1. Lemma with prominent awn 2
Lemma awnless, mucronate or shortly awned 29

2. Awn at least twice spikelet length 3
Awn shorter than, as long as or slightly longer than spikelet length 17

3. Palea awns separate, almost as long as lemma awns E. triseta (NT WA QLD)
Palea awns absent or fused for some distance of their length and much shorter than lemma awns 4

4. Inflorescence ±loose 5
Inflorescence dense 12

5. Palea without awns 6
Palea with awns, fused somewhere along
their length

6. Spikelets (without awns) less than 5 mm long 7
Spikelets 7-8 mm long 8

7. Spikelets c. 2 mm long E. minuta (NT)
Spikelets 3-4 mm long E. agrostidea (NT QLD)

8. Inflorescence less than 5cm long E. pauciflora (NT WA)
Inflorescence more than 5cm long 9

9. Annual; leaf blades with vesicles on upper surface E. basalis (NT QLD)
Perennial; leaf blades scabrous or glabrous on upper surface E. burkittii (NT WA QLD)
E. burkittii var. hirsutissima, E. laidlawii

10. Leaf-blades vesicular on upper surface E. vesiculosa (NT QLD)
Leaf-blades not vesicular on upper surface 11

11. Palea awns fused along most of their length E. rara (NSW NT WA QLD)
Palea awns fused only at base E. stipacea (NT QLD)

12. Annual; palea awns fused only at base E. armitii (NT WA QLD)
Perennial; palea awns fused for most of their length 13

13. Glumes more than 8 mm long 14
Glumes 4-5 mm long 16

14. Lemma obtuse without lateral grooves apically; culm internodes hairy to some degree E. squarrosa (QLD)
Lemma acute, with lateral grooves apically; culm internodes glabrous 15

15. Lemma hairy all over; palea c. 9 mm long E. schultziana (NT)
Lemma hairy in lower half; palea c. 7 mm long E. sulcata (NT WA)

16. Nodes glabrous E. glauca var. glauca (NT WA QLD)
Nodes bearded E. glauca var. barbinodis (NT WA QLD)

17. Spikelets (without awns) longer than 6 mm 18
Spikelets (without awns) to 5 mm long 21

18. Annual E. aristidea (NSW NT SA WA QLD)
E. aristidea var. minor
Perennial 19

19. Awns strongly recurved in mature spikelets E. festucacea (NT WA QLD)
Awns straight in mature spikelets 20

20. Lemma pilose on margins; awn shorter than lemma; leaf-blades filiform E. avenacea (NT WA)
E. setacea
Lemma pilose all over back; awn as long as lemma; leaf-blades flat to involute E. triodioides (NT WA QLD)

21. Perennial 22
Annual 24

22. Lemma with a groove in the upper glabrous
part near both margins
E. imbricata (WA)
Lemma without grooves 23

23. Spikelets normally 1-flowered E. pallescens var. gracilis (QLD)
E. anomala
Spikelets normally 2-flowered E. pallescens var. pallescens (QLD)
E. muelleri, E. yarrabensis

24. Inflorescence very open; leaf-blades usually flat; spikelets (excluding awns) up to 3.5 mm long 25
Inflorescence contracted to some degree; leaf-blades usually involute; spikelets 3.5 mm or more long 27

25. Spikelets c. 2.5 mm long; awns shorter than lemma E. sp. C  (Dugald River, Simon 3007) (NT WA QLD)
Spikelets 3-3.5 mm long; awns as long as lemma 26

26. Glumes acuminate, longer than wide; florets
slightly shorter than glumes; lemma ciliate on margins for their entire length; hairs on culms and foliage chiefly antrorse
E. ciliata (NT WA QLD)
Glumes obtuse, almost as wide as long; florets equal to glumes or slightly longer; lemma glabrous on margins near apex; hairs on culms and foliage chiefly retrorse E. semiciliata (NT WA)

27. Inflorescence in tight clusters E. compacta (NT)
Inflorescence loosely contracted 28

28. Lemma (excluding awn) 2-3 mm long, with awn longer than lemma E. filiformis (NT QLD)
Lemma 3.25-4 mm long, with awn shorter than lemma E. humilis (NT QLD)

29. Spikelets to 2 mm long E. capillaris (NT)
Spikelets more than 2 mm long 30

30. Lemma more than 10 mm long E. nervosa (WA NT QLD)
Lemma less than 10 mm long 31

31. Annual 32
Perennial 37

32. Inflorescence a spicate panicle 33
Inflorescence an open panicle 35

33. Lemma not ciliate on margins E. fastigiata (WA NT)
Lemma ciliate on margins 34

34. Inflorescence densely spicate, up to 3.5 cm
long when mature
E. pulchella subsp. pulchella (NSW NT SA WA QLD)
E. insigniana
Inflorescence loosely spicate, more than 3.5 cm long when mature E. pulchella subsp. dominii (NT WA QLD)

35. Spikelets less than 3.5 mm long E. axillaris (NT)
Spikelets more than 3.5 mm long 36

36. Spikelets c. 7 mm long E. melicacea (NT WA QLD)
Spikelets c. 5 mm long E. nodosa (NT WA)

37. Inflorescence reduced to 1-2 spikelets; culm internodes woolly and completely covered by leaf sheaths E. scleranthoides (NT WA QLD)
Inflorescence of few to numerous spikelets; culm internodes not as above 38

38. Butt distinctly thickened and very woolly 39
Butt, if thickened and/or woolly, only slightly so 40

39. Inflorescence open E. helmsii (NSW NT SA WA QLD)
Inflorescence densely spicate E. basedowii (NT)

40. Lemma 7-9 mm long 41
Lemma less than 7 mm long 47

41. Lemmas distinctly longer than glumes 42
Lemmas subequal or slightly longer than

42. Lemmas glabrous E. tenuiculmis (WA)
E. pallida
Lemmas pilose 43

43. Glumes 9-11-nerved; lemmas grooved; panicle
branches not capillary
E. benthamii (NT SA WA QLD)
Glumes 7-nerved; lemmas not grooved; panicle branches capillary E. bleeseri (NT)

44. Inflorescence ±loose E. gardneri (WA)
Inflorescence congested 45

45. Inflorescence with swollen yellowish glands on rachis E. glandulosa (NT WA)
Inflorescence without glands 46

46. Panicle usually ovate and dense E. ovata (SA WA)
E. ovata var. villosa
Panicle often irregular E. flaccida (NT WA)

47. Lemma with an acute apex 48
Lemma with a mucronate apex 50

48. Lemmas glabrous E. glabrata (NSW QLD)
Lemmas hairy 49

49. Glumes 3/4 spikelet length; panicle
E. lanata (WA)
Glumes ±as long as spikelet; panicle
E. obtusa (NT WA QLD)
E. obtusa var. major, E. major

50. Spikelets c. 3 mm long; panicle open E. insularis (QLD)
Spikelets 5-6 mm long; panicle ±congested 52

52. Culms 4-6 noded; leaf-blades to 4cm
E. mucronata typical form (NSW NT SA WA QLD)
Culms more than 6 noded; leaf-blades less
than 1.5 cm long
E. mucronata desert form (NT QLD)

Key to Eriachne derived from Bentham 1878; Lazarides 1995; Lazarides et al 2005

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