The excitation which the light effects in the cotyledon must be transmitted to the hypocotyl and curvature takes place only from such a transmitted excitation.
If the cotyledon be shaded and the light be permitted to fall on one side of the hypocotyl, no heliotropic curving takes place.
Effect of unilateral light on hyponastic movement of thecotyledon of Pepo.
In this seedling the tapering sheathing leaf or cotyledon is about 5 mm.
Hence we may conclude that it is only thecotyledon that is sensitive to the light stimulus, and it is only the hypocotyl which can carry out the movement.
The curvature makes itself apparent only if the cotyledon be illuminated from one side whether the hypocotyl be exposed to light or not.
Figure 189 exhibits the effect of light applied alternately above or below the cotyledon of Cucurbita Pepo.
In the Paniceae, the local unilateral stimulation of the tip of the cotyledon induces positive curvature in the growing hypocotyl, at some distance from the tip.
On account of the more rapid growth of the lower side, the cotyledon was exhibiting a hyponastic up-movement.
In those plants in which there is only a single cotyledon in the embryo, hence called monocotyledonous, the embryo usually has a cylindrical form more or less rounded at the extremities, or elongated and fusiform, often oblique.
The germination of a Monocotyledonous plant, with the cotyledon remaining in the ground, is shown at c.
They may also be said to have no seeds, for the spores, or sporules as they are called, are very different from the seeds of vascular plants, and they have neither cotyledon nor embryo.
A grain cut through the middle in the opposite direction, dividing the embryo through its thick cotyledon and its plumule, the latter consisting of two leaves, one enclosing the other.
Mirabilis, there is a singular modification; onecotyledon is almost wanting, being reduced to a rudiment, leaving it for the other to do the work.
There, in the seed, the cotyledon remains, imbibing nourishment from the softened albumen, and transmitting it to the growing root below and new-forming leaves above.
A germinating seedling of the same, its plumule developed into the first four leaves (alternate), the first one rudimentary, the cotyledon remains in the seed.
Germinating Onion, more advanced, the chink at base of cotyledon opening for the protrusion of the plumule, consisting of a thread-shaped leaf.
It would appear therefore that thecotyledon answers to a minute leaf rolled up, and that a chink through which the plumule grows out is a part of the inrolled edges.
Setaria prevents the plant curving towards the light, and here there is no question of removing the sense-organ since the greater part of the sensitive cotyledon is intact.
By using Piccard's method I have succeeded in showing that the gravitational sensitiveness of the cotyledon of Sorghum is certainly much greater than the sensitiveness of the hypocotyl--if indeed any such sensitiveness exists.
I sought to prove that the cotyledon of Setaria is not only the organ for light-perception, but also for gravitation.
On this view the monocotyledons must be assumed to have lost the cambium and all its influence on secondary growth, the differentiation of the flower into calyx and corolla, the second cotyledonor seed-leaf and several other characters.
When the grain has begun to grow, examination shows that the starch grains near the edge of the cotyledon are much smaller and quite irregular, having large holes in them.
A later stage shows the hypocotyl lifting the cotyledon upward.
Illustration: Three views of a kidney bean, the lower one having one cotyledon removed to show the hypocotyl and plumule.
The enzyme found in the cotyledon of the corn, which changes starch to grape sugar, is called diastase.
A test of the cotyledon of a bean for protein food with nitric acid and ammonium hydrate shows us the presence of this food.
Another nutrient present in the beancotyledon is protein.
They will be found to give a reaction showing the presence of sugar along the edge of the cotyledon and between it and the endosperm.
Careful inspection shows the hypocotyl and plumule (the latter pointing toward the free end of the grain) and a part surrounding them, the single cotyledon (see Figure).
If we mash up a little piece of a bean cotyledon which has been previously soaked in water, and test for starch with iodine solution, the characteristic blue-black color appears, showing the presence of the starch.
We find that the one cotyledon of the corn grain does not serve the same purpose to the young plant as do the two cotyledons of the bean.
The corn pushed a slender growing point to the surface leaving the cotyledon and endosperm behind in the soil but still attached to the little plant (Fig.
Within the cotyledon will be found a little growing shoot pointed toward the top of the kernel.
Bean with one cotyledon removed, after sprouting had begun.
