Northern Prairie Wildlife Research Center
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.
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