Lake Quillwort

Isoetes lacustrisThis is a small aquatic plant that occurs as a tuft of straight dark green linear and subulate leaves shooting off a short rootstalk. At the bases of the outer and middle leaves, there are oval spore-forming sacks with whitish rippled spores.

An extremely rare species, it displays a narrow ecological amplitude and acute sensitivity to the cleanliness of water.

It grows on sand and sandy ooze of oligotrophic water at the depth of 4-5 m, often in colonies.

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