Eurhynchium Bruch & W. P. Schimper in Bruch & W. P. Schimper, 1854.

The genus Eurhynchium is basically a Brachythecium with a long rostrate operculum. We must remember that early muscologists saw the sporophyte as the moss analog of the flower and fruit of a flowering plant. The excessive importance of the sporophyte in mosses is being tempered by modern taxonomic treatments, and we are attempting to assimilate the major taxonomic reapportionments in Ignatov and Huttunen (2002). This work will surely lead to readjustment of the taxonomies in our present work, but the changes are so numerous and significant as to require a period of fermentation prior to adoption.

Key to Eurhynchium Etc.

In the key that appears below we have included pleurocarpous mosses with costate leaves. Except for Steerecleus, the plants in this key have elongate median cells but drastically shorter cells of the distal portion of each leaf.

Species included are all in Brachytheciaceae:
Eurhynchium hians (Hedwig) Sande Lacoste
Eurhynchium pulchellum (Hedwig) Jennings
Eurhynchium striatum (Schreber ex Hedwig) W. P. Schimper
Kindbergia oregana (Sullivant) Ochyra
Kindbergia praelonga (Hedwig) Ochyra
Platyhypnidium riparioides (Hedwig) Dixon
Scleropodium colpophyllum (Sullivant) Grout
Steerecleus serrulatus (Hedwig) H. Robinson

There are only a few gametophytic features allowing recognition of Eurhynchium and its allies. Kindbergia is a poorly differentiated genus recognizable by the squarrose stem leaves that are radically broadened relative to the more narrow and patent branch leaves; our two species of Kindbergia are easily recognized due to their branching pattern and leaf arrangement. Platyhypnidium is similarly a poorly differentiated genus recognizable by the almost cordate leaves on this aquatic moss. Steerecleus is a third segregate from Eurhynchium primarily distinguished by the complanate growth habit.

A. Plants regularly pinnate, often bi- or tri-pinnate; leaf margin decurrent .....B
A. Plants irregularly, often sparingly branched; leaf decurrency short and often inconspicuous .....D

B. Leaves of stems only gradually larger than those of branches, not squarrose; leafy stems mostly prostrate .....Eurhynchium striatum
B. Leaves of stems radically and abruptly larger, broader and more decurrent than those of branches; leafy stems usually arching above the sustrate .....C

C. Plant regularly plumose with a single main stem from which arises shorter, nearly unbranched, lateral stems; plant mainly of coastal moderately low elevation sites .....Kindbergia: K. oregana
C. Plant irregularly branched or tri- to tetra-pinnate; plant mainly of higher elevation, or of deeply shaded sites .....Kindbergia: K. praelonga

D. Plant complanate-foliate; leaves with a well-demarcated and laterally twisted acumen and with the cells in that acumen mostly more than 4:1 .....Steerecleus: S. serrulatus
D. Plants not complanate; leaves not acuminate or with the acumen poorly defined; cells in acumen various but often very short .....E

E. Leaves orbicular; leaf apices not at all acuminate, plant aquatic .....Platyhypnidium: P. riparioides
E. Leaves longer than broad; leaf apices blunt to obtuse; plant on mesic to rather dry sites .....F

F. Leaves deeply concave with basal cells rectangular across the entire base .....Scleropodium: S. colpophyllum
F. Leaves not deeply concave; differentiated cells of leaf base confined to alar region .....G

G. Leaves ovate-lanceolate with a short but blunt acumen; seta smooth .....Eurhynchium pulchellum
G. Leaves elliptic to elliptic lanceolate with a broadly acute to almost obtuse apex; seta papillose throughout .....Eurhynchium hians