Water Starwort

Starwort is so called because the young leaves float on the water surface and form a star. There are a number of different species in the family and identification is difficult because the plants are very variable - the leaf shape varies depending on the light level and water depth. For full identification the ripe fruit is required, but this is hard to find! This page is therefore compiled from various book I posess!

The plants are annuals or perennials, depending much on their environment. They can grow in deep water, shallow water or wet ground - alll of which affect their form.

The leaves vary from oval to linear and are in oposite pairs. often forming a rosette (or star) when not submerged. The flowers are tiny, green and petalless, so very easy to miss! They have separate male and femal flowers which are either solitary or paired at the bases of the leaves. Tjey flower from April to september. The fruits are 4 lobed.

The Starworts are very common in all types of temperate waters. The following species occur in Britain

Callitriche stagnalis
the lower leaves are elliptoocal-oval rather than parallel-side and linear. The floating 'Stars' are more or less circular in outline. It's smooth-stalked. The fruits have their four wings all broadly lobed.
Callitriche intermedia
Lower leaves are deeply notched and expanded with spanner-shaped tips. The fruits are 1.4mm wide with narrow wings to the lobes and the styles bent back and pressed to the sides of the fruit.
Callitriche obtusangula
The 'Star' leaves are diamond shaped and strongly veined above while the lower leaves are narrower and not translucent. The fruits are 1.5mm long with blunt, unwinged lobes. It grows in peaty or soft water.
Callitriche platycarpa
The 'Stars' leaves are rounded and weak veined above while the lower leaves are narrower and not translucent. The fruits are brownish, and narow-winged and 1.4-1.8 mm. It grows in still water.
Callitriche palustris
The 'Stars' leaves are rounded and weak veined above while the lower leaves are narrower and not translucent. The fruits are blackish, with narrow-winged lobes (at tip only) and 1.4-1.8 mm.
Callitriche truncata
The uper and lower leaves are alike, more or less parallel sided and linear. Leaves are translucent and a dark blue-green, mostly under 1cm long, with square-cut tips, scarcely notched. In still and flowing water.
Callitriche hermaphroditica
The uper and lower leaves are alike, more or less parallel sided and linear. Leaves are translucent and pale to yellow-green, mostly over 1cm long, tapering to distinctly notched tips. In still and flowing peaty water.

As an aquarium plant, the starwort requires lots of light. It does very well in a cold water aquarium, remaining beautiful and green throughout winter, despite freezing temperatures. In the tropical tank it can also be useful, but as it requires a lot of light needs to be treated as a floating plant, so it receives maximum light. It is also useful as a food plant for fish that eat vegetation. I fond my golden apple snails are very partial to it, so it gets very fragmented!


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Last modified: Sun, 19 May 2024 11:23:03 BST
Page first published 14th November 2002
Page written and © by Richard Torrens