This species is a true Amblystegium, Bryol. Europ., and resembles very closely Ambtystegium Spruceii (Hypnum Conferva, Drumm. Musc. Amer. No. 190; Platydictya Spruceii, Berk.), particularly in its normally asymmetrical and cernuous capsule; differing mainly in the inflorescence, which in the latter species is dioicous.
Ambtystegium confervoides, Bryol. Europ., another very nearly related species, is a larger and more rigid plant, has a more pinnate ramification, longer and thicker branches, and leaves more crowded, appressed when dry, entire on their margins, and of a closer areolation: its capsule also is oblong and incurved.
Two other species of Amblystegium, A. subtile and A. tenuissimum are near allies of our plant; the first, however, is larger, and has shortly bicostate and entire perichætial leaves, an oblong-capsule, and a peristome without ciliolæ; in the second species (not found in this country) the capsule is oblong and erect, the perichætial leaves are costate beyond the middle, and the annulus is absent.
TAB. 120.—Hypnum minutissimum.
1. Planta naturali magnitudine.
2. Planta capsuligera et antheridiophora.
3. Pars ramuli.
4. Folia.
5. Folium areolationeni exhibens.
6. Folia perichætialia.
7. Capsula opcrculata.
8, 9. Capsulæ humidæ deoperculatæ.
10. Eædem siccæ evacuatæ.
11. Particula peristomii.
12. Dens ejusdem a latere visus.
13. Operculum.
14. Calyptra.
15. Flos masculus.
16. Perigoniale et antheridium.
