Aquatic and Wetland Vascular Plants of the Northern Great Plains

5. Marsileaceae, the Pepperwort Family

1. Marsilea L. -- Pepperwort, water clover

1. Marsilea vestita Hook. & Grev.

Creeping perennial (or acting as an annual when the habitat dries) in mud or shallow water. Stem a superficial, sprawling rhizome, rooting at the nodes. Leaves 4-foliate, with 4 wedge-shaped leaflets, giving the appearance of a 4-leaved clover, often floating, the leaflets obdeltate, 2-15 mm long and about as wide; petioles slender, lax when submersed, 2-20(30) cm long, greatly lengthened to accommodate the blade when submersed. Sporangia heterosporous, enclosed in solitary oval sporocarps borne near the base at the nodes; sporocarps brown, 4-7 mm long, strigose; sori in 2 rows inside the sporocarp, with apical megasporangia and lateral microsporangia; spores tetrahedral, the microspores numerous, the megaspores solitary in the sporangia; gametophyte aquatic, nonphotosynthetic. Jul--Sep. Mud or shallow water of temporary ponds, streams or ditches; occasional; (MN to B.C., s to AR, TX, Mex. and CA; intro. in FL). M. mucronata A. Br.

Pilularia americana R. Br., American pillwort, is another member of the Marsileaceae that has been found in Cherry Co., NE. It is an inconspicuous, low, mat-forming plant with tufts of filiform leaves 2-11 cm long arising from creeping, filiform rhizomes. The sporocarps, which are borne on short stalks from the rhizomes, are smaller (2-3 mm in diameter) and more round than those of Marsilea vestita. American pillwort occurs in shallow water or on exposed substrates of lakes and temporary pools in sandhill regions mainly south of this region.

Reference:

Stason, M.  1926.  The marsileas of the western United States.  Bull.
     Torrey Bot. Club 53:473-478.


Marislea vestita. When stranded by receding water, the 4-lobed leaves are borne on erect petioles and the plant produces the bean-shaped sporocarps near the petiole bases as shown in the drawing.

Return to Family -- Marsileaceae - The Pepperwort Family