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Herbarium — Part 14

The spore-cases are leathery, pear-shaped, narrowing down to a solid neck (collum) with breathing pores (stomata) on the surface; they are regular or rarely recurved. They have convex lids with a tiny blunt point at the centre and are borne on long and stout pedicels.

The peristome is double, the outer teeth are long and linear or lance-shaped, marked with many cross-bars internally, prominent below; the inner membrane is divided above into keeled segments adherent to or free from the teeth, and separated by usually two to five hair-like divisions (cilia) mostly with spurs attached at intervals to the margin.

The annulus is large, compound, and rolls back as the lid falls.

There are 800 or more described species, one hundred and thirty-two in North America.

The Silvery Bryum, Bryum argenteum, Linn.

Habit and habitat.--In green or silvery-white irregular cushions, on exposed ground, roofs, pavements, burnt places and almost everywhere except on trees. Very common.

Name.--The specific name refers to the colour. Latin argenteum, silvery. Johann Dillenius, a German botanist, called this moss "Catkin-stemmed Silver Moss" from its resemblance to the catkins of a poplar tree.

Plant (gametophyte).--Stems short, 1/2 to 1 inch high covered with root-like filaments; there are numerous shining catkin-like branches, each tipped with a brush of hairs.

Leaves.--At the apex of the stem, oblong-lance-shaped, taper-pointed, silvery-gray; stem and branch leaves broadly oval, or inverted oval, deeply concave; apex abruptly pointed; margin entire, flat; vein (costa) vanishing above the middle; cells loose.

Habit of flowering.--Male and female on separate plants (dioicous). Male flowers terminal.

Veil (calyptra).--Narrowly hood-like, falling before the spore-case ripens.

Spore-case.--Abruptly pendulous, oblong, deep purple when ripe, constricted under the mouth when old.

Pedicel.--Long and curved at the summit, 1/2 inch high, dark red when mature.

Lid (operculum).--Convex, slightly pointed, dark-orange.

Teeth (peristome).--As in the genus. Inner membrane yellow.

Annulus.--Present.

Spores.--Mature in fall and winter. Rarely fruiting in Great Britain.

Distribution.--Found in America, Europe and Asia. This is one of the five mosses which Sir Wm. Jackson Hooker found in the early part of the 19th Century at "Ultima Thule" of Antarctic vegetation.

The Rose Bryum, Bryum roseum, Schreb.--See Plate XVIII.

Habit and habitat.--Bryum roseum is one of the largest and showiest of the Bryums known outside the tropics. It is found in shaded woods at the bases of trees and decayed logs. Under favourable circumstances this species forms tufts, but usually the plants are scattered among other mosses.

Name.--The specific name refers to the rose-like arrangement of the crown leaves, Latin roseus, a rose.

Plant (gametophyte).--Fine and large, stems 1 to 2 inches long, with few branches; creeping stems (stolons) present, from which new plants arise.

Leaves.--At the apex crowded to form a rosette, each leaf spatulate; apex taper-pointed; margin acutely toothed from the middle upward, reflexed to the base, wavy when dry; vein (costa) broad and reddish at the base, narrowed upward and produced beyond the apex; cells loose and filled with chlorophyll. Stem-leaves lying close to the stem, oblong-lance-shaped, small and thin.

Habit of flowering.--Male flowers in separate tufts from the female flowers (dioicous), arranged at the apex of the stems and surrounded with radiating leaves.

Veil (calyptra).--Split up one side.

Spore-case.--Single or in clusters, oblong-conical, pendent, and slightly incurved, sold and not constricted under the mouth when dry.

Pedicel (seta).--Dark purple, long and solid. 1 to 1 1/2 inches high.

Lid (operculum).--Slightly convex with a tiny nipple in the centre, dark-purple.

Teeth (peristome).--Very long, inner segments orange-coloured, perforated along the keel.

Annulus.--Compound, rolling back as the lid falls.

Spores.--Mature in autumn.

Distribution.--On the Eastern and Western slopes of North America, also in Europe, Asia and Africa.

Genus MNIUM, Linn.

The species of the Genus Mnium are handsome mosses, usually tall and robust, with large, translucent leaves. They may be looked for about the bases of trees, on lawns, along roadsides, and in damp woods. They are especially attractive on the banks of mountain brooks or in the cool water of bubbling springs. The beginner may recognise some members of the genus by the dainty rosettes on the summits of the male plants, each rosette made of pale-green leaves with a beaded centre of darker green. Some species have the fertile stems erect with branches growing from near their bases or from creeping stems. The branches are often different from the main stems, being fernlike, prostrate, or curved with rooting tips so as to form successions of miniature arches.

The great Swedish botanist, Carolus Linnaeus, named the group from the Greek an ancient word for "moss."

The leaves of all the Mniums are dainty and fresh and their cell-structure and their colour are so delicate that it will repay one to examine them with a hand lens or the low power of a compound microscope. The leaves are usually large, rounded, more or less elliptic or tongue-shaped; the margin usually has a distinct border and is frequently spiny toothed; the vein either vanishes below or extends beyond the apex; the cells are smooth, rounded-hexagonal or rarely elongated.