nucellus's Usage Examples:

The point where the integuments are united to the base of the nucellus is called the chalaza (figs.

- Campylotropous ovule of wall-flower (Cheiranthus), showing the funicle f, which attaches the ovule to the placenta; p, the outer, s, the inner coat, n, the nucellus, ch, the chalaza.

A young ovule consists of a conical nucellus surrounded by a single integument terminating as a two-lipped micropyle.

The megaspore of Welwitschia is filled with a prothallus-tissue before fertilization, and some of the prothallus-cells function as egg-cells; these grow upwards as long tubes into the apical region of the nucellus, where they come into contact with the pollen-tubes.

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.

dandelion clock and blown away the seeds while making a wish?- Anatropous ovule of Dandelion (Taraxacum), nucellus, which is inverted, so that the chalaza ch, is removed from the base or hilum h, while the micropyle f is near the base.

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 the ripe seed the integument assumes the form of a fleshy envelope, succeeded internally by a hard woody shell, internal to which is a thin papery membrane - the apical portion of the nucellus - which is easily dissected out as a conical cap covering the apex of the endosperm.

This is a large seed, with a very long micropyle; it has a beaked pollen-chamber, and a complex integument made up of hard and fleshy layers, closely resembling the seed of a modern Cycad; the nucellus, however, was free from the integument, each a sketch after Kidston.

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.

coats surrounding the central nucellus, except at the apex where an opening, the micropyle, is left.

In some plants the nucellus is not thus absorbed, but itself becomes a seat of deposit of reserve-food constituting the perisperm which may coexist with endosperm, as in the water-lily order, or may alone form a food-reserve for the embryo, as in Canna.

Synonyms:

plant structure, plant part, ovule,

Antonyms:

artifact,