1. Fertile spikelet subtended by 6-7 sterile spikelets *P. paradoxa (NSW VIC TAS SA WA QLD)
Fertile spikelet not subtended by sterile spikelets 2

2. Glumes wingless on keel or with narrow wings 3
Glumes prominently winged on keel 4

3. Leaves uniformly green *P. arundinacea var. arundinacea
Leaves longitudinally striped with white stripes *P. arundinacea var. picta (NSW SA WA)

4. Sterile lemmas subequal 5
Sterile lemmas unequal; lower very small or
both absent

5. Sterile lemmas more than 2 mm long *P. canariensis (NSW VIC TAS SA WA QLD)
Sterile lemmas 1 mm long or less *P. angusta (NSW WA QLD)

6. Sterile lemmas absent or reduced to two tiny scales; fertile floret glabrous *P. coerulescens (NSW VIC WA)
Sterile lemmas unequal or lower reduced to a scale; fertile floret pubescent 7

7. Glumes drawn to a point at apex *P. minor (NSW VIC TAS SA WA QLD)
Glumes not drawn to a point at apex *P. aquatica (NSW VIC TAS SA WA QLD)
P. tuberosa, P. tuberosa var. stenpotera

Key to Phalaris derived from Anderson 1961; Vickery 1975

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