An unexpected concentration of calcicole mosses and lichens has been discovered at and near a small spring seep on the granite headwall of the North Basin of Mt. Katahdin, Piscataquis County, Maine. Water samples from the spring were circumneutral and high in calcium ion content, whereas other springs, ponds, and streams on the mountain tested acidic and low in calcium. Because the Katahdin granite contains no primary carbonate minerals, it is suggested that the source of calcium enrichment in the North Basin spring water is secondary calcium carbonate (calcite) precipitated in cavities and fractures near the base of the upper Katahdin granite and its subsequent dissolution and mobilization by percolating groundwater. Plagioclase, epidote, and other calcic minerals in the granite supply the primary calcium ions. The moss calcicoles grew in small discontinuous patches on wet humified peaty soil over alpine bedrock ledges in communities having floristics and water chemistry similar to lowland rich fens. Present in or near the seep were mosses previously unrecorded for New England or Maine [Loeskypnum wickesiae (Grout) Tuom., Neckera oligocarpa Bruch in Hartm., Pseudoleskea radicosa (Mitt.) Mac. & Kindb., Tortella tortuosa var. fragilifolia (Jur.) Limpr., Warnstorfia sarmentosa (Wahlenb.) Hedenäs], one lichen [Hymenelia cyanocarpa (Anzi) Lutzoni], reported here for the first time from North America, and another lichen (Thelidium minutulum Körb.) for the first time from the contiguous United States. An area adjacent to the seep, but unaffected by calcareous seep-water, was remarkable for a concentration of rare lichen species of acidic rocks, including Catillaria contristans (Nyl.) Zahlbr. and Lecanora caesiosora Poelt, that have not previously been reported from North America. The bryophyte and lichen flora of the seep area is an example of a Holocene alpine microrefugium. Refugia such as these can serve as a source of propagules that allow new populations to establish elsewhere in mountainous terrain, or beyond, during climatic and other environmental change. Therefore, extant, cryptic microrefugia are important biogeographically and especially worthy of preservation efforts.

Five infraspecific taxa have been recognized in Cymopterus glomeratus (= C. acaulis): vars. glomeratus (= acaulis), fendleri, greeleyorum, higginsii, and parvus. The results of previous phylogenetic analyses of DNA sequence and morphological data have supported the close association of these five varieties, although the relationships among them could not be discerned. The recognition of infraspecific taxa within C. glomeratus is controversial. Multivariate analysis of variance and principal component analysis of 288 specimens representing the morphological variability and geographic distribution of this species complex were conducted to test the validity of these infraspecific taxa. Results show that most of the characters previously used to recognize these varieties are highly variable within the taxa. Although analysis of variance demonstrated some statistical differences among the varieties, patterns were not consistent. No clearly separated clusters are revealed in the principal component analysis and all five varieties were intermixed on the plots of the principal components. On the basis of the results of both phylogenetic and multivariate analyses, we propose that plants in this species complex be recognized as one species, C. glomeratus, with no varieties. The nomenclature and typification of this species are presented.

The vascular plant community in a freshwater tidal wetland on the lower Connecticut River was studied in 2000. The effects of abiotic conditions on density and species density of plants in 70 samples, each 0.25 m² in area, were characterized. Sixty species were recorded. The mean species density was highest in shallow water because the number of emergent species in the community was far greater than the number of submerged species, which occurred with higher frequency in deeper water. Plant density had a bimodal distribution because of the different responses of emergent and submerged plants to water depth and was lowest in shallow water, where physiological stress, physical disturbance, and possibly herbivory are suspected of being limiting. Ordination and regression analyses found that water depth and the amount of organic matter and nitrogen in the sediment had the greatest effect on wetland plant density, although other variables also were influential. Abundance of emergent and submerged species differed in their responses to ammonium and nitrate levels. Overall species density was most strongly correlated with water depth. Several plant associations, including associations of submerged and emergent species, were identified, based on shared affinities for environmental conditions.

The genus Diodella of Small is not synonymous with Hedyotis § Diodella as is indicated in Index Nominum Genericorum. The two taxa have different nomenclatural types and belong to different tribes of the Rubiaceae. The first mentioned has a single seed in each locule and the second has many seeds. The stipules and seeds also differ markedly. Consequently the spermacocoid genus Diodella (typified by the type of Diodia rigida) is strongly distinguished from Hedyotis § Diodella [typified by the type of Hedyotis boscii DC. = Oldenlandia boscii (DC.) Chapm.] by many significant morphological features and should not be confused with it. The type of Small's genus Diodella is the type specimen of D. rigida, a perennial species not known to occur in the United States, although mistakenly included by Long and Lakela as well as by Small. The closely related but annual Diodella teres is common and widely distributed throughout much of the eastern United States, Mexico, Central America, and the Greater Antilles as well as tropical South America. The perennial Diodella rigida (= Diodia apiculata K. Schum.) is found in southern Mexico and throughout much of Central America, the Antilles, and northern and eastern South America. Possibly a case could be made for conserving Diodella with a new type—from a species that both occurs in southern Florida and is an annual as specified in the protologue. However, conservation seems both unnecessary and undesirable since there are at least two validly published and available generic names with priority over Diodella.