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

[+] Divisions numerous, capillary. Plants large, usually in conspicuous mats.

6. Ptilidium. Leaves palmatifid with ciliate margins.

7. Trichocolea. Leaves setaceously multifid.

[+][+] Leaves 3–4-cleft or parted; plants small, mostly inconspicuous.

10. Lepidozia. Leaf-divisions two cells wide or more.

11. Blepharostoma. Leaf-divisions only one cell wide.

[*][*][*] Leaves entire, emarginate, or 2–3-toothed or -lobed.

[+] Leaves closely imbricate on short julaceous stems.

27. Gymnomitrium. Involucre double, the inner shorter.

[+][+] Leaves deeply bilobed.