Form: Bolboschoenus caldwellii is a perennial sedge between 30-90cm tall
Foliage: The leaves are arranged alternately along the stem. They have long, closed, leathery sheaths with spreading blades up to about 35cm long and 5mm wide tapering into a point
Flowers: The seed heads are compact heads of 2-6 spikelets (units) near the stem tip, chestnut brown in colour
Fruit: Nut lenticular with concave faces, broad-obovoid, 3.5-4mm long, 2.5-3mm diameter, straw-coloured to dark golden brown, shining
Habitat: Occasional, in swamps or inland along artesian bore drains
Distinctive Features: More slender than the other species, usually with leaves erect, with a small clustered inflorescence, and the nut broad and always lenticular, with surface minutely but obviously reticulate under a hand lens
Similar species: Shorter stems than Bolboschoenus medianus and Bolboschoenus fluviatis
Comments: Tolerates brackish conditions, useful for upper reaches of estuarine water bodies
