Bur-grasses
What are they?
The bur-grasses (also known as sand-burs) are widespread in warm and temperate regions of the world, typically occurring in sandy areas, both inland and coastal. Their flowers are remarkably spiny, with the spines hardening with age and easily piercing human skin if stepped upon.
Where are they found?
These grasses are not native in the UK and only occasionally appear as seed contaminants in other products, such as imported wool, grain or birdseed mixes. Thus, they typically turn up on disturbed ground or in urban environments.
Identification
Click here for help with some of the terminology used on the grass pages. Only a single species has been recorded in our region and is included here. However, there are a number of very similar bur-grass species, so it would be wise to confirm any find with sources covering other species.
Small Bur-grass Cenchrus longispinus
Introduced annual from North America, recorded once near Cambridge. Flowers August to September. Plants 10-80cm in height and typically forming small clumps or single shoots. Leaf blades 3-7mm wide, flat, rough and sometimes with a few scattered hairs. Leaf sheaths smooth except for a hairs around the margin. Ligules a ring of hairs, 0.7-1.7mm long. Flower spike up to 10cm long consisting of a series of bur-like clusters along a central stem. Spikelets in clusters of two or three, 6-8mm long, each with two florets, the lower sterile and almost absent, the upper bisexual. Each cluster of spikelets is surrounded by a cluster of spines with backward-pointing barbs on them.
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