Subject to considerable variation in size, habit, acnmi nation of leaf, &c. Not easily distinguished from Hypnum salebrosum, Hoffm., except by its dioicous inflorescence and usually more slender subcrect and less curved capsule.
The foregoing description and the drawings for Plate 115 are from specimens labelled "H. 20. Coll. Dewey." in the Herbarium of Dr. Torrey. Bridel (Bryol. Univ. 1. c.) refers to North American specimens from Torrey thus labelled as the materials on which he established his Hypnum lætum; hence there can be little question that the specimens first mentioned are also authentic for the true Hypnum lætum, Brid., a species about which some doubts have heretofore prevailed.
TAB. 115.—Hypnum lætum.
1, 2. Plantæ femineæ et masculæ naturali magnitudine.
3. Pars ramuli.
4, 5, 6. Folia ejusdem.
7, 8, 9, 10. Portioncs folii arcolationem exhibentes.
11. Sectiones transversales folii.
12. Perichsetium cum pedicelli basi.
13. 14. Folia perichætialia.
15, 16. Capsulæ operculatae.
17. Particula peristomii.
18. Sectio verticalis ejusdem.
19. 20. Operculum et calyptra.
21. Perigoniale et antheridium cum paraphysi.
