78. Genus PTEROGONIUM, Swartz. 
Whole Plant — Perennial, erect, slender, tufted, branched, arched, naked below, light or yellowish green, from 1 inch 
to 2 inches in height. 
Stem — Slender, with fasciculate filiform branches arched above, naked below. 
Leaves — Ovate, imbricated, spreading, concave, acuminate, yellowish-green, glossy, margin plane at the centre and base 
of leaf, apex serrated, two nerved, short ; areoloe small, elliptical, or hexagonal. 
iNrLORESCENCE — Dioicous. 
Barren Floiver (Antheridia) — ) ^ .„ 
Fertile Flotver (Archegonia)- j Gemmiform. 
Vaginula — Oblong. 
Capsule — Erect, oblong, reddish-brown, on a long slender fruit stalk. 
Calyptra — CucuUate, sometimes slightly hairy. 
Operculum — Conical at the base, beak oblique. 
Peristome — Double, composed of 16 outer pale yellow lanceolate teeth, trabeculated, and 16 inner narrow 
processes. 
Annulus — Fragmentary, obscure. 
Spores— Small. 
General Habitat — On walls, shady rocks, and the bark of trees in mountainous districts ; rare in fruit. Fruit : — Spring 
and Autumn. 
Species Illustrated — Pterogonium gracile (Swartz), and Pterogonium flliforme (Hedw.)— in part. 
Reference to Plate — a, Plant, natural size; P. gracile, h, Stem leaves, X 1-in. ; c, Apex of leaf, same, X i-in.; d. 
Central cells of leaf of same, X i-in. ; /, Capsule of same, X 2-in. ; ff, Capsule, X 2-in. ; g, Teeth of 
peristome, X i-in. ; P. Jiliforme, bh, Stem leaf, X 1-in. ; cc, Apex of leaf, X ^-in. ; dd, Central cellules 
of leaf, X i-iti. ; ff, Capsule and Operculum, X 2. in. 
This genus is represented in Britain by two species. 
79. Genus ISOTHECIUM, Bridel 
Whole Plant — Perennial, growing in tufts on trunks or branches of trees, fruiting freely ; colour yellowish-green ; from 
1 inch to 2 inches in height. 
Stem — Somewhat dendroid from a creeping rhizome with incurved fasciculate branches. 
Leaves — Ovate-lanceolate, or ovate-oblong, concave, more or less acute, serrated at the apex, nerve single or forked, 
reaching almost to the apex, areolae elliptical. Perichaetial leaves ovate, acuminate, erect. 
Inflorescence — Dioicous. 
Barren Floiver (Antheridia) — Gemmiform, axillary. 
Fertile Flower (Archegonia). 
Vaginula — Oblong. 
Capsule — Erect, symmetrical, slightly bent, reddish-brown, on a curved elongated fruit stalk. 
Calyptra — Cucullate. 
Operculum — Conical, with an oblique beak. 
Peristome — Double, composed of 16 outer pellucid yellow teeth, having a medial line ' inner teeth frequently 
absent. 
A^mulus. — " Dehiscent." 
Spores — Small, yellow. 
General Habitat— On rocks and trunks of trees, not uncommon. Fruit : — October and November. 
Species Illustrated — Isothecium myurum (Bridel), Hyjjnum curvatum (Swartz). 
Reference to Plate- — a. Plant, natural size; 6, Stem leaf, X 1-in.; bh, PerichfBtial leaf, X 1-in.; c, Apex of stem leaf, 
X i-in. d, Central and basal cellules, X i-in; e. Outer and inner teeth of Peristome, X i-in. ; /, 
Capsules, X 1-in. ; g, Operculum, X i-in. ; 7i, Spores, X i-iu. ; i, Yaginula, X l-in- 
This genus is represented in Britain (according to Hobkirk) by the species figured. Wilson, in " Bry. Brit.," enumerates 
three species, which include Eurynchium myosuroides (Schmp.), and Thamnium alopecurum (Schmp.). — See 
Plate XXII. 
80. Genus CLIMACIUM, W. & Morli. 
Whole Plant — Perennial, erect, shrub-like, terminated with a tuft of branches, bearing numerous capsules, which arise 
from their base on long fruit stalks, from 3 inches to 4 inches in height. 
Stem — Tall, erect, lower part bare of branches, thickly branched at the summit; colour yellowish-green. 
Leaves — Small and scale-like on the stem, branch leaves ovate-lanceolate, plicate, concave, nerve reaching nearly to the 
summit, slightly serratulate at the apex, areolse hexagonal above, elongate, narrow at the base. Perichaetial leaves 
lanceolate, nerveless, entire. 
Inflorescence — Dioicous. 
Barren Flower (Antheridia) — ■) „ .„ 
Fertile Floiver (Archegonia)— j ^emmiiorm. 
Vaginula — Oblong. 
Capsule — Erect, cylindrical, on a long fruit stalk ; colom* bright chesnut. 
Calyptra — Dimidiate. 
Operculum — Conical, erect. 
Peristome — Double, composed of 16 long red lanceolate, trabeculated outer teeth with a medial line, and 16 
linear yellow inner ones. 
Annulus — None. 
Spores — Very small, greenish-yellow. 
General Habitat — Damp meadows and shady places and the borders of bogs. Fruit rather uncommon. — October, 
November. 
Species Illustrated — Climacium dendroides (Web. andMorh.) 
Reference to Plate — a, Plant, natural size; aa, Vaginula and perichaetial leaves, X 2 -in.; h. Branch leaves, X 1-in.; bh, 
Perichastial loaf, x 2-in.; c. Apex of stem leaf, X i-in.; d. Mid-leaf cellules, X y-in.; dd. Basal 
cellules, X i-in. ; e. Outer and inner teeth of peristome, X i-in. ; ee, same, X 4-in. ; /, Capsules, 
X 2-in. ; h, Spores, X ^-in. 
This genus is represented in Britain by the species figured. 
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