The base of the nucellus is indicated by the chalaza ch, while the apex is at the micropyle m.
The vessels of the cord are prolonged to the base of the nucellus n by means of the raphe r.
The hilum or base of the seed, and the chalaza or base of the nucellusare united by means of the raphe r.
As the endosperm increases in size along with the embryo-sac and the embryo, the substance of the original nucellus of the ovule is gradually absorbed.
The remainder of the nucellus and the integuments of the ovules form the seed-coats.
Griffith recognised the development of the embryo-sac in the nucellus of the ovule which he took to be naked, missing the very slightly indicated integument.
Further he followed the germination of the pollen grains, not merely recording the fact that the tubes penetrated the nucellus all around the pollen chamber, but ascertaining in how many days the tubes were put forth.
The ovule is usually surrounded by one integument, which projects beyond the tip of the nucellus as a wide-open lobed funnel, which at the time of pollination folds inwards, and so assists in bringing the pollen-grains on to the nucellus.
In Araucaria and Saxegothaea the nucellus itself projects beyond the open micropyle and receives the pollen-grains direct.
A young ovule consists of a conical nucellus surrounded by a single integument terminating as a two-lipped micropyle.
Abies), on each side of which is situated an inverted ovule, consisting of a nucellus surrounded by a single integument.
Each ovule is enclosed at the base by an envelope or collar homologous with the lamina of a leaf; the fleshy and hard coats of the nucellus constitute a single integument.
A pollen-grain when first formed from its mother-cell consists of a single cell; in this condition it may be carried to the nucellus of the ovule (e.
A papery remnant of nucellus lines the inner face of the woody shell, and, as in cycadean seeds, the apical portion is readily separated as a cap covering the summit of the endosperm.
An ovule consists of a conical nucellus surrounded by a single integument.
The integument of the sterile ovule is prolonged above the nucellus as a spirally-twisted tube expanded at its apex into a flat stigma-like organ.
Meanwhile the tissue in the apical region of the nucellus has been undergoing disorganization, which results in the formation of a pollen-chamber (fig.
A complete female flower consists of a nucellus (fig.
There is a complex coat, C, which stands round the nucellus but is not joined to it, leaving the space l between them.
The whole organization is simpler than in the fossil Lagenostoma, but the coat is fused to the nucellus further up (see l).
Seed" Very similarly organized to the above, but the coat is joined to the nucellusabout two-thirds of its extent, and up to the level l.
In Coelebogyne (Euphorbiaceae) and in Funkia (Liliaceae) polyembryony results from an adventitious production of embryos from the cells of the nucellus around the top of the embryo-sac.
The Insemineae include forms in which the nucellus is not developed, and therefore there can be no seed.
In some cases the embryo or the embryo-sac sends out suckers into the nucellus and ovular integument.
The plants included are, however, mainly well-established parasites, and the absence of nucellus is only one of those characters of reduction to which parasites are liable.
The nucellus is a cellular tissue enveloping one large cell, the embryo-sac or macrospore.
The connexion between the base of the ovule and the base of the nucellus is kept up by means of the raphe r.
In Gymnosperms it usually remains deep in the nucellusand surrounded by a thick mass of cellular tissue (fig.
The point where the integuments are united to the base of the nucellus is called the chalaza (figs.
In gymnosperms the pollen-grain resting on the apex of the nucellus sends out its pollen-tubes, which at once penetrate the nucellus (fig.
A single cell of the nucellus enlarges greatly to form the embryo-sac or megaspore (fig.
This nucellus may remain naked, and alone form the ovule, as in some orders of parasitic plants such as Balanophoraceae, Santalaceae, &c.
Vertical section of the ovule of the Austrian Pine (Pinus austriaca), showing the nucellus a, consisting of delicate cellular tissue containing deep in its substance an embryo-sac b.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "nucellus" in a variety of sentences. We hope that you will now be able to make sentences using this word.
