Phanerogams Sentence Examples
This is the case in the stems of must Phanerogams and of some Pteridophytes.
When the protoxylems have an intermediate position the stele is inesarch (many Pteridophytes and some of the more primitive Phanerogams).
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.
The least satisfactory part of all these systems was that concerned with the lower plants or Cryptogams as contrasted with the higher or flowering plants (Phanerogams).
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.Advertisement
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.
If the axis of such a sporogonium were prolonged downwards into the soil to form a fixing and absorptive root, the whole structure would become a physiologically independent plant, exhibiting in many though by no means all respects the leading features of the sporophyte or ordinary vegetative and spore-bearing individual in Ptericlophytes and Phanerogams. These facts, among others, have led to the theory, plausible in some respects, of the origin of this sporophyte by descent from an Anthoceros-like sporogonium (see PTERIDOPHYTA).
Within the limits of the sporophyte generation the Pteridophytes and Phanerogams also differ from the Bryophytes in possessing special assimilative and transpiring organs, the leaves, though these organs are developed, as we have seen, in the gametophyte of many liverworts and of all the mosses.
In most of the Phanerogams the apical (or primary) merislem, instead of consisting of a single apical cell or a group of initials, is stratifiedi.e.
Many other cases of symbiosis have been investigated with some completeness, especially those in which lower plants than the Phanerogams are concerned.Advertisement
Goebel (Organograp/zy) gives several instances of the conversion of the root into a shoot in ferns, and a few in phanerogams (Lislera ovata, Neottia nidusavis, Anthurium longifolium).
A system of classification for the Phanerogams, or, as they are frequently now called, Spermatophyta (seed-plants), which has been much used in Great Britain and in America, is that of Bentham and Hooker, whose Genera Plantarum (1862-1883) is a descriptive account of all the genera of flowering plants, based on their careful examination.
In general structure they approach the Phanerogams with which they form collectively the Vascular Plants as contrasted with the Cellular PlantsThallophyta and Bryophyta.
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.
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.Advertisement
Only 275 to 280 phanerogams are found within this region.
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.
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.
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.
The phanerogams number 570, apportioned to 314 genera, and of these over 220 species and 98 genera are unknown elsewhere.Advertisement
At present 435 species of phanerogams and vascular cryptogams are known; the lower orders have been little investigated.
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.
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.
Associated with it are other tissues, consisting of parenchyma, mainly starchy, and in the Phanerogams particularly, of special stereom.
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.Advertisement
It must be remembered that phanerogams also include parasitic speciese.g.
In the seed-forming plants (Phanerogams) one or more primary leaves (cotyledons) are already formed in the resting embryo.