Part 2, 1913} LEUCOBRYACEAE 163 
Leaves more than two layers of hyaline cells in thickness near the base; chloro- 
cysts one half up the leaf median or nearest the ventral surface. 
Leaves in cross-section near the base mostly showing a thickness of 3 layers 
of cells across the median line of the leaf, usually 2 layers above and 
1 layer or sometimes 2 layers below the chlorocysts; thickest part of 
the leaf on either side of the median line with up to 6 or 7 layers of 
cells. (In the less robust forms of L. giganteum sometimes only 2 
layers are found across the middle of the leaf, but the greater length 
of leaf will distinguish it from others of our region with the exception 
of L. albicans.) 
Leaves 5-8 mm. long. 1. 
Leaves 14-22 mm. long; annulus wanting. 2. 
Leaves in cross-section near the base showing | layer of cells above and 1 or 
rarely 2 layers below the chlorocysts along median line of leaf. 
Thickest part of the leaf on either side of the median line near the base 
of mostly 2 layers of cells above and 2 layers below the chlorocysts. 
Leaves 8-14 mm. long with an ovate base 2-3 mm. long; annulus 
resent. ammo 3. L. albicans. 
Leaves from scarcely 2 up 4.5 mm. long from an ovate base narrowed 
to a subtubulose point scarcely as long as or often much shorter 
. glaucum, 
. giganteum., 
Sly 
than the ovate base. 4. L. albidum. 
Leaves mostly 5-7 mm. long, from an ovate base about 1 mm. long, 
narrowed to a subtubulose point 3-6 times as long. 1 5. L. crispum. 
Thickest part of the leaf near the base of 2 or 3 layers of cells above and 
3 or sometimes 4 layers below the chlorocysts. 
Leaves 5-10 mm. long, with a subtubulose point from a little longer 
than the ovate base to 2-3 times as long. 6. L. Antillarum. 
Leaves 3--4.5 mm. long, with a subtubulose point mostly slightly longer 
. than the more or less ovate -base. . L. Polakowskyi. 
Leaves only 2 layers of hyaline cells in thickness near the base; chlorocysts one 
half up the leaf much nearer the dorsal than the ventral surface. 8. L. Martianum, 
1. Leucobryum glaucum (L.) Schimp. Coroll. Bryol. 
Eur. 19. 1855. 
Bryunt glaucum ¥,. Sp. Pl. 1118. 1753. 
Dicranum glaucum Hedw. Fundam. 2:92. 1782. 
Leucobryum vulgare Hampe, Flora 20: 282. 1837. 
Pseudautoicous: male plants minute, from 2 to rarely 6 mm. high, growing on tufts of 
tomentum enclosed by perichaetial leaves of sterile flowers below fruiting branches; flowers 
mostly solitary, with antheridial leaves scarcely differentiated, containing 2 or 3 antheridia 
0.4 mm. long, with few paraphyses: fertile plants in compact, pale-yellowish to dull-green 
cushions, with branching stems up to 5 cm. or rarely 10 cm. or more high, bearing crowded, 
erect-spreading, sometimes secund leaves: stem-leaves 4-11 mm. long, from an ovate base 
narrowed to a subtubulose point of variable length with an acute, minutely denticulate, in- 
curved apex; costa in cross-section near the base showing mostly 6 layers of large, empty cells 
enclosing a median row of small, quadrate chlorocysts, usually 2 layers of large cells extending 
across the chlorocysts in the middle of the costa on the upper side and 1 layer on the lower side; 
hyaline blade of the lower part of the leaf about 5 cells wide on either side: seta dark-red, 
about 1.5 cm. long: capsule nodding, usually distinctly strumose, strongly curved and fur- 
rowed when dry, without stomata; annulus none; peristome-teeth divided to below the middle 
into slender papillose forks, the articulations below close, vertically striate; lid with a slender 
beak about the-length of the capsule: spores slightly rough, up to 16 » in diameter. 
TYPE LocaLiry: Europe. ; oe 
Digtrisution: Newfoundland to Minnesota, and southward to Florida and Louisiana; Bermuda; 
also throughout Europe. 
ILLUSTRATIONS: B.S.G. Bryol. Eur. fl. 97, 98; Lesq. & James, Man. l. 2. . 
Exsicc.: Ren. & Card. Musci Am. Sept. Exs. 277 (as L. albidum), 361; Sull. Musci Allegh. 168; 
Sull. & Lesq. Musci Bor. Am. 76; ed. 2. 97, 98, in part; Aust. Musci App. 99;,Macoun, Can. Musci 55; 
Drummond, Musci Am. 89, 
2. Leucobryum giganteum C. Miill. Syn. 1: 79. 1849. 
Leucobryum robustum Sull. Proc. Am. Acad. 5: 279, 1861. 
Pseudautoicous: male plants minute, usually 2-3 mm. high, borne on tomentum en- 
closed by the perichaetial leaves of the sterile archegonia or along the inner surface of the 
tubulose point of the stem-leaves; flowers solitary, the antheridial leaves few, ovate, acute, 
