Inland beach occurs on the margins of seepage lakes where specialized vegetation adapted to fluctuating water levels occurs. Water levels may vary as much as six feet or more over a few years or decades, favoring annuals, short-lived perennials, and other species adapted to both high and low water.
The vegetation of the inland beach community typically grows in three distinct vegetative zones-the lower inundated portion, the damp-to-saturated middle beach, and the higher, drier upper beach. While species composition varies across the state, suites of species (families, growth forms) represented in each zone are relatively consistent. Important plant species in the inundated lower beach zone include a number of graminoid emergents such as spike-rushes (Eleocharis spp.), bulrushes (Scirpus spp. and Schoenoplectus spp.), and horsetails (Equisetum spp.). The damp middle beach zone can support diverse assemblages of grasses, sedges, and forbs, often of short stature. Commonly documented species include graminoids such as Arctic rush (Juncus arcticus), narrow-panicle rush (Juncus brevicaudatus), Smith's bulrush (Schoenoplectus smithii), autumn sedge (Fimbristylis autumnalis), and tickle grass (Agrostis spp.). It is this zone that often has the specialists and rarities (e.g., Fassett's locoweed (Oxytropis campestris), alpine milk-vetch (Astragalus alpinus), long-beaked bald-rush (Rhynchospora scirpoides), rugulose grape fern (Sceptridium rugulosum), and many-headed sedge (Carex sychnocephala)). Associated forbs are silverweed (Potentilla anserina), Kalm's lobelia (Lobelia kalmii), false foxgloves (Agalinis spp.), northern St. John's-wort (Hypericum boreale), blue vervain (Verbena hastata), and water-horehounds (Lycopus spp). The high and dry upper beach zone supports denser, taller vegetation such as Canada bluejoint grass (Calamagrostis canadensis), boneset (Eupatorium perfoliatum), panicled aster (Symphyotrichum lanceolatum), flat-topped aster (Doellingeria umbellata), black bulrush (Scirpus atrovirens), and wool-grass (Scirpus cyperinus). Shrubs and seedling trees, such as white meadowsweet (Spiraea alba), speckled alder (Alnus incana), paper birch (Betula papyrifera), balsam fir (Abies balsamea), red maple (Acer rubrum), and pines (Pinus spp.) often become established on the upper beach for periods of several years, but during periods of extremely high water this zone is flooded out, succession is set back, and some of the more specialized beach plants are able to spread and thrive.
