1	"Micronemata present (younger or poorly developed stems may lack the micronemata but the initials will still be present and visible in a stem whole-mount)"	2
1	"Rhizoids restricted to base of plant and around buds"	4
2	"Leaves and plant small with leaves seldom exceeding 4 mm long; costa short, ending at about 3/4; leaf border unistratose"	"Rhizomnium gracile"
2	"Leaves and plant larger; costa percurrent or ending within a few cells of apex; leaf border one or more cells thick"	3
3	"Costa confluent with the limbidium or ending within 2-3 cells of the limbidium; dioicous; leaves on at least the well developed stems more than 7 mm long"	"Rhizomnium magnifolium"
3	"Costa ending several cells below the limbidium; synoicous; leaves smaller"	"Rhizomnium pseudopunctatum"
4	"Limbidium obvious and extending to the apex; costa mostly confluent with the limbidium and apiculate"	5
4	"Limbidium narrow near base and seldom extending to apex; costa of most leaves subpercurrent with apex hardly apiculate"	6
5	"Laminal cells mostly about 2:1 with walls evenly thickened; stems reddish"	"Rhizomnium punctatum"
5	"Laminal cells mostly shorter with end walls having small corner thickenings; stems brownish"	"Rhizomnium glabrescens"
6	"Leaves nearly orbicular; limbidium mostly not reaching leaf apex or sometimes one cell wide; plant green after drying; leaves not decurrent"	"Rhizomnium nudum"
6	"Leaves obovate, mostly more than 1.5:1; limbidium several cells wide at apex with costa percurrent or nearly so; dried older plant with a blue-green blush; leaves decurrent by means of a 1-2 cell wide strip that reaches nearly to base of next lower leaf"	"Mnium blyttii"