Marsilea
(named after Count A. F. Marsigli, of Bologna, 1658-1730, a patron of botany). ORD. Marsileae. This genus comprises about four species of aquatic plants, widely distributed. The two species described below are abundant in Australia. Two others are found in Europe, &c. Rhizome creeping, rooting at the nodes. Stipes often, but not always, confined at the base with those of the barren fronds, as in Ophioglosseae. Barren fronds with a long petiole or stipes, the lamina divided into four digitate leaflets, with numerous forked veins radiating from their base. Sori linear, on transverse veins proceeding from the upper side or midrib of the involucre into two series of transverse cells; each sorus consists of a few macrosporangia, each one surrounded by several microsporangia; involucres sessile or stipitate. The species thrive in turfy loam or peat, and the pots in which the plants are growing should be partially plunged in water.
M. Drummondii (Drummond's). Stipes of the barren fronds usually long and slender; leaflets broadly obovate-cuneate, or fan-shaped, more or less crenate or shortly lobed, or rarely quite entire. involucres larger than in M. hirsuta, the stipes or peduncles clustered, free from the base. Ends of the rhizome, under side of the leaflets, and involucres, more or less silky-hairy. SYN. M. macropus (H. G. F. 63).
M. hirsuta (hairy). Young ends of the rhizome densely rusty-villous. Leaflets obovate or broadly cuneate, sparingly or densely hirsute underneath, the stipes usually long and slender. involucres small, usually clustered, sessile at the base of the barren fronds, or on a stipes shorter than the involucre. M. macropus (long-stalked). A synonym of M. Drummondii.