The leaves are yellow to red at the base and have a dark and pointed tip Flowering occurs between the months of May to October.

The preferred habitat of L longitudinale is freshwater areas such as swamps, lake edges, floodways, creekbanks and seeps.

L. longitudinale occupies a hygrophilous ecological niche along with other Lepidosperma species; L.australe, L. effusum, L. gladiatum , L. quadrangulatum, L. striatum and L.

[4] It has numerous ecological associations including the Tasmanian bettong who use it as a protective habitat, the Noisy scrub-bird, Southern emu-wren and the Red-winged fairy-wren who makes nests from the leaves.

[4] The living stands of L. longitudinale in combination with leaf litter supports microbial activity that can capture excess phosphorus from run-off and incorporate the nutrient into wetland sediments.