What Does It Look Like?
What is it?
Spiny Burrgrass (Cenchrus spinifex) [as Cenchrus incertus] is an upright tufted or spreading annual, or occasionally biennial or perennial grass, that regrows from a crown. It usually growing to about 60 cm tall, but sometimes reaching up to 80 cm in height, sometimes with pink0reddish colour at the base of the stem. The narrow leaf blades are 2, 5 cm sometime to 20 cm long and 2–8 mm wide, flat-folded or in-rolled, and are mostly smooth and hairless. Leaf sheaths (part of the leaf rolled around the stem) are hairless or sparsely hairy. A ligule (a small appendage on the top of the leaf sheath where sheath meets the leaf blade) is a fringe of tiny hairs 1–2 mm long.
The flower (seed-head) is spike-like in appearance and is often partially enclosed within the uppermost leaf sheath and and composed of 10–40 spiny 'burr-like' structures 2–5 mm long, mostly densely packed on stem, but sometime interrupted with stem between burrs. the spiny burrs are hairless, with spines all flat, the longest to 4 mm long. Burrs contain a cluster of two to four flower spikelets and each flower spikelet usually produces a single seed. Burrs are reddish or purplish-green colour when young but turn straw-coloured or brown as they mature. Flowering occurs mostly during summer and autumn.
The fruits are 'burrs' which are 3–10 mm across, each with usually 10–40 sharp spines that are 3.5–5.5 mm long and have relatively broad bases. These 'burrs' are almost stalkless or borne on very short stalks 0.5–2 mm long, and when ripe they usually detach from the flowering stem entirely. The smooth seeds are 2–4 mm long by 2–3 mm wide and are egg-shaped, but flattened on one side, and remain well hidden within the burrs (Navie 2004).
For further information and assistance with identification of Spiny Burrgrass, contact the herbarium in your state or territory.
Red, Purple, Green, White, Brown
Growth form (weed type/habit)
Where it currently grows? Preferred habitat
Spiny Burrgrass is found mostly in sub-tropical, semi-arid and warmer temperate climates. This species is a weed of disturbed sites, waste areas, roadsides, pastures and cultivation. It prefers sandy soils (Navie 2004).
Are there similar species?
Spiny Burrgrass is very similar to another species also known as Spiny Burrgrass (Cenchrus longispinus), Mossman River Grass (Cenchrus echinatus) and Buffel Grass (Cenchrus ciliaris).
The burrs on Spiny Burrgrass (Cenchrus longispinus) while also having several rows of larger flattened spines, usually with 40–70 spines in total. The burrs on Mossman River grass (Cenchrus echinatus) do not have stalks and only have one row of larger flattened spines.
Buffel Grass (Cenchrus ciliaris) has seed-heads that do not produce spiny 'burrs'. Instead, its seed-heads bear flower spikelet clusters that have numerous long stiff bristles (Navie 2004).