Palaeobotany

“ It needs but a slight acquaintance with Geology for a Botanist to estimate the value of the most important applications of Palaeobotany; on the other hand, the bearing of fossil plants on the problems of phylogeny andvi descent cannot be adequately understood without a fairly intimate knowledge of recent Botany.
The student of elementary geology is not as a rule required to concern himself with vegetable palaeontology, beyond a general acquaintance with such facts as are to be found in geological text-books. ”

“ Here, as in any first-class garden of the tropics, much is very new and strange to the botanist from temperate climes. Palms, screwpines, giant bamboos, orchids and tree ferns, which he has known hitherto only from books or from the puny specimens of the plant house, become the commonplaces of every-day life. The sight of trees of the Composite family, Verbena family and many other groups represented at home only by herbs opens the eyes to some of the real wonders of tropical plant life. ”

“ That which chiefly distinguished the Palæozoic from the Secondary and Tertiary periods was its gorgeous flora. It was emphatically the period of plants,—"of herbs yielding seed after their kind." In no other age did the world ever witness such a flora: the youth of the earth was peculiarly a green and umbrageous youth,—a youth of dusk and tangled forests, of huge pines and stately araucarians, of the reed-like calamite, the tall tree-fern, the sculptured sigillaria, and the hirsute lepidodendron. ”

“ It may be premised that the modes of determination in fossil botany are necessarily different from those employed in recent botany. The palæobotanist must have recourse to characters derived from the leaves, the scars left by their fall, and the internal structures of the stem. These parts, held in little esteem by botanists in describing modern plants, and much neglected by them, must hold the first place in the regard of the fossil botanist, whereas the fructification, seldom preserved, and generally obscure, is of comparatively little service. ”

“ While always on the alert for rational explanations of obscure phenomena by means of the analogy supplied by existing causes, and ready to draw from a wide knowledge of recent botany, in the interpretation of problems furnished by fossil plants, the palaeobotanist must be constantly alive to the necessity for cautious statement. That there is the greatest need of moderation and safe reasoning in dealing with the botanical problems of past ages, will be apparent to anyone possessing but a superficial acquaintance with fossil plant literature. ”

“ Naturally the plates in the Vegetable System are of uneven quality, some are very good and not only are pleasing from the artistic point of view, but also give a concrete idea of the plants represented. It is impossible here to criticize this work in detail; but some idea of its scope may be given. The first volume and part of the second is concerned with the history of Botany; the origin of Systematic Botany; the Systems of Caesalpinus, Morison, Ray, Tournefort, Boerhaave, Linnaeus, and others; morphology, anatomy, physiology; and the effect of heat, light, air, soil and water on vegetation. ”

“ From many parts of the world large collections of fossil plants have been obtained from strata referred to the Rhaetic period, or to the upper division of the Triassic system. A comparison of floras from these geological horizons in different parts of the world points to a vegetation extending from Australia, Cape Colony, and South America, to Tonkin, the south of Sweden and North America, which was characterised by a greater uniformity than is shown by widely separated floras at the present day. ”

“ Among the principal forms of vegetation there are, indeed, some which constitute entire families, according to the so-called “natural system” of botanists. Bananas and Palms, Casuarineæ and Coniferæ, form distinct species in this mode of arrangement. The systematising botanist, however, separates into different groups many plants which the student of the physiognomy of nature is compelled to associate together. Where vegetable forms occur in large masses, the outlines and distribution of the leaves, and the form of the stems and branches lose their individuality and become blended together. ”

“ The modern flora of the earth admits of a grand twofold division into the Phænogamous, or flowering and seed-bearing plants, and the Cryptogamous, or flowerless and spore-bearing plants. In the former series, we have, first, those higher plants which start in life with two seed-leaves, and have stems with distinct bark, wood, and pith—the Exogens; secondly, those similar plants which begin life with one seed-leaf only, and have no distinction of bark, wood, and pith, in the stem—the Endogens ”

“ In these the axis remains short, nearly as it is in the bud; the leaves therefore remain close together in sets or circles; the outer ones, those of the calyx, generally partake more or less of the character of foliage; the next set are more delicate, and form the corolla, while the rest, the stamens and pistils, appear under forms very different from those of ordinary leaves, and are concerned in the production of seed. This view gives to Botany an interest which one who merely notices the shape and counts the parts of blossoms, without understanding their plan, has no conception of. ”

“ In the flora of the secondary eras, all botanists agree that palms existed, although in Europe plants of the family of zamia and cycas together with coniferæ predominated, and must have given a peculiar aspect to the flora. As only 200 or 300 species of plants are known in all the rocks ranging from the Trias to the Oolite inclusive, our data are too scanty as yet to affirm whether the vegetation of this second epoch was or was not on the whole of a simpler organization than that of our own times. ”

“ The plants of this subdivision of the vegetable kingdom, from their singular structure and mode of growth, their simple cylindrical stems, and coronets of pinnated foliage, resembling that of certain palms, their usually gyrate vernation like that of the ferns, and their anomalous inflorescence and fructification, are objects of great interest to the scientific botanist; while the abundance of their fossil remains in the secondary formations renders them of the highest importance to the geologist. ”

“ They consist of blue clays with some subordinate layers of lignite, and exhibit a richer flora than the overlying Newer Pliocene beds, and one receding farther from the existing vegetation of Europe. They also comprise more species common to the antecedent Miocene period. Among the genera of flowering plants, M. Gaudin enumerates pine, oak, evergreen oak, plum, plane, alder, elm, fig, laurel, maple, walnut, birch, buckthorn, hickory, sumach, sarsaparilla, sassafras, cinnamon, Glyptostrobus, Taxodium, Sequoia, Persea, Oreodaphne (Fig. 134) , Cassia, and Psoralea, and some others. ”

