Description: Aquatic or semi-aquatic delicate glabrous herbs, mostly monoecious.
Leaves opposite, usually entire, often clustered towards the end of branches.
Flowers unisexual, axillary, naked, paired or solitary, when paired usually one of each sex, subtended by 2 bracteoles or these absent or caducous. Male flower consisting of a single stamen. Female flowers with 2 carpels, but becoming 4-locular by septation.
Fruit c. 1–2 mm long, flattened, breaking into 4 1-seeded mericarps.
Distribution and occurrence: World: c. 75 species, cosmopolitan. Australia: 9 species (6 species native), all States except N.T.
Text by S. W. L. Jacobs
Taxon concept:
Taxa not yet included in identification key
Callitriche brutia
| | Key to the species | |
| 1 | Fruit broader than long | 2 |
| Fruit almost circular or longer than broad | 3 |
| 2 | Mature leaves rhombic, sometimes with lateral teeth; mericarp wing 25% or more the breadth of the mericarp | Callitriche muelleri |
| Mature leaves linear to linear-obovate, never with lateral teeth; mericarp wing less than 20% the breadth of the mericarp
Back to 1 | Callitriche sonderi |
| 3 | First-formed leaves linear, 1-veined; portion of mericarp closest to point of attachment of fruit swollen | Callitriche umbonata |
| First-formed leaves linear-spathulate to spathulate, 3- veined; lower part of fruit broader than top but no part of mericarp particularly swollen
Back to 1 | Callitriche stagnalis |
|
