Pilularia

Scientific name

Pilularia L.

Common names

pillwort, pepperweed

Family

Marsileaceae

Similar genera

Eleocharis, Isolepis, Lilaeopsis, Limosella, Littorella

Native distribution

North America, South America, Europe, Pacific Islands in New Zealand, Australia

Species cultivated

Pilularia globulifera L. [synonym of Calamistrum globuliferum (L.) Kuntze.]

Adventive distribution

may be naturalized in environments within their native distribution

Weed status

not weedy

Habit

submerged, emergentemergent:
(adj) (syn. emersed) with parts raised out of the water; extending up out of the water
or seasonally inundated fern forming dense clones

Brief description

Small creeping fern, resembling a grass or sedge. Rhizomes long-creeping, slender, rooting at nodes. Leaves filiformfiliform:
(adj) thread-like; long and thin
, tereteterete:
(adj) +/- circular in cross section
, lacking expanded blades, glabrousglabrous:
(adj) without hairs or scales
to sparsely pubescentpubescent:
(adj) (1) covered with short, soft hairs; (2) bearing hairs
. Sporocarps borne on short stalks at the base of leaves; globoseglobose:
(adj) spherical or nearly so
, densely to sparsely hairy, less so at maturity; dehiscing into 4 valves; may be absent in permanently submergedsubmerged:
(adj) (syn. submersed) under water; submerged below the water surface
plants.

Natural habitat

in shallow water of ponds, vernal pools and marshes, on lake margins with fluctuating water levels; submergedsubmerged:
(adj) (syn. submersed) under water; submerged below the water surface
in water up to 1 m deep

Additional comments

This genus is in need of revision and the status of the various species is unclear, with estimates ranging from one species to six. Several of the previously accepted species are currently unresolved and these species are still recognized. Calamistrum globuliferum (L.) Kuntze., the sole species within Calamistrum, was previously placed in Pilularia.