Bryophyte

“ In the Bryophytes the distinguishing characteristics are more constant and well-defined than in the Thallophytes. In the former the plant never consists of a single cell or coenocyte, but is always multicellular, and exhibits in most cases a definite physiological division of labour as expressed in the histological differentiation of distinct tissue-systems. In the Thallophytes there is no true alternation of generation in the same sense as in the Mosses and Liverworts and in the higher plants. ”

“ This surface layer in the typically subaerial “shoot” of the sporophyte in Pteridophytes and Phanerogams is known as the epidermis, though the name is restricted by some writers, on account of developmental differences, to the surface layer of the shoot of Angiosperms, and by others extended to the surface layer of the whole plant in both these groups. On the other hand, we have (2) an internal differentiation of conducting tissue, the main features of which as seen in the gametophyte of Bryophytes have already been fully described. ”

“ The appearance of a work on the Hepaticæ so soon after the publication of the Manual of N. A. Mosses will give students of the Bryophytes great assistance, and, with the author, we hope "that it may serve as a stimulus to more work in this direction, and lay in store material for a more critical examination of this group in the future." "No attempt has been made to publish new species, the writer believing that too many have already been described from insufficient data, and considering it far more necessary to set in order those already published." ”

“ Nevertheless all the great groups of plants, viz. the Thallophytes (algæ, fungi) , the Bryophytes (mosses, liverworts) , the Pteridophytes (ferns, horsetails, lycopods) , and the Spermatophytes (gymnosperms, angiosperms) have left some record.
The contribution of the Thallophytes (algæ, fungi, bacteria) .—The Thallophytes embrace the simplest types of plants, and are probably the nearest present representatives of the ancestral forms. Some of them are minute one-celled organisms, as simple as an organism can well be conceived to be. ”

“ Neither the Thallophytes, Bryophytes, nor Pteridophytes, nor all combined, approach the Spermatophytes in food value for the higher types of animal life, and it is doubtful whether the higher evolution of the land animals could have taken place without the previous introduction of the seed plants. It will be noted in the historical narrative that the great placental group of mammals came in and deployed with marvelous rapidity, as geological progress goes, soon after the Spermatophytes became the dominant form of vegetation. ”

“ The plant-body (gametophyte) in the Musci consists of a stem bearing thin leaves, usually spirally disposed, rarely in two rows. The internal differentiation of the stem is generally well marked, and in some cases is comparable in complexity with the structure of the higher plants. A protonema arises from the spore, having the form of a branched filamentous, or more rarely a thalloid structure. Reproduction as in the group Bryophyta.
Mosses like Liverworts have an extremely wide distribution, and occur in various habitats. ”

“ I am afraid it has been rather a difficult history to follow step by step, and yet it is perfectly clear when once we master the succession of growths. Starting from a spore, the thread-mass or protonema gives rise to the moss-stems forming the dense green carpet, then the green flowers on some of the leaf-stems give rise to a plant-egg, which roots itself in the stem, and grows into a perfect plant without leaves, bearing merely the urn in which fresh spores are formed, and so the round goes on from year to year. ”

“ The Seed-bearing plants form the most numerous group in existence, not less than 120,000 species being known. The subkingdom was formerly known as Phanerogamia, or Phaenogamia and more recently as Anthophyta, this term signifying the presence of flowers, which characterizes most of the group. But the consideration that the spore-bearing organs of the Pine Family cannot well be regarded as flowers, and the fact that the production of seeds is the most characteristic difference between these plants and the Pteridophyta, are reasons which have led to the acceptance of the term here adopted. ”

“ This species forms in the course of its growth two kinds of leaves; the entire leaves of the young plant, which are shaped like those of the common live-forever, and, at a later stage of growth, cleft leaves. The two kinds of leaves are not equally competent to form buds, but the property is a peculiarity of the cleft ones. When we gently draw the hand over a well-grown plant of Bryophyllum, we will find the feathered leaves falling like ripe fruits to the ground, while the entire leaves remain fixed upon the plant and will not be disturbed by any shaking. ”

“ The spore on germination gives rise to a small thalloid structure, the prothallium, on which the sexual organs are developed; this is the gametophyte or sexual generation. The sexual organs have the form of typical archegonia and antheridia. From the fertilised egg-cell there is developed the Pteridophyte plant or sporophyte, which bears the spores. This asexual generation shows a well-marked external differentiation into stem and leaves, and bears true roots. Internally the tissues exhibit a high degree of differentiation into distinct tissue-systems. ”

“ When we cut out a piece of a stem of Bryophyllum, and remove all the leaves, new shoots will be formed from the two apical buds of the stem, and roots will arise from the most basal nodes; provided that the stem is suspended in air saturated with water vapour. The growth in such a stem deprived of all leaves is slow. If we remove all the leaves on such a piece of stem except the two at the apical end, the stem will form only roots, but these will develop much more rapidly than on a stem without leaves. ”

“ The leaf-cells (Fig. 302) of the Sphagnum or bog-moss exhibit a curious departure from the ordinary type; they are large, polygonal, and elongated, and contain spiral fibres loosely coiled in their interior. The young leaf does not differ from the older; both are evolved by a gradual process of differentiation.
Fig. 302.—Section of leaf of Sphagnum moss, showing large cells of spiral fibres and connecting apertures.
Mosses, like liverworts, possess both antheridia and pistillida, which are engaged in the process of fructification. ”

“ Thus we see that if one or a few of the notches in a leaf of Bryophyllum grow out the other notches of the leaf are inhibited from growing. There is enough material present in the leaf for all the notches to grow into shoots as is proved by the fact that all will grow out if they are isolated from each other. This was explained on the assump­tion that the notches of a whole which happen to develop first, create a flow of these substances from the rest of the leaf to themselves and thus prevent any getting to the other notches. ”

