1	"Fertile spikelet subtended by 6-7 sterile spikelets"	"Phalaris paradoxa"
1	"Fertile spikelet not subtended by sterile spikelets"	2
2	"Glumes wingless on keel or with narrow wings"	"Phalaris arundinacea"
2	"Glumes prominently winged on keel"	3
3	"Sterile lemmas subequal"	4
3	"Sterile lemmas unequal; lower very small or both absent"	5
4	"Sterile lemmas more than 2 mm long"	"Phalaris canariensis"
4	"Sterile lemmas 1 mm long or less"	"Phalaris angusta"
5	"Glumes drawn to a point at apex"	"Phalaris minor"
5	"Glumes not drawn to a point at apex"	"Phalaris aquatica"