Drepanocladus (C. Müller) G. Roth, 1899.


Key to Drepanocladus Etc.

Mosses treated in this section are costate pleurocarps of wetland habitats. They have smooth, elongate cells and their leaf apices are acute to acuminate. Most have enlarged alar cells, and some have those cells extending all the way to the costa.

Species included in this key are in Campyliaceae except Cratoneuron (Cratoneuraceae); Leptodictyum (Amblystegiaceae) and Palustriella (Helodiaceae):
Cratoneuron filicinum (Hedwig) Spruce
Drepanocladus aduncus (Hedwig) Warnstorf
Drepanocladus capillifolius (Warnstorf) Warnstorf
Drepanocladus crassicostatus Janssens not known from CA
Drepanocladus polycarpos (Blandow ex Voit) Warnstorf
Drepanocladus sordidus (C. Müller Hal.) Hedenäs in W. R. Buck
Hamatocaulis vernicosus (Mitten) Hedenäs
Leptodictyum humile (Palisot de Beauvois) Ochyra
Leptodictyum riparium (Hedwig) Warnstorf
Palustriella commutata (Bridel) Ochyra
Palustriella falcata (Bridel) Hedenäs not known from CA
Sanionia uncinata (Hedwig) Loeske
Warnstorfia exannulata (Bruch & W. P. Schimper) Loeske
Warnstorfia fluitans (Hedwig) Loeske

All of the plants in this section have traditionally been considered a part of a family Amblystegiaceae, a family more recently split by such workers as Ochyra and Hedenäs. With the exception of Palustriella and Cratoneuron, the mosses included here were traditional placed together in a large genus, Drepanocladus. Palustriella and Cratoneuron were treated separately under the larger genus, Cratoneuron. The reason for the separation of Cratoneuron derived from the presence of paraphyllia, but those paraphyllia are often scarce and difficult to find.

A. Leaves longitudinally plicate, mostly falcate-secund .....B
A. Leaves of wet or dry plant not plicate or, if so, not falcate .....E

B. Alar cells very thin-walled and hyaline in a strongly demarcated region that extends to the costa; foliose paraphyllia scattered over the stem (especially visible near the stem apex); at least the basal cells with distal prorations ..... B2
B. Alar cells not inflated and hyaline, or with the inflated cells in a smaller group; paraphyllia not present; none of the cells prorate .....D

B2. Paraphyllia lanceolate, more than one cell wide except terminal cell .....Cratoneuron: C. filicinum
B2. Paraphyllia linear, only one cell wide for several cells distally .....C

C. Stem leaves deltoid-triangular with a somewhat cordate base, abruptly narrowed near the leaf middle into a long acumen; alar cells forming a large group in the cordate base .....Palustriella: P. commutata
C. Stem leaves lanceolate and falcate, gradually narrowed from near the base to the long acuminate apex; alar cells forming a small group to 5 cells long at margin .....Palustriella: P. falcata not known from CA

D. Stem cross-section with an obvious hyaloderm; leaves falcate-secund from the base; plant never with a reddish pigmentation, autoicous .....Sanionia: S. uncinata
D. Hyalodermis absent; leaves straight in proximal 1/2, becoming falcate distally; plant mostly with a reddish pigmentation, dioicous .....Hamatocaulis: H. vernicosus

E. Alar cells inflated and extending nearly or completely across the leaf base; plant aquatic or in seepages .....F
E. Alar cells not in such a large group; habitat various .....K

F. Plant typically brownish-green to purple or reddish; leaves with nematogons on each side of the costa, these nematogons appearing as empty cells strongly differentiated from the highly pigmented adjacent cells; plant mostly in running water of small streams .....Warnstorfia: W. exannulata
F. Plant typically green to glaucous-green although sometimes darker due to a covering of sediments, never reddish or purple; plant without nematogons on the leaves; mostly in seepages and slow-flowing to stagnant waters .....G

G. Leaf margin serrate to serrulate; leaves broadly ovate, about 2:1; lanceolate to filamentous paraphyllia normally sparse but present on well-developed stems; plants of calcareous seepages .....Cratoneuron: C. filicinum
G. Leaf margin absolutely entire, even at apex; leaves ovate-lanceolate, more than 3:1; paraphyllia absent; plant of slow-flowing or stagnant waters .....H

H. Costa percurrent to excurrent .....Drepanocladus capillifolius
H. Costa ending somewhat before the apex .....I

I. Plant with quadrate or very short rectangular cells in 1-4 rows immediately above the alar region .....Drepanocladus polycarpos
I. Alar region not set off by rows of short cells .....J

J. Leaves typically falcate-secund with acumen not well-demarcated from the rest of the leaf .....Drepanocladus aduncus
J. Leaves straight with acumen well-demarcated .....Campylium: C. polygamum

K. Terminal cell of leaf 1.5-3:1; alar cells only gradually differentiated from adjacent laminal cells .....L
K. Terminal cell of leaf longer and not much differentiated; alar cells somewhat different from adjacent laminal cells .....M

L. Plant mostly growing submerged in water or on frequently submerged objects; leaves obliquely attached to stem; median leaf cells mostly more than 10:1 .....Leptodictyum: L. riparium
L. Plants growing on mesic or very wet habitats, seldom submerged; line of leaf insertion at a right angle to the long axis of the stem; median leaf cells seldom more than 8:1 .....Leptodictyum: L. humile

M. Alar cells thin-walled and inflated; leaf margins serrulate, often minutely so; nematogons present as clear cells near costa in distal portion of leaf .....Warnstorfia: W. fluitans
M. Alar cells not in an a well-demarcated area of inflation; leaf margins entire, incurved in distal portions of leaf; leaf without nematogons .....N

N. Outer cells of stem cross-section somewhat enlarged relative to adjacent, more interior cells; proximal 1/2-2/3 of leaf elliptic and symmetrical with only the distal portion of leaf curved in a falcate manner; plant reddened throughout .....Limprichtia: L. revolvens
N. Outer several rows of cells in stem cross-section markedly smaller than more interior cells; leaves falcate throughout or straight; plant green to brown .....O

O. Alar cells only gradually differentiated; costa of stem leaves mostly occupying more than 1/4 of leaf base, bulging on both surfaces of the leaf .....Drepanocladus crassicostatus
O. Alar cells thick-walled and incrassate; well-demarcated from other basal cells; costa more narrow, bulging abaxially if at all .....Drepanocladus sordidus