“ Bryopsis plumosa, a most elegant little plant, flourishes in confinement; and Ulva latissima is probably the best of all sea-weeds for our purpose, and is one of the most easily procured on every shore.
The pieces of rock to which the plants are attached should be as clean as possible. All adhering sponges, in particular, should be carefully scraped off, unless they are wanted for immediate examination; as they are sure to die, and corrupt the soil and water with sulphuretted hydrogen, a most nauseous and noxious gas, which turns everything black with which it comes into contact. ”

“ On the other hand, fern-like seed-plants, known as Pteridosperms, and Gymnosperms belonging almost entirely to families now extinct, were abundant, while the Pteridophyta attained a development exceeding anything that they can now show. Among the lower classes of plants we have scarcely any knowledge of Palaeozoic Bryophyta; Fungi were probably abundant, but their remains give us little information; while, even among the Algae, which are better represented, well characterized specimens are scanty. ”

“ The cells grow smaller and more compact toward the outside of the section, until there are no spaces of any size between those of the outside or rind. The cells contain small chloroplasts like those of the higher plants, but owing to the presence of the brown pigment found in all of the class, in addition to the chlorophyll, they appear golden brown instead of green.
No non-sexual reproductive bodies are known in the rock weeds, beyond small branches that occur in clusters on the margins of the main branches, and probably become detached, forming new plants. ”

“ For propagation the bulbiferous portion is pegged down on the surface of a pot of suitable soil; if kept close in a moist atmosphere, the little buds will soon strike root and form independent plants. In Cystopteris the buds are deciduous, falling off as the fronds acquire maturity, but, if collected and pressed into the surface of a pot of soil and kept close, they will grow up into young plants the following season. In some genera of flowering plants, and notably in Bryophyllum, little plants form on various parts of the leaves. ”

“ When the leaves reach the surface, the shore wind, sweeping down from the hills, lifts them from the water, and they flutter in the air like mimic sails. Each leaf is a study. Many are encrusted with a delicate bryozoön, which presents the effect of white lace upon the surface, while a close inspection will reveal minute anemones, coiled tubular worms, which throw out flower-like organs of exquisite beauty; while flat shells lie among them, and crawling here and there are marvels of animal life, shell-less mollusks, which so mimic the weed that it is almost impossible to distinguish them. ”

“ From this superfluous pulp in unkindely, and wet years, may arise that multiplicity of little insects, which infest the Roots and Sprouts of tender Graines and pulses.
In the little nebbe or fructifying principle, the motion is regular, and not transvertible, as to make that ever the leaf, which nature intendeth the root; observable from their conversion, until they attain the right position, if seeds be set inversedly.
In vain we expect the production of plants from different parts of the seed, from the same corculum or little original proceed both germinations ”

“ Another species greatly resembles a branched sponge, and the third forms a velvety crust on the surface of rocks. Another genus, Vaucheria, is of a beautiful green colour, forming a velvety surface on moist soil, on mud-covered rocks overflowed by the tide, or parasitic on other sea-weeds. The most attractive plants of this family are however those of the genus Bryopsis, two of which are found on the British shores. The most common one is B. plumosa, the fronds of which grow usually in the shady and sheltered sides of rock pools. ”

“ The green spots and patches on the bark of old trees and fences, and sometimes even on damp earth, are due to enormous numbers of minute plants, green with the same green pigment as the leaves of the largest tree; while the green tint of the gray lichens on rocks and tree trunks is caused by similar single-celled plants which grow among the white fibers of the lichen proper. Besides these, there are many like plants which float about in fresh water, each a single cell. ”

“ In the modern world we divide all vegetation into two great series, that of the Flowering Plants (Phænogams) , which also produce true fruits and seeds, and that of the Flowerless Plants (Cryptogams) , which produce minute spores instead of seeds. The latter is in every respect the lower group. This lower series is again divisible into three classes—first and lowest, that of the Seaweeds, Moulds, and Lichens (Thallophytes) . Secondly, that of the Mosses and their allies (Anophytes) . Thirdly, that of the Ferns, Equisetums and Club-mosses (Acrogens) . ”

“ In the tropics it marks not only the shore plants and the vegetation of the arid plains, but also the epiphytes, which live upon the dry bark of the trees. European species are represented in this growth by the portulaccas. Among the plants is one, Bryophyllum calycinum, which has long been known to gardeners and botanists by the faculty which its leaves possess, when broken off and laid upon the ground, of developing buds on their edges, which finally become independent plants. ”

“ In a general sense we may regard the Bryophyta as derived from an algal ancestry, without being able to suggest the nature of the ancestral forms or the geological period at which they arose. Recent researches on those Algae such as Coleochaete which appeared to afford a close comparison in their alternation of generations with Riccia, have shown that the body resulting from the segmentation of the fertilized ovum is not so strictly comparable in the two cases as had been supposed. ”

“ Many species spread by means of a creeping much-branched rootstock, or as in house-leek, by runners which perish after producing a terminal leaf-rosette. In other cases small portions of the stem or leaves give rise to new plants by budding, as in Bryophyllum, where buds develop at the edges of the leaf and form new plants. ”

“ Separate pieces of the leaves of many plants, as of the begonia, produce buds from which the whole plant may grow out.
An aptitude for reproduction like that in plants exists in many cœlenterates, worms, and tunicates. The polyps of hydroids and of bryozoa, the stolons of an ascidian (Clavellina lepadiformis) , may give rise to buds in many places, and these grow up into the perfect hydroid, bryozoon, or ascidian. ”