These Exogenous trees are Gymnosperms, having woody tissue like that of Coniferæ.
Silicified stems of trees have been observed in various parts of the world, with their structure well preserved, so that their Endogenous and Exogenous character could be easily determined.
In such stems the woody bundles are more numerous and crowded toward the circumference, and so the harder wood is outside; while in an exogenous stem the oldest and hardest wood is toward the centre.
Heart-wood, the older or matured wood of exogenous trees, 142.
Diagram of a cross section of a very young exogenous stem, showing six woody bundles or wedges.
This is exogenous growth, or outside-growing, as the name denotes.
The wood of a Fern-trunk is very different, however, from that of a palm, or of any exogenous stem either.
The Wood= of an exogenous trunk, having the old growths covered by the new, remains nearly unchanged in age, except from decay.
Pith, the cellular centre of an exogenous stem, 138.
Let us note in this way, in the first place, the introduction of the familiar generic forms of exogenous trees.
In others, the ordinary exogenous trees predominate, almost to the exclusion of others.
For some species in some situations major environmental variables are paramount in regulating timing of breeding, but in others the innate, regulatory "clock" is less closely tied to conspicuous exogenous stimuli.
For the moment, however, we may consider exogenous controls only.
Any exogenous control, or environmental variable, can be looked on simply as a timing oscillator.
The rays of cellular tissue in a transverse section of an exogenous stem and extending from the pith to the bark.
The stem of an exogenous plant has been compared to a piece of linen, of which the weft is composed of cellular tissue, and the warp of fibrous and vascular tissue--crossing each other.
The mechanical properties of the stems of trees, both exogenous and endogenous, render them extremely serviceable to mankind.
There is a principle which, in trees of this character, namely, such as are of exogenous structure, will determine the age with very close accuracy.
Their growth is essentially endogenous, and will probably be found when examined aborigine to approximate to that of Cycadeae, although these last are of a more exogenous than endogenous nature.
And with respect to Sarcocoidalis I shall adopt the same opinion, if I find on enquiry that a binary number, and imperfection of the female as compared with the male, are more characteristic of Endogenous than of Exogenous growth.
Exogenous stems are those that grow by the addition of wood on their outer surface, underneath the bark.
A genus of exogenous polypetalous plants, embracing about one hundred and eighty species.
Exogenous trees are those the trunks of which are built up by rings or layers, each deposited consecutively upon the outside of the others.
Exogenous trees are divided into broad-leaved trees and needle-leaved conifers.
This may, however, be placed in connection with the appearance of an exogenous tree (Syringoxylon) in the Devonian, referred to in a previous chapter.
Some of the beds of coal are eight feet in thickness, and the shales associated with them abound in leaves of exogenous trees generally similar to those still living in America.
Pertaining to, or resembling, an order of plants like the palms, but having exogenous wood.
The soft spongy substance in the center of the stems of many plants and trees, especially those of the dicotyledonous or exogenous classes.
A genus of cycadaceous plants, having the appearance of low palms, but with exogenous wood.
Defn: Of or pertaining to a natural order (Sterculiaceæ) of polypetalous exogenous plants, mostly tropical.
Defn: The soft spongy substance in the center of the stems of many plants and trees, especially those of the dicotyledonous or exogenous classes.
Defn: A genus of exogenous polypetalous plants, embracing about one hundred and eighty species.
Defn: A genus of cycadaceous plants, having the appearance of low palms, but with exogenous wood.
The growth of the wood of exogenoustrees takes place thru the ability, already noted, of protoplasmic cells to divide.
Three Stages in the Development of an Exogenous Stem.
But they are present in all exogenous woods, and can readily be seen with the microscope.
The peculiar form known as the multilocular echinococcus is probably a mere variety of the exogenous type.
The so-called exogenous type occurs sparingly in man, whilst the endogenous type is very abundant.
The exogenous and endogenous hydatids may coexist in the same bearer.
Selecting any ordinary fresh example of the exogenous kind, and laying the tumour open with a scalpel, we notice in the first instance an escape of a clear transparent, amber-coloured fluid.
CX] This different development of the exogenous axis is accompanied with appropriate external appearances in the stems, and the changes which take place in their markings.
The plan is the same with that now seen in the stems of exogenous phænogams, and which has long ceased to be used in those of the Lycopods.
The development of this exogenous cylinder is different in amount and rate in different species.
The plant was not truly exogenous, and the appearance of rings is independent of the causes which determine the layers of growth in exogenous plants.
Thus, a stem was constructed having pith, wood, and bark, and capable of additions to the exterior of the woody wedges by a true exogenous growth.
Older stems have a second or outer layer of scalariform fibres in wedges with medullary rays, and strengthening the stem by a true exogenous growth, much as in the Diploxylon type of Sigiliaria.
In the case of exogenous woods, three sections are necessary to exhibit the whole of the structures.
It would seem that these, while having strong exogenous peculiarities, are really stems of tree-ferns, thus placing this family in the same position of advancement with the Lycopods and Equisetaceæ of the Coal period.
An entirely different kind of shrinkage-crack is that which occurs in certain carbonised and flattened plants, and which sometimes communicates to them a marvellous resemblance to the netted under surface of an exogenous leaf.
The stems are exogenous in structure, but with slender wood and thick bark, and barred tissue, or properly as tissue intermediate between this and the disc-bearing fibres of the pines.
In these trees the exogenous outer cylinder is less developed than in the Lepidodendra, and is sometimes wanting in stems or branches of some thickness.
Most of the trees with which we have to do are of the exogenous type.
The exogenoustree grows by adding to its exterior.
Any injury is felt most severely by the first class on the bark, by the second on the inside, while the inside of the exogenous may be removed, or the outside of the endogenous may be cut, without stopping the growth in the least.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "exogenous" in a variety of sentences. We hope that you will now be able to make sentences using this word.
