Sedges are differentiated from grasses by a number of characteristics, but the simplest one is the stem. A sedge stem is triangular and solid; a grass stem is round and hollow. There are some sedges that are annuals but all the of the Carex species are perennial.

What sedges look like?

Sedges usually have triangular stems with leaves arranged in groups of three and are similar to grasses in many attributes. Sedge species may be found in a wide range of conditions, ranging from very wet to dry and in many soil types. ... Flowers are extremely small and numerous and arranged in spikelets atop the stem.

How can you tell grasses and sedges?

'Sedges have edges, rushes are round, grasses have knees that bend to the ground. ' The 'knees' of grasses are joint-like nodes found along round, hollow stems. The stems of sedges and rushes are solid; in cross-section the stems of rushes are round, while those of sedges are triangular and so have edges.