This is the case in the stems of must Phanerogams and of some Pteridophytes.
De Bary's Comparative Anatomy of the Phanerogams and Ferns (1877) supplied an admirable presentation of the facts so far known.
Phanerogams or IV.
Ferns, horse-tails, club mosses, &c., and Phanerogams or Flowering Plants) the main plant-body, that which we speak of in ordinary language as the plant, is called the sporophyte because it bears the asexual reproductive cells or spores.
A considerable evolution in complexity can be traced in passing from the simplest forms of xylem and phloem found in the primary vascular tissues both among Pteridophytes and Phanerogams to these highly differentiated types.
Moreover there is the fact that the flowers of nearly all the primitive phanerogams, such as the Gymnosperms, consist solely of sporophylls, having no perianth.
Only 275 to 280 phanerogams are found within this region.
Leguminosae, the two most numerous orders of phanerogams, but in number of individual plants it probably far exceeds either; whilst from the wide extension of many of its species, the proportion of Gramineae to other orders in the various floras of the world is much higher than its number of species would lead one to expect.
The Gymnosperms, with the Angiosperms, constitute the existing groups of seed-bearing plants or Phanerogams: the importance of the seed as a distinguishing feature in the plant kingdom may be emphasized by the use of the designation Spermophyta for these two groups, in contrast to the Pteridophyta and Bryophyta in which true seeds are unknown.
The flower is a characteristic feature of the highest group of the plant kingdom - the flowering plants (Phanerogams) - and is the name given to the association of organs, more or less leaf-like in form, which are concerned with the production of the fruit or seed.
In general structure they approach the Phanerogams with which they form collectively the Vascular Plants as contrasted with the Cellular PlantsThallophyta and Bryophyta.
I&Vertical section of a Palm-stem showing the root as it is found in most Pteridophytes vascular bundle,, Jr. curving and many Phanerogams has been already inwards and then outwards.
Place, it appears so if the space occupied by Russia be taken into account, only 3300 species of phanerogams and ferns 2 Bibliography of Meteorology: Memoirs of the Central Physical Observatory; Repertorium fiir Meteorologie and Meteorological Sbornik, published by the same body; Veselovsky, Climate of Russia (Russian); H.
Such aberrant forms are to be regarded in the same light as Cuscuta and Orobanchaceae, for example, among Phanerogams. As these non-green plants do not cease to be classed with other Phanerogams, so must the forms in question be retained among algae.
The phanerogams number 570, apportioned to 314 genera, and of these over 220 species and 98 genera are unknown elsewhere.
Of Phanerogams, only the Dryas octopetala covers small areas of the debris, interspersed with isolated Cochlearia, &c., and, where a layer of thinner clay has been deposited in sheltered places, the surface is covered with saxifrages, &c.; and a carpet of mosses allows the arctic willow (Salix polaris) to develop. Where a thin sheet of humus, fertilized by lemmings, has accumulated, a few flowering plants appear, but even so their brilliant flowers spring direct from the soil, concealing the developed leaflets, while their horizontally spread roots grow out of proportion; only the Salix lanata rises to 7 or 8 in., sending out roots I in.
The plant world falls into two great divisions, the higher or flowering plants (Phanerogams), characterized by the formation of a seed, and the lower or flowerless plants (Cryptogams), in which no seed is formed but the plants are disseminated by means of unicellular bodies termed spores.
A layer of cork is regularly formed in most Phanerogams across the base of the petiole before leaf fall, so as to cover the wound caused by the separation of the leaf from the stem.
Trans., Comparative A-natomy of the Vegetative Organs of the Phanerogams and Ferns, Oxford, 1882).
It must be remembered that phanerogams also include parasitic speciese.g.
In the vascular cryptogams and phanerogams it takes place in the spore mother cells and the reduced number is found in all the cells of the gametophyte, the full number in those of the sporophyte.
At present 435 species of phanerogams and vascular cryptogams are known; the lower orders have been little investigated.
These two great divisions are moreover of unequal value, for the Cryptogams comprise several groups differing from each other by characters as marked as those which separate some of them from the Phanerogams. The following groups or sub-kingdoms are those which are now generally recognized:
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.
One of the most striking characters common to the two highest groups of plants, the Pteridophytes and Phanerogams, is the Vascular possession of a double (hydrom-leptom) conducting .s system, such as we saw among the highest mosses, YS em.
Associated with it are other tissues, consisting of parenchyma, mainly starchy, and in the Phanerogams particularly, of special stereom.
This is a morphological term given to the particular~ type of hydrom found in both Pteridophytes and Phanerogams, together with the parenchyma or stereom, or both, included within the boundaries of the hydrom tissue strand.
The leptom found in Pteridophytes and Phanerogams with its associated cells, and is entirely parallel with the xylem.
In the seed-forming plants (Phanerogams) one or more primary leaves (cotyledons) are already formed in the resting embryo.