1. Base of joint and pedicel producing a distinct pore 2
Base of joint and pedicel without a pore 4

2. Leaf blades narrow; inhabits rocky cliffs I. sp. (George Creek I.D.Cowie+ 5306) (NT)
Leaf blades broad; inhabits swamps 3

3. Inflorescence of many digitate racemes I. polystachyum (QLD)
Inflorescence of 2-3 racemes I. tropicum (NT QLD)

4. Lower glume of sessile spikelet transversely rugose 5
Lower glume of sessile spikelet not transversely rugose 6

5. Pedicelled spikelet developed I. rugosum var. rugosum (NT QLD)
Pedicelled spikelet much reduced I. rugosum var. segetum (NT QLD)

6. Decumbent or stoloniferous habit 7
Erect habit 9

7. Annual with mature inflorescence to 2 cm long and leaf blades to 5 mm wide I. decumbens (NT QLD)
Perennials with mature inflorescence more than 2 cm long and leaf blades more than 6 mm wide 8

8. Stoloniferous I. muticum (QLD)
Decumbent, without stolons I. triticeum (NSW QLD)

9. Raceme single 10
Racemes paired 11

10. Sessile spikelet c. 10mm long, with silky hair I. albovillosum (WA)
Sessile spikelet 6-7mm long, glabrous I. fragile (QLD)
I. baileyi, Digastrium fragile

11. Lower glume with transverse undulations I. barbatum (NT)
Lower glume smooth 12

12. Nodes glabrous I. australe var. arundinaceum (NT WA QLD)
I. arundinaceum
Nodes hairy 13

13. Leaves, rachis internodes and pedicels hairy I. australe var. villosum (NT QLD)
I. villosum
Leaves, rachis internodes and pedicels glabrous I. australe var. australe (NSW NT WA QLD)

Key to Ischaemum derived from Bentham 1878; Simon 1989b

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith