Marsilea minuta L.

Global description
 
Marsilea minuta is a creeping aquatic fern resembling a 4-leaf clover. The leaflets are obtriangular and are arranged crosswise in a horizontal plane. They are carried by a long petiole emerging from a stem or a creeping rhizome in the vase or water. The young stems or young leaves before development form a cross typical of ferns.
 
First leaves
 
Some leaves are long-stalked, with 4 terminal leaflets, developing crosswise from a floating rhizome. Leaflets are broadly obovate to triangular with furrowed underside.
 
General habit
 
Plant with fine rhizomes, crawling into the vase or floating on water, from which develop long petioles carrying fronds with 4 terminal leaflets arranged crosswise, over the surface of the water.
 
Underground system
 
Adventitious fibrous roots at the base of each petiole.
 
Stem
 
Horizontal stem is rhizomatous, creeping or floating, thin and twisting , cylindrical, full, more or less branched, sometimes very long (several meters), with multicellular hairs at the apex.
 
Leaf
 
Frond with 4 leaflets, broadly obovate to obtriangular, 5 to 20 mm wide and long, floating, arranged in a cross on top of a petiole, 2 to 30 cm long.  The apex of the leaflets are rounded or somewhat crenate, and the base is wedged. Both sides are glabrous. The lower face is furrowed with dense linear veins.
 
Inflorescence
 
Reproductive system is made up of a lenticular sporocarp, flattened, pubescent inserted (solitary or grouped) at the base of petioles. The dehiscence of the sporocarp is made by two valves. The sporocarp encloses sporangia containing many microscopic spores.

Origin

Marsilea minutais native to the ancient tropical world (Africa, Asia, Oceania).

Worldwide distribution

Species introduced in Florida, the Caribbean Islands and at the eastern end of Brazil, Guyana.