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Tortula Hedwig, 1801.

The concept of the genus Tortula has changed radically in recent years as a result of the monumental work of Dr. Richard Zander. The newly circumscribed Tortula can be defined on the basis of broad, usually ovate to elliptic or obovate, leaves. The costal cross-section has a single abaxial stereid band, and most species have clear epidermis on both surfaces of the costa. Most of the larger sized members of the genus are now placed in the genus Syntrichia. Two genera of rather small plants, Desmatodon and Pottia are either not now recognized or have had many of their members transferred into the genus Tortula. Phascum is a genus of small mosses with sessile and cleistocarpous capsules but with leaf morphology similar to that of many species of Tortula. Zander incorporated the genus Phascum into Tortula, but we prefer to recognize Phascum.

Key to Tortula Etc.

Species included in this key are all in Pottiaceae:
Hennediella heimii (Hedwig) Zander
Hennediella stanfordensis (W. C. Steere) Blockeel
Leptophascum leptophyllum (C. Müller Hal.) J. Guerra & M. J. Cano
Tortula atrovirens (J. E. Smith) Lindberg
Tortula brevipes (Lesquereux) Brotherus
Tortula californica E. B. Bartram
Tortula euryphylla Zander
Tortula guepinii (Bruch & W. P. Schimper) Brotherus
Tortula inermis Bridel
Tortula leucostoma (R. Brown) W. J. Hooker & Greville
Tortula mucronifolia Schwägrichen
Tortula muralis Hedwig
Tortula nevadensis (Cardot & Thériot) Zander, not known from CA
Tortula obtusifolia (Schwägrichen) Matthieu
Tortula plinthobia (Sullivant & Lesquereux in A. Gray) Brotherus
Tortula protobryoides Zander
Tortula subulata Hedwig
Tortula systylia (W. P. Schimper) Lindberg
Tortula truncata (Hedwig) Mitten in Godman, not known from CA

A. Hyaline point consistently absent; sometimes mucronate to apiculate or with a few enlarged apical cells .....B
A. Hyaline point present on at least some leaves .....M

B. Leaf cells smooth to mammillose, or with a few small papillae in distal portion of leaf; cells of leaf margin typically somewhat smaller and thicker walled than adjacent laminal cells .....C
B. Leaf cells papillose, usually densely so; margin various .....F

C. Costa cross-section showing no stereid band or with only 1-4 such dorsal stereid cells; cells of leaf middle thin and bulging- vesiculose; margin crenulate-papillose .....Leptophascum: L. leptophyllum
C. Costa cross-section showing a clear dorsal stereid band; cells of leaf middle with somewhat thickened walls, not vesiculose; leaves entire or low dentate near the apex .....D

D. Leaf margins strongly recurved to revolute at least near base; plants mostly with stems more than 5 mm long with leaves conduplicate folded when dry .....Tortula mucronifolia
D. Leaf margins plane throughout; plants mostly smaller with leaves crumpled when dry .....E

E. Leaf margins entire throughout; peristome absent; deoperculate capsule hemispheric or nearly so .....Tortula truncata not known from CA
E. Leaf margins on well developed leaves with a few serrulations near the apices; peristome present; deoperculate capsule short cylindric, mostly about 2:1 .....Tortula nevadensis not known from CA

F. Leaf bordered by elongate cells to above the middle .....G
F. Leaf not bordered by elongate cells, or border restricted to leaf base .....H

G. Leaves mostly more than 3 mm long with entire or papillose-crenulate margins; plant autoicous and usually with sporophytes .....Tortula subulata
G. Leaves little more than 1 mm long with at least a few marginal cells enlarged into teeth; plant dioicous, unknown with sporophytes .....Hennediella: H. stanfordensis

H. Plants with a thick cushion of enlarged cells on the ventral surface of the costa at the distal end; plants of periodically dry soil in arid areas .....Tortula atrovirens
H. Ventral surface of costa plane or grooved, not convex .....I

I. Leaves deeply concave, rather closely comose, appearing somewhat bulbiform; leaf apex acuminate; capsules cleistocarpous .....Tortula protobryoides
I. Leaves not forming a strongly bulbiform cluster; leaf apex obtuse to mucronate; capsules stegocarpous .....J

J. Marginal cells throughout upper and median portion of leaf epapillose or nearly so, radically differentiated from the heavily papillose interior cells .....Hennediella: H. heimii
J. Marginal cells not differentiated from interior laminal cells .....K

K. Leaves folded lengthwise and variously twisted when dry .....Tortula inermis
K. Leaves little distorted when dry .....L

L. Median leaf cells typically less than 12 µm in diameter; plant of soil banks in lowland oak savannahs and grasslands .....Tortula obtusifolia
L. Median leaf cells typically more than 15 µm; plant of wet soils in high montane regions .....Tortula euryphylla

M. Leaf cells typically smooth .....N
M. Leaf cells papillose, usually densely so .....O

N. Capsule systylious and with peristome short, not much spirally twisted; leaf cells mostly 2:1, to 20 µm long .....Tortula systylia
N. Capsule with operculum free from the columella; peristome long and twisted in several spirals; leaf cells nearly isodiametric, mostly over 25 µm wide .....Tortula californica

O. Leaves bordered with thicker-walled cells or marginal cells with corner-thickenings; plant epiphytic or on cement or brick walls .....Tortula muralis
O. Leaves not so bordered; plant of calcareous or desert soil .....P

P. Marginal cells more lightly papillose than adjacent cells; leaves seldom more than 1.5 mm long; plant mostly on periodically dry lowland soils near the coast .....Tortula guepinii
P. Marginal cells not more lightly papillose; leaves mostly more than 2 mm long .....Q

Q. Leaves, disregarding the awn, narrowed to apex, usually acute .....R
Q. Leaves, disregarding the awn, rounded to emarginate at apex .....S

R. Leaves broadest near the base; juxtalaminal, abaxial cells of costa usually enlarged and yellowish-brown to orange in a pair of uniseriate rows on each side of costa; marginal recurvature at least at mid-leaf performing a complete spiral .....Pseudocrossidium: P. crinitum
R. Leaves ovate to ovate-lanceolate, broadest at or near the middle, juxtalaminal, abaxial cells of costa not so differentiated; marginal recurvature less pronounced .....Tortula leucostoma

S. Median cells mostly more than 15 µm broad; plants of rather moist habitats at high elevations; dry leaves weakly crispate, not at all carinate .....Tortula euryphylla
S. Median cells mostly smaller; plants of lower elevations; dry leaves weakly carinate, mostly twisted around stem .....T

T. Awn mostly less than 2 mm long with leaves often simply mucronate; mucro or awn irregularly low serrulate near apex; peristome without a basal membrane .....Tortula plinthobia
T. Awn mostly about 4 mm long with that awn entire or nearly so; peristome with filiform teeth arising from a clear basal membrane .....Tortula brevipes

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