The Manual of the Botany of the Northern United States / Including the District East of the Mississippi and North of North Carolina and Tennessee

by Asa Gray

5. Porella. Lower lobe ligulate. Perianth triangular, the third or odd angle ventral.

[++][++] Root-hairs rising from the lower lobes.

4. Radula. Perianth compressed. Underleaves none.

[+][+] Upper lobe smaller than the lower, or the two somewhat equal.

[++] Leaves succubous as to their lower lobes.

15. Scapania. Involucral leaves 2; perianth dorsally compressed, the mouth truncate, bilabiate, decurved.

16. Diplophyllum. Involucral leaves few; perianth erect, round, the mouth denticulate.

[++][++] Leaves transverse.

25. Marsupella. Perianth tubular or somewhat compressed. (Compare also Jungermannia § Sphenolobus.)

[*][*] Leaves palmately 3–4- (or many-) cleft.