1. Lowest node of inflorescence with whorled branches 2
Lowest node of inflorescence with 1-2 branches 10

2. Most inflorescence branches whorled 3
Only lowest inflorescence branch whorled 6

3. Spikelets uniformly distributed in inflorescence; grain globular S. australasicus (NT SA WA QLD)
Spikelets situated on apical 1/3-2/3 of inflorescence branches; grain not globular 4

4. Inflorescence branches not all whorled; ligule 0.35-1 mm long; leaves broad S. coromandelianus (NT WA QLD)
Inflorescence all, except uppermost, whorled; ligule c. 0.1 mm long; leaves narrow 5

5. Spikelets 1.1-1.5 mm long; grain quadrangular S. pulchellus (NT QLD)
Spikelets 1.6-1.8 mm long; grain lenticular S. lenticularis (NT QLD)

6. Inflorescence a very open panicle with small delicate uniformly distributed spikelets S. caroli (NSW VIC NT SA WA QLD)
Inflorescence with spikelets ±clustered on branches 7

7. Inflorescence ±open; inflorescence axis and branches distinctly scabrous
S. scabridus (QLD)
Inflorescence ±arranged in false spikes; inflorescence axis and branches smooth

8. Inflorescence branches with several false spikes ±loosely arranged S. contiguus (NSW QLD NT)
Inflorescence branches with a single false spike towards apex 9

9. Upper glume distinctly shorter than spikelet; inflorescence open S. actinocladus (NSW NT SA WA QLD)
Upper glume as long as spikelet; inflorescence mostly closed S. partimpatens (QLD)

10. Upper glume ±as long as spikelet 11
Upper glume 1/4-3/4 spikelet length 12

11. Stoloniferous; leaf sheaths usually shorter than internodes; spikelets 1.5-2mm long S. mitchellii (NSW VIC NT SA WA QLD)

S. benthamii
Rhizomatous; leaf sheaths usually
longer than internodes; spikelets ±3mm long
S. virginicus (NSW VIC TAS NT SA WA QLD)

12. Upper glume ±1/3 spikelet length 13
Upper glume 1/2 spikelet length or more 14

13. Plant coarse and tall (to 1.7m), with leaf blades to 70cm x 6-7 mm *S. pyramidalis (NSW NT QLD)
Plant shorter (to 0.75m), with leaf blades to 40cm x 2.5-3.5 mm *S. jacquemontii (NT QLD)

S. pyramidalis var. jacquemontii

14. Inflorescence a much branched and open panicle; spikelets at least 2.5 mm long S. pamelae (QLD)
Inflorescence with spikelets and branches appressed to the axis; spikelets up to 2.5 mm long 15

15. Inflorescence spicate (to semi-spicate) 16
Inflorescence spreading or spikelets arranged in spike-like clusters 18

16. Inflorescence branches bunched S. disjunctus (QLD)
Inflorescence branches not bunched 17

17. Spikelets 2.1-2.5 mm long; inflorescence branches usually appressed uniformly *S. africanus (NSW VIC TAS NT SA WA QLD)

S. capensis, S. indicus var. africanus, S. indicus var. capensis
Spikelets 1.6-2 mm long; inflorescence branches usually less appressed at base *S. fertilis (NSW VIC QLD)

S. indicus var. fertilis, S. indicus var. major

18. Lower glumes about 1/2 spikelet length; plants shortly rhizomatous
S. latzii (NT)
Lower glume less than 1/2 spikelet length; plants not rhizomatous 19

19. Spikelets spaced loosely and fairly evenly along inflorescence branches 20
Spikelets in spike-like clusters on inflorescence branches 22

20. Spikelets 1.6-2.3 mm long *S. natalensis (NSW NT QLD)
Spikelets 1.2-1.6 mm long 21

21. Inflorescence branches bearing spikelets to base S. sessilis (NSW QLD)
Inflorescence branches naked for some distance at base S. laxus (NSW QLD)

22. Inflorescence branches shorter than adjacent internodes S. creber (NSW VIC NT SA QLD)
Inflorescence branches as long as or longer than adjacent internodes 23

23. Leaf blades involute; leaf sheaths not distinctly fibrous at base of plant S. elongatus (NSW SA WA QLD)
Leaf blades flattened; leaf sheaths distinctly fibrous at base of plant S. blakei (NSW NT SA WA QLD)

Key to Sporobolus derived from Simon 1982a; Baaijens and Veldkamp
1991; Simon 1993a; Simon and Jacobs 1999

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