Pampas grass (Cortaderia selloana )

Cortaderia_selloana

Pink pampas grass (Cortaderia jubata )

Cortaderia jubata

Family: Poaceae

Status: Both species are declared noxious in category W2 (must be continuously suppressed and destroyed) in all south coast Local Government Areas.

Description:
A very large tussock grass with large white or beige (C. selloana) or pink to mauve (C. jubata) feathery plume-like seed heads on long stems to 3m high. Leaves have serrated edges.

Preferred habitat and impacts:
A garden escapee usually found close to towns. It has shown the ability to spread quite extensively especially in disturbed open situations and in moist soils. It tolerates saline conditions. It can form dense stands, choking out all other vegetation. Could create a fire hazard.
Pampas grass used to be a fairly benign garden plant in Australia, but the importation of new strains in the 1970’s has made it a more aggressive weed.

Dispersal:
Seed is blown very long distances on the wind, and also spread in water, and by machinery in soil. Underground stems may be spread by machinery. Plumes are often cut for dried flower arrangements, with the result that seed will be spread when they are discarded.

Look-alikes:
The native common reed (Phragmites australis) also has seed in plumes, but these are carried at the tip of bamboo-like leafy stems. It occurs in swamps and along creeks. Saw-sedges (Gahnia species) have similar very robust tussocks, but they have more open branched seed heads and shiny red or black seeds.
The introduced garden plant, giant reed (Arundo donax) also has a large plume-like seed head, but it, like common reed, is carried on a bamboo-like leafy stem. It also sometimes escapes from cultivation in moist situations.

Phragmites australis Gahnia sieberiana

Control
If plants are carrying seed, remove the seed heads very carefully and bag for burning or deep burial before attempting any other control. Small plants can be dug out, taking care to remove all the roots. A backhoe may be required for large plants, if they are in sites where this would not cause damage to native vegetation. If spraying, it will be more effective to remove old foliage by slashing or burning, then spray regrowth. Stock find young plants palatable, so infestations are unlikely to develop in grazed sites.