Clover fern (Marsilea vestita) is another aquatic fern that does not resemble our visual idea of a fern. This member of the Marsilea Family (Marsileaceae) inhabits seasonally wet habitats such as vernal pools, pond margins, creek beds and muddy places from sea level to about 7,000 feet. Clover fern is also tolerant of alkaline conditions. It is found generally west of the Mississippi with colonies in Gulf States.
Clover fern has slender leaf stalks that grow from creeping underground stems. The light green through yellow, red and brown leaves may form in clusters or spread out along the creeping stem. Each palmately compound leaf has 4 hairy, slightly hairy or smooth leaflets and resembles a four leaf clover.
Sexual reproduction occurs through spores that are produced in solitary, oval, dark brown, hard-sided capsules borne on short stems nestled among the leaf stalks. The spore capsule contains both male and female spores. When the spores are ripe the capsule splits open allowing the entry of water. As the spores leave the capsule the female spores are fertilized. Spore capsules can remain viable for 100 years in soil. Asexual reproduction is by runners.
Clover fern spore capsules are eaten by waterfowl and fish find shelter amid clover fern leaves.
Waterclover and hairy pepperwort are other common names for M vestita.
These clover fern plants were found in a pond along the Quarry Trail in Ash Creek Wildlife Area (Modoc County CA) and were photographed in May and July.