Garrett E. Crow

Species diversity in aquatic angiosperms: latitudinal patterns

Abstract Preliminary studies of aquatic plants in numerous tropical aquatic habitats in Costa Rica indicate a low level of diversity, and such a level of species richness appears to be in direct conflict with the general viewpoint that tropical ecosystems are exceedingly diverse. Furthermore, there is a strong tendency for dominance of particular plant species within tropical aquatic ecosystems, whereas in tropical forest ecosystems, individuals of a species tend to be scattered rather than to express dominance. A comparison of aquatic plant diversity on a latitudinal basis reveals a higher level of diversity at warm temperature latitudes and a surprisingly high, if not highest, level at cool temperature latitudes. This appears to be true when comparing representative aquatic families as well as aquatic habitats. Standardized data on biodiversity in aquatic ecosystems are needed for further comparative purposes. Additionally, aquatics are poorly known for tropical regions; thus, there is a great need for field work to be conducted in aquatic habitats of the tropics.

Phylogenetic relationships in Nuphar (Nymphaeaceae): evidence from morphology, chloroplast DNA, and nuclear ribosomal DNA

The genus Nuphar consists of yellow-flowered waterlilies and is widely distributed in north-temperate bodies of water. Despite regular taxonomic evaluation of these plants, no explicit phylogenetic hypotheses have been proposed for the genus. We investigated phylogenetic relationships in Nuphar using morphology and sequences of the chloroplast gene matK and of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA. Two major lineages within Nuphar are consistently resolved with the morphological and molecular data sets. One lineage comprises New World taxa and the other represents a primarily Old World lineage. Relationships within the major lineages were poorly resolved by morphology and ITS, yet certain relationships were elucidated by all analyses. Most notable is the strong support for a monophyletic lineage of dwarf taxa and the alliance of the North American N. microphylla with the Eurasian taxa. Minor discordance between the independent cladograms is accounted for by hybridization. The common taxonomic practice of uniting all North American and Eurasian taxa under one species is not supported phylogenetically.

Evidence for the hybrid origin of Nuphar×rubrodisca (Nymphaeaceae)

Plants intermediate in appearance between Nuphar microphyllaand N. variegata (Nymphaeaceae) have long been assumed to bethe result of hybridization. The evidence for this is based primarilyon field observations of morphology, poor fruit production, closegeographical proximity of presumed parent species, and limited pollensterility data. Fertile populations of the same plants have also beendocumented. We employed multivariate analyses of morphology, pollenfertility studies, and random amplified polymorphic DNA (RAPD) markersto test the hypothesis that Nuphar × rubrodiscarepresents a natural interspecific hybrid between N.microphylla and N. variegata. Examination of 15morphological characters demonstrated the intermediacy of N.× rubrodisca between N. microphylla and N.variegata, and the pollen data revealed a markedly lower meanpollen viability in N. × rubrodisca (23%)compared to the other two species (91 and 86%, respectively). Eight 10-mer primers produced 13 species-specific RAPD markers forN. microphylla and nine for N. variegata, with all 22markers present in N. × rubrodisca. The datafrom RAPDs are concordant with morphology in implicating N.microphylla and N. variegata as parents of N.×rubrodisca.

The systematic significance of seed morphology in Sagina (Caryophyllaceae) under scanning electron microscopy

The seed morphology of 15 species ofSagina from North America, Europe, and eastern Asia was studied, utilizing the scanning electron microscope, to determine the significance of seed coat features as taxonomic characters. There is variation in particular surface features within some members of the genus. However, superficial ridges and tubercules exhibit patterns very helpful in determining relationships among some species. Two basic seed types occur in the genus and are diagnostic at the sectional level. The saginoid seed, characteristic of sectionSagina, is obliquely triangular in outline, is grooved along the two dorsal ridges, and has slightly concave lateral surfaces. The crassuloid seed, characteristic of sectionMaxima, is obliquely reniform in outline, lacks dorsal grooves, and has shallowly convex lateral surfaces.

Isozyme variation and population structure in Podostemum ceratophyllum Michx (Podostemaceae) : implications for colonization of glaciated North America

Abstract Podostemum ceratophyllum Michx is the only New World member of the primarily tropical Podostemaceae to reach into temperate regions. Isoenzyme studies of 11 populations from eastern North America indicate that genetic diversity is partitioned differently within and among populations north (genetically uniform) vs. south (genetically diverse) of the glacial boundary. Colonization by few genotypes subsequent to glacial retreat is suggested as an explanation for the occurrence of few genotypes among northern populations. Allozyme diversity within southern populations suggests a significant level of outcrossing, contrary to prior reports.