Notice the curved hypocotyls pulling the seed-leaves or cotyledon out of the soil.
I have looked at your desert garden so much I would know a Cotyledon if I saw it.
California is full of girls; but this is the finest Cotyledon of this family I have ever seen.
That first day, as soon as I put down the Cotyledon safely and tucked in my blouse, I would have put my hand in yours and started around the world, if you had asked me to.
I fervently hoped not to break more than a dozen of my legs and arms, and was forced to bring down intact the finest Cotyledon pulverulenta that Daddy or I had found in fourteen years of collecting in California.
The instant I deposited my Cotyledon in a safe place I would have put my hand in Peter Morrison's and started around the world if he had asked me to go.
You have made me feel that I would be about twice the man I am if I had spent the time I have wasted in plain jazzing around, hunting Cotyledon or trap-door spiders' nests.
Embryo with a single cotyledon and the early leaves always alternate.
Embryo short and thick (proper cotyledon almost obsolete), with an open chink or cleft its whole length, from which protrudes a doubly curved slender plumule.
In the genus Opuntia, the cotyledonstage (see Fig.
This begins as soon as the cotyledon has reached the light, and thus the formation of fibres of woody matter takes place, which fibres descend from the cotyledonto the radicle.
They have but one cotyledon in the seed and have no bark, but in place thereof a kind of natural varnish or thin coating of silica; this varnish or external polish is seen in the stalks of corn and on canes.
Of or pertaining to a cotyledon or cotyledons; having a seed lobe.
Out of this the thick stem has issued; and we find that it is only the cotyledon of the seed, that has prolonged its base in the process of germination, in order to throw up, clear of the nut, the plumule and radicle.
From b, c, d, e, the front cotyledon has been cut away, to show the progress of the plumule.
The same bean, with one cotyledon removed, to show the plumule.
In some Monocotyledons, however, thecotyledon is not really terminal.
In South Africa a disorder known as nenta appears in goats after eating certain plants, especially Cotyledon ventricosa.
A portion of the uterus (A) is shown with the maternal cotyledon (BB) attached to it.
Our last selection from this order is the Wall Pennywort or Navelwort (Cotyledon umbilicus)--a peculiar plant, common on rocks and walls in the South and West of England.
Those plants whose seeds have only one cotyledon may be known by the absence of a central pith and true bark in the stem, while the wood is arranged in scattered bundles instead of in a ring or rings.
In Wheat and Oats the cotyledon can be easily seen in the largest seedlings by pulling off the dry husk of the grain.
If the term cotyledon be given them first for those of the Bean and Pea they will say when they come to the Morning-Glory, "but those are leaves, not cotyledons.
The so-called “cloud band” and the cotyledon symbol (representing the life idea) may be seen in many fine Persian rugs.
Immediately before this latter fall the same cotyledon had risen from a vertically downward to a vertically upward position in 1 h.
He states that good figures of thecotyledon of the onion have been given by Tittmann and by Sachs in his 'Experimental Physiologie,' p.
Cotyledon umbilicus: circumnutation and downward movement of another stolon, traced on vertical glass, from 9.
This was conspicuous with those of Oxalis sensitiva, in which one cotyledon might be seen during the daytime rising up until it stood vertically, whilst the opposite one was sinking down.
In one of these cases, the apex of the cotyledon crossed five of the divisions of the micrometer (i.
Cyclamen does not produce any distinct stem, and only a single cotyledon appears at first;* its petiole * This is the conclusion arrived at by Dr.
The leftcotyledon (Lc) is likewise raised, but it is also twisted so that its blade, instead of exactly facing the opposite one, now stands at nearly right angles to it.
In these two cases perhaps the pulvinus was accidentally pricked, for on pricking the pulvinus of another cotyledon it rose a little.
In the case of monocotyledons the plumule or cotyledon is rarely arched, as far as we have seen; but this is the case with the leaf-like cotyledon of the onion; and the crown of the arch is here strengthened by a special protuberance.
In the Gramineae the summit of the straight, sheath-like cotyledon is developed into a hard sharp crest, which evidently serves for breaking through the earth.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "cotyledon" in a variety of sentences. We hope that you will now be able to make sentences using this word. Other words: blade; bract; flag; frond; leaf; leaflet; needle; petal; pile; spear; spire
