Lescuraea Bruch & W. P. Schimper, 1851.

All our species of Lescuraea are treated in the majority of recent works as a separate genus, Pseudoleskea. We are decidedly unconvinced that mere reduction of the peristome (Lescuraea) is adequate basis for separating a taxon from plants with a typical Hypnobryalean peristome (Pseudoleskea). Our species of Lescuraea, in our broadened sense, grow primarily on seasonally moist rock outcrops and boulders in montane regions. Lescuraea stenophylla is, however, primarily an epiphyte especially regular on the limbs of Alnus in areas where it is weighted down to the ground by the heavy snows of winter.

Key to Lescuraea Etc.

Mosses treated in this section are pleurocarpous, often julaceous mosses with elliptic to short rectangular, rather thick-walled cells and mostly with a large group of thick-walled quadrate cells. All these plants are prostrate on the substratum, and this separates them from the plants with similar leaf areolation treated in this paper under Antitrichia. Many of the plants treated here have leaf-like paraphyllia obvious on the surface of the denuded stem. Most of the plants treated here have papillose median cells, some species with those papillae over the lumen center and some over the distal ends of the cells.

Species included in this key are in Leskeaceae, except Iwatsukiella and Pterigynandrum (Pterigynandraceae), and Tripterocladium (Hypnaceae):
Iwatsukiella leucotricha (Mitten) W. R. Buck & H. Crum, not known from CA
Leptopterigynandrum austro-alpinum C. Müller Hal.
Lescuraea atricha (Kindberg in Macoun & Kindberg) E. Lawton, not known from CA
Lescuraea baileyi (Best & Grout in Grout) E. Lawton, not known from CA
Lescuraea incurvata (Hedwig) E. Lawton
Lescuraea pallida (Best) Norris & Shevock
Lescuraea patens (Lindberg) Arnott & C. E. O. Jensen
Lescuraea radicosa (Mitten) Mönkemeyer
Lescuraea saviana (De Notaris) E. Lawton
Lescuraea stenophylla (Renauld & Cardot) Lindberg
Leskea polycarpa Ehrhart ex Hedwig
Pseudoleskeella serpentinensis P. Wilson & Norris
Pterigynandrum filiforme Hedwig
Tripterocladium leucocladulum (C. Müller Hal.) A. Jaeger

A. Costa weak, usually ending at or before mid-leaf, often distally forked; plant typically at least somewhat julaceous .....B
A. Costa stronger, extending to or beyond the base of the acumen .....F

B. Leaves with a hyaline awn; plant of foggy mountain ridges in northwestern Oregon .....Iwatsukiella: I leucotricha not known from CA
B. Leaves without such an awn .....C

C. Paraphyllia present, foliose to variously lobed; median leaf cells prorate at both ends on dorsal leaf surface; costa absent or short and double; plants mostly rather irregularly branched .....Pterigynandrum: P. filiforme
C. Paraphyllia absent; costa extending to near mid-leaf, sometimes forked; median leaf cells smooth or obscurely papillose; plants closely pinnately branched .....D

D. Leaf cells with cuticular verruculosities (view under high magnification and low light intensity); costa distally forked; leaves somewhat falcate .....Leptopterigynandrum: L. austro-alpinum
D. Leaf cells smooth; costa forked or not; leaves mostly symmetric .....E

E. Plants mostly with a russet to reddish blush; costa broad and flattened, forked distally; median and more distal cells of leaf seldom more than 3:1 .....Pseudoleskeella: P. serpentinensis
E. Plant green to brownish; costa slender, not forked distally; median and more distal cells of leaf at least in part more than 4:1 .....Tripterocladium: T. leucocladulum

F. Cells strongly unipapillose over the center of the lumen .....G
F. Cells smooth or with low papillae over the cell ends .....H

G. Leaf margins strongly recurved from base to middle of leaf or beyond; some cells in the leaf middle 2:1 .....Lescuraea patens
G. Leaf margins plane or recurved only near the base; all median cells isodiametric .....Leskea: L. polycarpa

H. Paraphyllia absent; juxtacostal cells of leaf base longer than the median cells .....Lescuraea baileyi not known from CA
H. Paraphyllia present, easily seen on stems and branches after removal of leaves .....I

I. Base of acumen of branch leaves with a recurvature that specially separates that acumen from the rest of the leaf .....J
I. Leaf margin recurved primarily at the base with acumen not so defined .....K

J. Leaves gradually narrowed to a long acumen that nearly equals or exceeds the length of the rest of the leaf; leaves mostly straight and symmetric; plant mostly corticolous in alder groves at high elevations .....Lescuraea stenophylla
J. Leaves with the acumen shorter; leaves somewhat falcate by reason of the obliquely oriented acumen; plant epipetric .....Lescuraea saviana

K. All cells of the acumen shorter than 4:1; walls of median cells mostly with lumen:wall ratio less than 3:1 .....L
K. At least some cells in acumen more than 4:1; lumen:wall ratio of median cells more than 5:1 .....M

L. Median cells of stem leaves, sometimes also of branch leaves pitted; all alar cells quadrate to short rectangular .....Lescuraea atricha not known from CA
L. Median cells of stem leaves not pitted; some of the alar cells transversely elongate .....Lescuraea incurvata

M. Leaves quite strongly concave; branches ascending to erect; cells pellucid and somewhat bulging; plant of high mountain sites in the Sierra and Cascades .....Lescuraea pallida
M. Leaves not strongly concave; stems and branches mostly prostrate to decumbent; cells rather opaque; plant of montane sites in the Klamath Range .....Lescuraea radicosa