Cyperaceae
Leaf sheath closed or rarely open and then the perianth reduced to bristles or minute scales Cyperaceae
Flowers bisexual or unisexual but never enclosed in a utricle and never apparently separated into unisexual spikelets
Spikelets with 1–2 perfect flowers, other flowers male or sterile
Perianth scales or bristles absent
Glumes spirally imbricate (Fig. 46 a,m)
Ultimate branches straight, erect or pendulous. Culms often more than 1 m high. Spikelets in pairs, 12–16 mm long. Widespread. Sandy soils. Heath and DSF Caustis pentandra
Ultimate branches flexuose, curved into spirals. Culms up to 60 cm high