A tall, relatively hairless perennial grass with broad, long leaves with a prominent midrib underneath, jagged membranous ligule and erect stout stems arising from a creeping, rooting, scaly rhizome. It produces a purplish-brown pyramidal, seed head about 25 cm long in summer. It is listed as one of the 10 worst weeds in the world
As A Soil Indicator:
Very low Calcium, Very high phosphate, Very high Magnesium, High Manganese, High Iron, Very high Sulphur, High Copper, High Zinc, Very high Boron, High Chlorine, High Selenium, Aluminum, High Salt, Very little organic matter, Anaerobic bacteria, Prefers damp soils.
Perennial. Flowers November to June. Seeds germinate in spring to early summer. Initially top growth is slow as roots and rhizome develops. Flowering commences about 7 weeks after germination. After flowering the rhizome grows quickly. Flowering is continuous over the summer with a peak in early and late summer. Rhizomes dormant over winter. Top growth dies after frosts in winter. New shoots emerge from rhizomes in spring. Shoots from rhizomes emerge earlier and grow faster than those from seed. Rhizomes are short-lived and are produced in one season, sprout in the next season to form a new plant then die as new rhizomes are formed.
Aggressive weed, Crosses with sorghum producing weedy biotypes.
Toxic when stressed, frosted, wilted or stunted. Cattle, sheep and pigs have been poisoned in Australia. Cattle appear to suffer the worst losses. It may also contain toxic levels of nitrate and cause nitrate poisoning especially during periods of vigorous growth