Grass stems are generally hollow and cylindrical with swollen nodes. They have alternate leaves in two ranks and small inconspicuous flowers. The fruits are grains.
There are over 10,000 grass species in the world. Many grasses are important human crop species (e.g. wheat and rice); they also feed many grazing animals.
The ancient woodland indicator wood melick, Melica uniflora, is a bright green grass that grows in dense patches. It has thin stems and loose, nodding heads of dark purple flowers. Tall wood millet, Milium effusum, is also an indicator of ancient woodland. Its flowers grow in loose whorls out from the stem.
The solid or pith-filled stems of sedges tend to have defined edges to their often triangular shape, and leaves in three ranks. The flowers are in spikes and the fruit is a single-seeded nut.
Pendulous sedge, Carex pendula, is a striking plant that favours wet, ancient woodland and riversides. It forms large tufts and its long, distinctive flower spikes hang loosely. It can be an ancient woodland indicator, but it is also a favourite of gardeners so may have been actively planted or escaped domestication. Wood-sedge, Carex sylvatica, is densely tufted and is another ancient woodland indicator.
Rushes have solid or pith-filled stems that are generally round or rounded. Their flowers grow in clusters at the end of the stem, sometimes with a bract that grows up and looks just like a continuation of the actual stem. The fruit is a many seeded capsule.