Book Reviews: Wildflowers of the Southeastern United States
ABSTRACT Governmental Land Office records were used to reconstruct the presettlement vegetation of Williamson County, Illinois, about 1807. The vegetation was mapped into four categories, prairie, savannah, and open and closed forest types. Oak-hickory forests were the predominant vegetation occupying 81.2% of the area; savannahs covered 16%, and prairies 2.5%. Savannahs, prairies and open forest were more predominant in the flatter northern 2/3 of the county, while closed forest was most abundant in the southern part where the topography is more rugged. Forest areas supported 109.2 sq. ft. of basal area/acre (24.1M2/ha.) and 64.7 trees/acre (159.8/ha.), and savannah 15.1 sq. ft. of basal area/acre (3.5 M2/ha.) and 6.4 trees/acre (15.8/ha.). Thirty-five tree species were recognized by the surveyors. White and black oaks were the dominant tree species in both forest and savannah. Tests for species association revealed that most species were negatively associated with other species. However, many species were
ABSTRACT A survey of a portion of the Green River Gorge, in Polk County, N. C., was made during 1973-74. The vascular flora includes 557 species, 179 (32%) of which are new county records. The vegetational analysis indicates six forest types correlated primarily with a topographic moisture gradient. From moist coves to dry upper slopes, ridges, and peaks, the corresponding vegetational change is from cove hardwoods or hemlock forests, to oak or oak-pine, to pine-oak or pine. Both floristically and vegetationally, this gorge is similar to the other gorges of the southern portion of the Blue Ridge Escarpment.
ABSTRACT Needle, bud and cone characteristics were measured on 164 trees sampled from natural loblolly-shortleaf pine stands in east Texas. Hybrid index, cluster analysis and principal components analysis were used to characterize the morphological variability of the sample population. Results indicated the existence of two relatively distinct populations (loblolly and shortleaf pine). It was concluded that introgression of loblolly and shortleaf pines is not widespread in the area. Introgression with shortleaf pine has been proposed by several workers as an explanation for the apparent rust resistance of east Texas loblolly pine. In view of our conclusions, alternative explanations include: (1) Ancestral hybridization of the two species has been followed by subsequent speciation and separation; (2) Natural selection of rust-resistant loblolly pine has occurred in east Texas; (3) Unfavorable climatic conditions result in low rust infestation in east Texas, while rust resistance of east Texas loblolly pine when grown in other
ABSTRACT In the past the southern portion of the beech-maple forest has usually been considered to be in a stage in succession toward western and mixed mesophytic forests. A review of the pertinent literature indicates three lines of evidence for this: (1) the reproduction of sugar maple and certain other species often far exceeds that of beech, (2) the presence of young individuals of species characteristic of the mesophytic forests, and (3) the arrangement of the diverse plant communities of topographically dissected sites in a successional series. Our research in one stand of the southern beech-maple forest (Hueston Woods) compared the composition and structure of undisturbed portions with that of areas where the windfall of a large beech had created an opening in the canopy. Key differences found in the subcanopy layers of the closed and open sites indicate a mechanism of beech self-replacement, which, if found in other stands,
ABSTRACT The sedge <em>Eleocharis acicularis</em> (L.) R. & S. is a mat forming species found in acid polluted waters with pH as low as 2.85. Both terrestrial and submergent forms are known and were shown by reciprocal transplants to be genetically identical and freely interconvertible. The colonies tend to be in backwash areas where water current is mostly negligible and substrate texture is clay-silt. Mats buried under silt are capable of reestablishing themselves by internodal elongation in association with the production of new culms. Measurements of the chemical environment varied widely but phosphorus and CO2 levels were thought to be of possible importance. Reproduction is most often accomplished by asexual fragmentation but seeds, when produced, have a germination rate as high as 86%.
ABSTRACT This floristic study treats the 3 species of <em>Psychotria</em> native to Florida. A key to the species is given. Distribution within the state is shown by maps based on county records. <em>Psychotria punctata</em> is recognized as cultivated, but is rejected as a naturalized species.
ABSTRACT Revised distributional records are presented for the ten counties surrounding Highlands, N. C. and include 48 county records and 3 state records. The state records, all of which are very rare, included the species <em>Botrychium matricariaefolium</em> A. Br. and the two hybrids, <em>Dryopteris</em> X <em>neo-wherryi</em> Wagner and <em>D. goldiana</em> X <em>intermedia</em>. The two varieties of <em>Pteridium aquilinum</em> (L.) Kuhn, vars. <em>latiusculum</em> (Desv.) Underw. ex Heller and <em>pseudocaudatum</em> (Clute) Heller, occur intermingled on the same road shoulder yet remain morphologically distinct, providing an excellent opportunity for studies of their isolating mechanisms. <em>Woodwardia virginica</em> (L.) Smith was noted to occur as a single colony covering an area 45 m long and 26 m wide at the widest point. This colony remained sterile for five years until disturbed by a beaver colony and the proportion of the colony which was disturbed suddenly became fertile. These observations provide additional opportunity for field and