Part 35

--LILIACEÆ.--]

This leathery parasite is not very particular as to its host. Quite a large number of trees of different species harbour it, notably the apple; next in favour are poplars, hawthorns, lime, maple, mountain-ash, and very rarely the oak. It has been suggested that the very fact of its extreme rarity upon oak gave oak-grown mistleto its sacred character among the ancient Britons.

=Meadow-Saffron= (Colchicum autumnale).

The Meadow-Saffron is more frequently known as the Autumnal Crocus, but we object to the name as conveying a wrong idea of the botanical characters of two distinct genera. Further, there is a true autumnal crocus (Crocus nudiflorus), though its claim to be considered British is open to doubt. Like Crocus, Meadow-Saffron has an underground solid stem (corm), resembling a bulb, and from this arise the flowers in succession from August to October. These flowers are of a pale purplish colour, and consist of a long slender tubular perianth, enlarging at its upper part into a bell-shape, and this portion is divided into six segments, to each of which a stamen is attached (Crocus has but three). The ovary lies deep within the calyx-tube, and from it arise three long thread-like styles, which are bent over near the tip, the inner side of which is the stigma.

The fruit develops during the winter, and by the spring is ripe. Then when the long, flat leaves make their appearance, the flower-stalk lengthens and brings the ripe capsule above the ground. Sometimes the flowers mistake the seasons and put in an appearance with the leaves in spring, but they are imperfect, and the perianth is greenish-white.

The name is from Colchis, where it is said to have grown abundantly.

=Hart’s-tongue Fern= (Scolopendrium vulgare).

Hitherto we have dealt only with flowering plants. In these sexual organs are borne in more or less conspicuous blossoms, and, as the result of fertilization of the ovules by the pollen, seeds are produced which give rise to plants exactly like that which bore them. Ferns produce an enormous number of minute bodies, called spores, which are incapable of developing directly into a plant similar to that by which they were produced; but on germination they give rise to a minute green scale, like a liverwort, upon the under surface of which sexual organs appear, and by the mingling of their cell-contents a true bud is formed, from which a true fern-plant is evolved. There are other important points upon which ferns differ from flowering plants, but it is not within the author’s province to deal with them here. Let it suffice to add that as a fruit-bearing organ the leafy portion of a fern differs greatly from the leaves of other plants. To prevent confusion it is termed a frond.

The Hart’s-tongue has a frond of very simple character--strap-shaped--consisting of a stout mid-rib (rachis), with a leathery green expansion on either side, the upper end tapering off to a point, the lower divided into two lobes. A large number of thick red-brown parallel ridges on the under surface will attract immediate attention. These are heaps of delicate capsules (sporangia), which contain the spores. The Hart’s-tongue is a plant of sandy or rocky hedgerows.

Scolopendrium officinale.

=Maidenhair Spleenwort.=

Asplenium Trichomanes.

--FILICES.--]

Nephrodium filix-mas.

--FILICES.--]

=Maidenhair Spleenwort= (Asplenium trichomanes).

A common plant locally on rocks and walls, having a slender dark-brown polished rachis and a large number of roundish-oblong leaflets (pinnæ), arranged pinnately on each side. The capsules will be found in short thick lines on the under surface. There is a similar species, the Green Spleenwort (A. viride), with a green, softer rachis and the pinnæ distinctly stalked, shorter and paler; growing on wet rocks in mountainous districts.

=Male Fern= (Nephrodium filix-mas).

In the Male-fern--so-called by our fathers owing to its robust habit as compared with the tender grace of one they called Lady-fern (Asplenium filix-fœmina)--we have an advance in the intricacy of frond-division. Our page is not sufficiently large to represent the whole of the frond, but the portion we give shows that the pinnæ are themselves again divided into pinnules. This fern grows to a great size, its rootstock very thick and woody, its fronds erect and three or four feet high. As a rule the rachis and its continuation below the leafy portion (stipes) are shaggy with loose golden-brown scales. The spore-capsules are in little round heaps in rows along the pinnæ, and each heap is covered by a thin kidney-shaped involucre. Note in the unrolling of a young frond how beautifully the whole is packed up. The lateral divisions of the pinnæ are rolled each on itself, then the pinnæ are rolled up from their tips toward the rachis, and finally the whole frond is coiled up from the tip downwards. This is the characteristic vernation of ferns, and differs greatly from the packing of undeveloped leaves in the leaf-buds of flowering-plants.

The genus Nephrodium (named from nephros, the kidneys, in allusion to the involucre) contains half-a-dozen other British species, of which the most frequent is the Broad Buckler Fern (N. spinulosum), with arching fronds, broad at the base, the stipes sparingly clothed with dark-brown scales. Pinnules toothed, the teeth ending in long soft points. Damp woods.

Mountain fern (N. oreopteris), with habit of Male fern, but stiffer, and of a yellow-green hue. Spore-heaps near the margins of the pinnæ. High hills and mountain pastures.

=Field Horsetail= (Equisetum arvense).

The Horsetails are a small group of flowerless plants, quite distinct from the ferns, though there are certain points in which some resemblance may be traced. We have eight British species out of twenty-five that are known to inhabit the earth. The most widely distributed of these is the Field Horsetail (E. arvense), which farmers regard as a pest. In common with the whole tribe it has a creeping underground rootstock, from which more or less erect jointed stems arise. If we break off one of these joints at its natural articulation we shall observe that the ends are solid, and that the upper extremity is crowned by a sheath ending in long pointed teeth, into which the lower end of the next joint fitted. This leaf-sheath, as it is called, is composed of a number of aborted leaves--the only vestiges of leaves the plant possesses. Just below the leaf-sheath a whorl of jointed branches is given off, each constructed in a manner similar to the upright stem. If now we cut our main joint across its middle with a sharp knife we shall find that it is tubular, a central cavity occupying about one-third of its diameter. Between this cavity and the exterior wall is a series of small tubes, somewhat egg-shaped in outline, the smaller end towards the central cavity; alternating with these and nearer the centre are a number of smaller circular tubes. This section should always be made when in doubt as to the species, for the shape and arrangement of these cavities differs in each, as do the external ridges. The accompanying cuts represent half-sections through the stems of the principal British species. In this species there are about a dozen blunt ridges on the stem, extending right to the points of the leaf-sheath. The branches are four-angled, solid, and jointed and sheathed like the main stem. The cells of the cuticle secrete silica in such quantity that the whole of the vegetable matter may be got rid of by maceration, yet the form of the stem will remain in this transparent skeleton of silica. Certain species are used for polishing metal, under the name of Dutch Rushes.

Equisetum arvense.

--EQUISETACEÆ.--]

Cladonia cornucopioides.

B.--=Wall-Lichen.=

Physcia parietina.