Description
Felwort is a glabrous annual with usually unbranched stems that are 5-15 cm high. The opposite leaves are narrowly oblong to lance-shaped and 1-3 cm long. White or bluish flowers are borne on slender, 1-3 cm long stalks which arise from the axils of the upper leaves. The 5 spreading, lance-shaped petals are 6-15 mm long and are united at the base and subtended by slightly longer, narrow, green sepals. Each petal has 2 small appendages at the base, and there are 5 stamens. The fruit is a many-seeded, egg-shaped capsule that is as long as the petals.
Diagnostic Characteristics
SWERTIA PERENNIS has similar flowers but is a perennial. Annual gentians have tubular rather than star-shaped corollas. This plant is often overlooked because it blooms in August.
Habitat
The more salient features of the habitat of LOMATOGONIUM ROTATUM include moist soils, full sunlight, minimal competition, and, in eastern North America, close proximity to the sea along outer islands and headlands. Hence it most characteristically grows in thin soils bordering headlands or ledges or in pockets of sandy or gravelly soil. A soil test from Red Head on Great Wass Island, performed by the Maine Soil Testing Lab, indicates circumneutral pH and an excessive level of calcium. It is frequently found in seepage areas between boulders and in turf surrounding temporary and permanent brackish and freshwater pools, and in moist rock crevices. It generally does not colonize crevices close to the breaking surf.
Associated species of LOMATOGONIUM ROTATUM in Maine include: AGROSTIS STOLONIFERA, ASTER NOVI-BELGII, A. NEMORALIS, CAMPANULA ROTUNDIFOLIA, CAREX CANESCENS, C. VIRIDULA, DESCHAMPSIA FLEXUOSA, EMPETRUM NIGRUM, EUPHRASIA CANADENSIS, E. RANDII, FESTUCA RUBRA, IRIS HOOKERI, JUNCUS FILIFORMIS, PLANTAGO JUNCOIDES VAR. DECIPIENS, PRENANTHES TRIFOLIATA, PRIMULA LAURENTIANA, SAGINA NODOSA SSP. BOREALIS, SOLIDAGO BICOLOR, TRIGLOCHIN MARITIMA, and VIOLA SEPTENTRIONALIS.
Ecology
Lomatogonium rotatum's distribution in Maine is restricted to the moist maritime zone along the coast of eastern Maine (Famous and Campbell 1984). Compared to inland and coastal sections farther west summer temperatures are cooler, the incidence of fog is higher, rainfall and fog-drip rates are higher, and evaporation rates are lower, providing an abundance of water. These conditions are not as extreme when Lomatogonium rotatum is in full bloom in August and September.
Reproduction
Little is known about the reproductive biology of this species. Floristic manuals indicate that this is an annual or biennial. Longer term studies are needed to determine its duration. The pollinators are unknown. Syrphid flies, bumblebees, and several species of butterflies are present in or near their populations, and a syrphid fly was seen visiting LOMATOGONIUM in late September on Water Island (Inner Water Island). It is likely that nectar is the reward for pollinators, although we did not verify the presence of nectar. It appears that this species is reproducing succesfully by seed. Many reproductively mature plants were observed as well as reproductively immature, non-flowering individuals. It is also unknown how the seeds are dispersed. Because of its short stature migratory songbirds, esp. Fringillids, may be involved with seed dispersal and/or seed predation.