Fennel Pondweed is a fully submerged aquatic plant and
does not have any floating or emerged leaves. Stems are profusely
branched, thread-like, rhizomatous with tuberous winter-buds. Leaves
are submerged, narrowly linear, 1-2.5 mm wide; stipular sheath adnate
to the leaf base, 2-8 cm long, tip short, pointed, or with a short
sharp point margin white, open to the base. Flowers are borne in spikes
1.5-2 cm long, cylinderic 13-17 cm long and interrupted in fruit.
Fruitlets are 3-5 mm long, 2.5-3 mm broad, obliquely obovoid, smooth.
Fennel Pondweed is a cosmopolitan weed, found all over the world.
Fennel Pondweed is used as manure, and tubers sometimes used as food.
Flowering: February-May.