Myriophyllum quitense Kunth (Haloragaceae) in Bolivia: A terrestrial growth-form with bisexual flowers

Abstract A terrestrial growth-form of Myriophyllum quitense growing in a lake bed in the interandean valley region of Bolivia represents the first report of a terrestrial growth-form for this species. While typically M. quitense possesses leaves and flowers in whorls of (3–) 4, this population is noteworthy for possessing 2–5% of individuals with both leaves and flowers in whorls of five, and for the presence of bisexual flowers. Observations regarding the distribution, habitat preferences and intraspecific variation of M. quitense in Bolivia are also given.

Potamogeton×haynesii (Potamogetonaceae), a new species from northeastern North America

Potamogeton×haynesii is described as a new species from northeastern North America. The nameP. longiligulatus has been misapplied to this plant. Following the study of type material,P. longiligulatus is placed in synonymy underP. strictifolius.

Foreign Plant Stock: Concerns for Wetland Mitigation

existing gene pools. While analyzing the floristicomposition and plant species richness of created wetland ecosystems of southeastern New Hampshire, we made several observations on the methodology of vegetation composition planning, and how particular plant species are selected and become incorporated into mitigation projects. The outcome of this investigation (Padgett, 1993; Padgett and Crow, in press a; Padgett and Crow, in press b), along with a review of the subsequent literature, has evoked questions concerning the revegetation strategies, vegetation sources, and resultant floristic compositions of created wetland ecosystems. The following discussion is an attempt to bring to focus these questions and concerns.

The Flora and Vegetation of Timber Island, Lake Winnipesaukee, New Hampshire, U.S.A

Abstract The vascular flora of Timber Island, the largest undeveloped island in Lake Winnipesaukee, New Hampshire, was surveyed, and a vegetation analysis conducted. The island was found to have 187 vascular plant species, none of which are listed as rare or endangered for the state. The combination of tree species found throughout Timber Island indicates a forest type characteristic of the Central New Hampshire region. In the vegetation analysis, abundance and frequency data were recorded from 106 study plots and analyzed using a two-way indicator species analysis program (TWINSPAN). Six cover types (CT) were defined: Pinus strobus–Gaylussacia baccata CT, Fagus grandifolia–Ostrya virginiana CT, Pinus resinosa–Gaylussacia baccata–Vaccinium angustifolium CT, Tsuga canadensis CT, Acer rubrum–Dulichium arundinaceum CT, and Ruderal CT. Two additional cover types were recognized through qualitative field observation alone: Shoreline CT, and Vernal Woodland Pool CT. While not included in the floristic analysis, twenty-four bryophyte species were documented on the island, 15 of which are new records for Belknap County. A modified Line Intercept Analysis, employed to quantify ground cover, showed that herbaceous plant and bryophyte cover was sparse (7% each), with duff and leaf litter covering 74%, exposed rock outcrop 8%, vernal pools 3%, and 1% disturbed or bare soil. Soil analysis revealed a weak correlation with cover type. Two indices of similarity, Sørensens Index and the Simple Matching Index, were utilized to compare the vascular plant flora of Timber Island to three other island floras in Lake Winnipesaukee: Rattlesnake Island, Bear Island, and Three Mile Island. Sørensens Index showed a 50.0% similarity with Bear Island, 51.1% with Rattlesnake Island, and 52.7% with Three Mile Island. The Simple Matching Index showed higher levels of similarity: Bear Island, 51.66%; Rattlesnake Island 59.51%; and Three Mile Island 65.59%.

Floristic reevaluation of a created wetland in Portsmouth, New Hampshire

Abstract Long-term reassessment of floristic diversity in created wetlands is needed to gain an understanding of how wetlands created for mitigation mature floristically. A thorough floristic survey of a 17-year old created wetland in southeastern New Hampshire was conducted to compare current data to a 1992 floristic study of the site. The flora in 2002 included 110 species, whereas the total number of species recorded in 1992 was 101. Not only had diversity increased, but the flora had changed in a 10-year span; the floristic lists of the two years showed 79 shared species. Sørensens Index of Similarity revealed a floristic similarity of 75%. Carex atherodes, new to the site in 2002, represents a new state record for New Hampshire. As there is a great need for long-term evaluation of mitigation wetlands, these data contribute toward a better understanding of the maturation of created wetlands, and can be used to make more meaningful floristic comparisons with natural wetlands and evaluate the long term success of wetland mitigation projects.