Water lobelia aquatic sandy pond shore (S2)
Water lobelia aquatic sandy pond shore occurs in shallow water lake and pond environments, is intermittently exposed, and subject to regular wave and ice disturbance. Most examples are characterized by a very low percent cover of aquatic, rosette-forming, stress-tolerant species (including “Isoetids”) and various floating and submersed species and submersed forms of normally emergent vegetation. Several examples occur in protected coves or interior pools on twig-rush sandy turf pond shore mats and have a much higher percent cover of vegetation, particularly of floating-leaved aquatics more sensitive to wave disturbance along exposed shores.
Characteristic Vegetation: Common species include water lobelia (Lobelia dortmanna), pipewort (Eriocaulon aquaticum), several pondweeds (Potamogeton spp.), pickerel weed (Pontederia cordata), and various reeds and rushes.
Variants: Two discernable variants are recognized, although some overlap is evident between them:
1. Pondweed - pickerel-weed variant:
This variant is characterized primarily by floating-leaved and aerenchymatous aquatics, including surface pondweed (Potamogeton epihydrus), floating pondweed (P. natans), pickerel-weed (Pontederia cordata), and lesser bur-reed (Sparganium americanum). Cover varies from very low to moderately high in coves. One of these pond shores supports New Hampshire’s only population of the globally-rare plant sclerolepis (Sclerolepis uniflora).
2. Rosette stress-tolerant Isoetid variant:
This variant has a lower frequency and abundance of floating-leaved aquatics and much higher frequency and abundance of rosette stress-tolerant species. The community is only intermittently exposed, typically as a narrow band at or near the water level line, with all or a portion of the vegetated zone staying inundated during moderately high water years. Characteristic species include pipewort (Eriocaulon aquaticum) (sparse to abundant), water lobelia (Lobelia dortmanna), Tuckerman’s quillwort (Isoetes tuckermanii) and other Isoetes, three-square rush (Scirpus pungens), humped bladderwort (Utricularia gibba), and submersed aquatic forms of grass-leaved arrowhead (Sagittaria graminea), golden-pert (Gratiola aurea), mud rush (Juncus pelocarpus), least spike-rush (Eleocharis acicularis), and lesser bur-reed.
Good examples of this community occur along the south shore of Ossipee Lake at the Ossipee Lake Natural Area in Ossipee, at White Lake State Park in Tamworth, and at Lake Massabesic in Auburn.
Water lobelia aquatic sandy pond shore often occurs as part of a larger sandy pond shore system.
Water lobelia aquatic sandy pond shore at Ossipee Lake (photo by Ben Kimball)
[note: this is a photo of the community, but it shows emergent Panicum sp., and no water lobelia.]