Frog’s bit

Floating Leaf Plants

Limnobium spongia:

Frog’s bit

Limnobium spongia (Bosc.) Steud.: Frog's bit. Hydrocharitaceae (frog's bit family). 

Native perennial. The plant is made up of a rosette of leaves that usually floats freely; older plants can root in mud to form dense mats. Roots lined with hairs emerge at the base of the rosette; daughter plants are produced on slender stolons. In unrooted pre-flowering plants, the rosette of young heart-shaped leaves lies flat on the water surface. Leaf blades are 0.8 - 2 in (2 - 5 cm) long, with slender, flexible leaf stalks. A distinct inflated area of purplish spongy cells on the underside of the leaf blade adds buoyancy; networks of cross veins can be seen between the main veins. At maturity and flowering, leaf stalks are spongy and thicker (but not bulbous), up to 6 in (15 cm) long, with two ridges down their length. The rounded oval leaves are held above the water to 1 ft (30 cm). While these older leaves are thicker and less heart-shaped, cross veination remains. The white flowers are clusters of thread-like petals, held on short stalks at the base of the plant; as the spherical, green-striped berries mature these stalks curve downwards.