The slender leaves appear early in spring and are long, cylindrical and hollow, tapering to a point and about the thickness of a crowsquill. They grow from 6 to 10 inches high.

The flowering stem is usually nipped off with cultivated plants (which are grown solely for the sake of the leaves, or 'grass'), but when allowed to rise, it seldom reaches more than a few inches to at most a foot in height. It is hollow and either has no leaf or one leaf sheathing it below the middle. It supports a close globular head, or umbel, of purple flowers; the numerous flowers are densely packed together on separate, very slender little flower-stalks, shorter than the flowers themselves, which lengthen slightly as the fruit ripens, causing the heads to assume a conical instead of a round shape. The petals of the flowers are nearly half an inch long; when dry, their pale-purple colour, which has in Parts a darker flush, changes to rose-colour. The anthers (the pollen-bearing part of the flower) are of a bluish-purple colour. The seed-vessel, or capsule, is a little larger than a hemp seed and is completely concealed within the petals, which are about twice its length. The small seeds which it contains are black when ripe and similar to Onion seeds.

The flowers are in blossom in June and July, and in the most cold and moist situations will mature their seeds, though rarely allowed to do so under cultivation.