“ Supposing, nevertheless, that, in the main, the ascertained vegetation of the coal system is that which grew at the time of its formation, it is interesting to find that the terrestrial botany of our globe begins with classes of comparatively simple forms and structure. In the ranks of the vegetable kingdom, the lowest place is taken by plants of cellular tissue, and which have no flowers, (cryptogamia,) as lichens, mosses, fungi, ferns, sea-weeds. ”

“ American Character of the Flora.—If we consider not merely the number of species but those plants which constitute the mass of the Lower Miocene vegetation, we find the European part of the fossil flora very much less prominent than in the Œningen beds, while the foreground is occupied by American forms, by evergreen oaks, maples, poplars, planes, Liquidambar, Robinia, Sequoia, Taxodium, and ternate-leaved pines. ”

“ We do not aspire to a treatise on botany, but stop to consider only certain facts which are essential to this argument; a consideration of the higher plants will serve our purpose. Certain phytons are modified to become roots, which are the organs devoted to the absorption from the earth of the materials which are to be woven into the plant; other phytons become the stem for support; others the branches for expansion; others the leaves for respiration; others pistils and stamens for reproduction, while others become floral envelopes for their protection. ”

“ For our present purpose it is, however, enough to know that the members of the sub-Kingdom of the Angiosperms, or Flowering Plants, are not only the most recent in point of evolution, but the most numerous in the vegetable world of to-day. They embrace an endless variety of species widely different, in form, size and structural complexity. They exist under all the conditions of life, from the dense jungle of the Tropics to the home of eternal snows. In the ordinary walks of life we meet them everywhere, dominating our woodlands, prairies, meadows and ponds. ”

“ In so brief a treatment as that which is now employed, it is impossible to more than touch upon some of the salient features in the relations of paleobotany to the course of phylogeny, but it is, nevertheless, worth while to give special emphasis to the now well-recognized fact that a thorough knowledge of the interior structure of the plant, and especially of the stem, leads to a more comprehensive and exact acquaintance with relationships than that of any other part. ”

“ Since the greater refinements and thoroughness of scientific methods and the enormous and ever-increasing mass of literature have inevitably led to extreme specialisation, it is more than ever important to look beyond the immediate limits of one’s own subject, and to note its points of contact with other lines of research. A palaeobotanist is primarily concerned with the determination and description of fossil plants, but he must at the same time constantly keep in view the bearing of his work on wider questions of botanical or geological importance. ”

“ The double flowers, so much admired by the florists, are termed by the botanist vegetable monsters; in some of these the petals are multiplied three or four times, but without excluding the stamens, hence they produce some seeds, as Campanula and Stramoneum; but in others the petals become so numerous as totally to exclude the stamens, or males; as Caltha, Peonia, and Alcea; these produce no seeds, and are termed eunuchs. Philos. Botan. No. 150.
These vegetable monsters are formed in many ways. 1st. By the multiplication of the petals and the exclusion of the nectaries, as in larkspur. ”

“ The trend of the evolution of the plant kingdom has been in the direction of the establishment of a vegetation of fixed habit and adapted to the vicissitudes of a life on land, and the Angiosperms are the highest expression of this evolution and constitute the dominant vegetation of the earth’s surface at the present epoch. There is no land-area from the poles to the equator, where plant-life is possible, upon which Angiosperms are not found. ”

“ This plant is the first that vegetates on naked rocks, covering them with a kind of tapestry, and draws its nourishment perhaps chiefly from the air; after it perishes, earth enough is left for other mosses to root themselves; and after some ages a soil is produced sufficient for the growth of more succulent and large vegetables. In this manner perhaps the whole earth has been gradually covered with vegetation, after it was raised out of the primeval ocean by subterraneous fires. ”

“ The earliest type of vegetation was that which we now find in hot springs, continued with the alga? found in cool or cold waters, all of which possessed a delicacy of structure which permitted speedy decay. The great abundance of such organisms probably afford an adequate explanation of the Laurentian and later forms of graphite which is regarded by many as the remains of former vegetation. While this hypothesis may be accepted provisionally, paleobotany is nevertheless wholly unable to furnish any clue to the life history of the individuals, or even to inform us as to the specific types. ”

“ The Grasses, Umbelliferous plants, Mosses, Sea-weeds, Ferns, Liliaceous plants, Orchises, Compound flowers, each constitute a family strikingly similar in form and qualities among themselves, and no less evidently distinct from all others. If the whole vegetable kingdom could with equal facility be distributed into tribes or classes, the study of Botany on such a plan would be no less easy than satisfactory. ”

“ It contains a complete, although concise, sketch of Structural Botany and Vegetable Physiology, and a birds'-eye view of the whole vegetable kingdom in its subdivision into families, illustrated by over thirteen hundred engravings on wood. It has become a standard of botany, wherever our language is read. ”

“ As the known species of living vegetables are more than fifty thousand, and the study of fossil botany is as yet but in its infancy, it is probable that a large amount of fossil species lies hid in the bowels of the earth, which the discoveries of each passing year will he continually bringing to light.
The plants of the First period are in a great measure. composed of Ferns, and gigantic Equisetaceæ; and of families, of intermediate character between existing forms of Lycopodiaceæ and Coniferæ, e. g. ”

“ The botanical evidences which geologists too often accept as proofs of specific identity are such as no botanist would attach any importance to in the investigation of existing plants. The faintest traces assumed to be of vegetable origin are habitually made into genera and species by naturalists ignorant of the structure, affinities and distribution of living plants, and of such materials the bulk of so-called systems of fossil plants is composed. ”