The genus Carex is made up of about 2000 species of herbaceous perennials occurring in a wide range of habitats throughout the world but especially in north temperate and arctic regions. They are modular organisms that reproduce vegetatively by rhizomes or other means, some species forming extensive and long-lived clones, others tufts, clumps, or tussocks of various sizes. Most temperate and arctic species have shoots formed during the previous year, some emerging in autumn, others remaining below ground until spring. The maximum shoot life span for temperate species appears to be approximately 24 months but mortality is very high; sometimes 90% of shoots do not live for the whole 2-year life span. Snoots in arctic-alpine regions live longer, perhaps as long as 5–7 years, with lower mortality. Mortality is caused by differences in time of emergence, flowering, animal grazing, the age of the genet, and internal competition through the rhizome system.

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We compared seasonal growth patterns and nutrient (N, K, Ca, Mg, Fe, Mn, Cu, Zn, Pb) uptake of Phalaris arundinacea in an unpolluted wetland (Ithaca site) to those growing in a constructed wetland (Fenton site) receiving landfill leachate. Winter aboveground living biomass was higher at Fenton than at Ithaca probably owing to the longer growing season at Fenton caused by the warm leachate, which averaged 4-8*(2 during the winter. Uptake of nutrients was also greater at Fenton, with aboveground and belowground N uptake by plants approximately 35 g m -2. Such uptake means that P. arundinacea over the total area of the beds may utilize about 10% of the yearly N input and lesser amounts of other nutrient elements.

Seasonal changes in above— and below—ground standing crop and primary production in a Carex rostrata wetland and an adjacent dry Poa pratensis old field were determined. Above ground, the Carex rostrata standing crop of green material varied from a minimum of 114 g/m2 frozen in the winter ice to a high of 852 g/m2 in late August. Maximum daily production averaged about 11 g/m2° day from mid—June to mid—July. Below—ground standing crop was highest in winter at 328 g/m2 in late July. Below—ground standing crop then increased at a rate averaging about 1 g/m2#?day. Poa pratensis growth was rapid in early spring, the green above—ground standing crop peaked at 114 g/m2 in late May—early June. A definite midsummer cessation of growth then occurred, the average summer standing crop averaging jut 87 g/m2during July and August. A second greater peak of production then occurred with a maximum standing crop of 149 g/m2 reached in late September. The daily production rate at this maximum was 3.3 g/m2°day. Below ground the standing crop in the 0—20 cm level was at the season's high of 1667 g/m2 in winter and then declined to an average summer low of 1194 g/m2 after which it rose to 1458g/m2 in late October.