenus Cosmanthus, Hydrophyllaceae) occurs on floodplains and in alluvial hardwood forests throughout eastern North America. It is comprised of herbaceous annuals with alternate, pinnate leaves and white to lavender, tubular-campanulate flowers in terminal scorpioid-like cymes. The distribution of populations displays a disjunct between the Midwest and Atlantic coastal plain, with a chromosome number of n = 6 associated with the former and n = 14 allied with the latter. A phenetic analysis of morphological characters was conducted using 350 herbarium specimens examined from 21 herbaria. The resulting phenogram revealed two distinct clusters of specimens that correspond to the haploid chromosome numbers. Correlation of the clusters and chromosome counts with type specimens resulted in recognition of two taxa: Phacelia ranunculaceasensu stricto and Phacelia covillei. Results of morphological analyses, a diagnostic key, species descriptions, and lists of representative specimens are provided for these two closely related species.
The Australian punk tree Melaleuca quinquenervia is a notorious invasive weed that threatens the biological integrity of Florida's Everglades ecosystems. A comprehensive plan initiated to manage M. quinquenervia includes an ambitious biological control program, and as part of this program we investigated the origins and invasion history of M. quinquenervia in Florida. Scrutiny of public and private records showed that extant populations derive from more than a dozen introductions, with the earliest occurring during 1886 in Sarasota County. Six sources, some Australian and some extra-Australian, have contributed to Florida's populations. The tree became naturalized in southern Florida during the 1920s, but a paucity of records makes it difficult to determine when naturalized populations began to proliferate via an exponential growth phase. Human distribution of seeds and seedlings is a confounding factor in attempting to decipher rates of M. quinquenervia invasion.
Managing rare endemic plants often requires an understanding of their reproductive ecology. We investigated pollination biology, seed set, seed dispersal, and seedling recruitment of Rudbeckia auriculata (Asteraceae), a species endemic to the Southeastern United States. Based on observations of pollinator abundance and pollen load on floral visitors, the most likely pollinators are primarily native bees, particularly Andrena aliciae Robertson in medium and large populations of R. auriculata, and Halictids in small populations. Seed set varied from 0.24% to 16.9% in small populations (<40 flowering stems) and from 26.5% to 31.4% in medium (40-999 flowering stems) and large (1000 flowering stems) populations, with significantly lower seed set in the small populations. Exclusion of visitors from inflorescences showed that, like many members of the Asteraceae, R. auriculata is probably self-incompatible. Seed dispersal appears to be highly localized and dependent upon gravity. Seedling recruitment is poor, particularly when the soil is covered with litter or when the species is in competition with others.
The northernmost record of Rhizophora mangle (red mangrove), recently vouchered from Fort Matanzas National Monument in St. Johns County, Florida, is discussed in reference to the ecology, morphology, and preservation of the species.
A survey for myxomycetes was conducted within the Radnor Lake State Natural Area, Davidson County, Tennessee from May 5 to October 2, 1994. Fruiting bodies that developed on samples of bark and plant debris placed in moist chamber cultures were used to supplement field collections. The present report deals with 225 specimens representing 57 species of myxomycetes. Three of these (Diderma floriforme, Physarella oblonga, and Comatricha longa) are new reports from Tennessee.