1	"Lemma margins with cilia 0.5 mm long or more"	2
1	"Lemma margins glabrous, but often scabrous, the outgrowths never to 0.5 mm"	3
2	"Lemma margins ciliate from base to awn"	"Vulpia ciliata"
2	"Lemma margins glabrous in lower half"	"Vulpia myuros"
3	"Lemma with a pointed callus, more than 0.5 mm long; overall length of lemma (including awn) more than 25 mm; lower glume c. 1 (rarely to 2) mm long, less than one-tenth as long as long-awned upper glume"	"Vulpia fasciculata"
3	"Lemma with a rounded callus, less than 0.4 mm long; overall length of lemma mostly less than 25 mm; lower glume more than one-tenth as long as unawned or shortly awned upper glume"	4
4	"Lower glume 2.5–5 mm long, from one-half to three-quarters as long as upper glume"	"Vulpia bromoides"
4	"Lower glume 0.5–3 mm long, usually less than one-half as long as upper glume"	5
5	"Panicle usually fully exserted from uppermost leaf-sheath; lower glume from one-quarter to one-half as long as upper glume"	"Vulpia muralis"
5	"Panicle usually not fully exserted from uppermost leaf-sheath; lower glume from one-tenth to four-tenths (but mostly less than one-quarter) as long as upper glume"	"Vulpia myuros"