Part 36

--LICHENES.--]

1. Equisetum maximum. 2. ” pratense. 3. ” arvense. 4. ” sylvaticum. 5. ” limosum. 6. ” palustre. 7. ” hyemale.]

So far we have been describing what is known as the barren stem, because it ends in several unbranched joints, without any fructification. Before these barren stems appeared there arose from the rootstock a stem differing greatly in appearance, usually without branches, and lacking the green colouring matter (chlorophyll). It is pale brown in colour, of stouter build, but much shorter, for whereas the barren stem is about two feet in length, the fertile is only a few inches, or at most less than a foot. The leaf-sheath is longer, and the teeth frequently adhere two or three together. The stem terminates in a kind of cone, consisting of many whorls of flat scales, each supported by a central stalk, on the underside of which are arranged from six to nine capsules containing spores. These spores are very curious: they are globular in form, and invested with several coats, the outermost of which splits into four narrow strips, which are highly hygroscopic, and which remain attached to the spore at one point only. These elaters, as they are termed, are very sensitive to changes in the humidity of the atmosphere, as may be proved by breathing upon them, however slightly, when they will be seen (through the microscope) to be in active movement. In many ferns the spores require months to elapse before germination takes place; those of Horsetails will germinate in a few hours. Owing to its possession of chlorophyll the spore, if not placed in a situation suitable for germination, perishes in the course of a few days.

The name of the genus is from the Latin, equus, a horse, and seta, a bristle. The fertile stems appear in March and April, the barren ones at intervals later.

=Lichens= (Lichenes). Plate 126.

The rambler will meet with specimens of the Lichen tribes at every turn, when he has got fairly away from the smoke of towns. He will find them on the tree-trunks or rocks and walls, old posts and palings, on thatch and on the ground. Wherever they are found they may be accepted as certificates of the purity of the air. Formerly considered as a distinct type, they are now held by the advanced school of cryptogamic botanists as commensals, or partnerships formed between a fungus and an alga. They are usually thin crusts, consisting of an upper and a lower epidermis, formed of closely crowded cells, and to the lower layer rootlike filaments are attached. Between these layers are two differing elements; a loose stratum of green cells (gonidia), which are said to be algæ, and below these a layer of fungoid threads. The contention of the new school is that these algæ have been captured by a fungus and held in bondage, being forced to elaborate starch by means of their chlorophyll from the inorganic material obtained by the rootlike filaments, which starch the fungus is able to feed upon. Some of the green cells are pushed out from time to time invested with a few wisps of fungus-threads, and so reproduce the partnership. It is but right to add that some good authorities on this branch of botany decline to accept these views, and still regard lichens as independent organisms and not partnerships.

Hypnum triquetrum.

=Hair-Moss.=

Polytrichum formosum.

--MUSCI.--]

Amanita muscarius.

B.--=Edible Boletus.=

Boletus edulis.

C.--=Puff-ball.=

Lycoperdum gemmatum.

D.--=Chanterelle.=

Cantharellus cibarius.

--FUNGI.--]

The species are very numerous, but their identification is not easy, and requires serious application. The two figured are exceedingly common in some districts. Various species of Cup-moss (Cladonia) will be met on heaths, sandy hedge-banks, etc. They have a flat crust-like base, from which arise pale grey tubes or cups, bearing at their tips the bright scarlet, pinky-brown, or even black fruits. A more common form in woods and on banks is Cladonia pyxidata, with the tube greatly increasing in width upwards. Cladonia rangiferina is the well-known Reindeer-moss, of inestimable value in extreme Northern latitudes as the food of the useful animal whose name it bears; it may be found in abundance in this country on heaths and hillsides covering the ground beneath the heather.

The other species figured in our plate, the Wall-lichen (Physcia parietina), is also very common, forming the familiar orange stains upon walls and maritime rocks. A closely allied species, the grey Parmelia saxatilis, is common on tree-trunks: it has been used time out of mind in the production of a brownish-red dye for wools. Several others of the same genus are valuable in a similar direction: our own Parmelia perlata, which grows on tree trunks, is largely imported from the Canaries as a dye-weed, and has been sold at as high a rate as £200 per ton.

Lichens are generally of slow growth and long life. Mr. Berkeley kept watch upon a patch of Lecidia geographica for twenty-five years, and found little change in it all that time. The Rev. Hugh Macmillan recounts how he found on the top of Schiehallion a species of lichen encrusting quartz rocks, which exhibited beneath the lichen the marks of glacial action as distinct and unchanged by atmospheric effects as though the glacier had only passed over them yesterday. He suggests that the lichen may reckon its days back very nearly if not quite to the glacial period in Britain!

There are upwards of a thousand British species, and the best list of them will be found in “Crombie’s British Museum Catalogue of Lichens,” of which the first part was published in 1894.

=Mosses= (Musci). Plate 127.

Another important tribe of flowerless plants, to which we must be content with merely giving the general characters, for in a volume primarily intended as a guide to wild-flowers we must not occupy too much space with plants that do not produce flowers. At the same time, we believe the non-botanical among our readers will be glad to have a slight introduction, upon the strength of which they may cultivate the closer acquaintance of a most beautiful and interesting group of plants.

A. Three-cornered Hypnum (Hypnum triquetrum) is a common species on woodland banks, growing in branching tufts. The stems are well clothed with leaves, which consist of a single layer of cells; there is therefore no necessity for the breathing pores (stomates) found on the leaves of flowering plants and giving access to the tissues beneath the cuticle. The leaves of mosses are not provided with stomates; neither are they stalked, but attached directly to the stem by their base. From the sides of the stem at intervals a number of brown, hair-like threads are given off, and each of these ends in a brown, pear-shaped nodding organ, the spore capsule. These capsules are each closed with a lid (operculum), beneath which is a double row of teeth, their tips directed towards the centre of the mouth. When the spores are ripe the operculum is cast off, and these teeth erect themselves to allow the minute spores to escape. The teeth (forming the peristome) of mosses are always some multiple of four; in Hypnum each row contains sixteen.

B. Beautiful Hair-moss (Polytrichum formosum) represents another division of mosses in which the fruits are borne on the termination of the stem or principal branches. In an earlier condition than that figured the capsule is covered with a conical densely-hairy cap (calyptra); this is thrown off when the spores are ripe, the operculum follows and the spores are cast.

=Mushrooms and Toadstools= (Fungi). Plate 128.

We cannot pretend to do other than call the rambler’s attention to the interesting plants that are variously called mushrooms or toadstools, according to whether they are of the two or three species commonly eaten, or of the multitude concerning which the British public knows nothing, and therefore dismisses them as worthless toadstools.