Family: Juncaceae

Status:

Description:
Sharp rush is a robust tussock plant to about 1.5m high (though usually more like 1m) and about the same spread. The flowering stems and leaves look exactly the same, except that the leaves are a little shorter and lack the tuft of flowers or fruits attached to one side near the top. They are round in cross-section, 2-4mm in diameter, blue-green in colour and have a sharply pointed tip. This tip is actually painful to touch with the hand (try patting the top of the tussock with your palm).

Preferred habitat and impacts:
Sharp rush grows in wet soil, in areas which are occasionally but not permanently under water. It will grow in both freshwater and saline situations.

Dispersal:
Spread by seed in water or contaminated soil, in mud on vehicles, machinery and boats. The clumps also spread gradually by underground rhizomes.

Look-alikes:
There are many native and a few introduced rushes (Juncus species) which all look very similar. Sea rush (Juncus kraussii ) is one of the most similar, growing in saline and brackish situations. However, with a bit of experience sharp rush can be distinguished by the very pointed nature of its tips. Most other rushes are not actually painful to bounce the hand off, although they are all sharp. It is also more robust (bigger tussocks, wider individual stems) than most of the native rushes found on the south coast. Its stems are very hard. It is impossible to squash them by squeezing with the finger and thumb. This contrasts with many of the native rushes in which it is easy, or at least possible, to squash the stems. Its flower and seed heads also tend to be bigger and more red-brown in colour. It often grows side by side with native species, and these differences are then quite obvious. An isolated plant can be trickier. The definitive distinguishing feature is the fact that the seed capsule (nut) protrudes well beyond the "tepals" which surround it. The tepals are equivalent to the sepals and petals of more conventional flowers, and are retained around the seed capsule. Another introduced rush Juncus imbricatus also has this feature, but most native rushes have the nut about the same length as the tepals, or slightly shorter or longer. A magnifying glass may be needed to see this feature.

Control
Small or isolated plants can be dug up (taking care during disposal not to spread the seed) but the amount of work involved would be prohibitive for large infestations. For these herbicide may be necessary, but a permit will be required from the Environmental Protection Agency to apply any herbicide to a water body. Only a limited number of herbicides are registered for use over water. If you suspect you have sharp rush present notify your local weed control authority (usually Council) and take their advice on control methods.