Search results
Results from the WOW.Com Content Network
Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.
Guard cell – one of the paired epidermal cells that control the opening and closing of a stoma in plant tissue. Heartwood – the older, nonliving central wood of a tree or woody plant, usually darker and harder than the younger sapwood. Also called duramen. Herbaceous – non-woody and dying to the ground at the end of the growing season.
The anatomy of the tepals and petals is similar to that of the sepals. The epidermal cell walls are often convex or papillose, especially on the adaxial side. In many petals, such as those of Brassica napus, the papillae are conical, with a marked cuticular thickening at the apex, and radial striations toward the base. It has been suggested ...
Pollen tube elongation is an integral stage in the plant life cycle. The pollen tube acts as a conduit to transport the male gamete cells from the pollen grain—either from the stigma (in flowering plants) to the ovules at the base of the pistil or directly through ovule tissue in some gymnosperms.
At this point the end of the pollen tube bursts and releases the two sperm cells, one of which makes its way to an egg, while also losing its cell membrane and much of its protoplasm. The sperm's nucleus then fuses with the egg's nucleus, resulting in the formation of a zygote, a diploid (two copies of each chromosome) cell. [2] [92]
These cells are surrounded by a wall of sterile cells called the tapetum, which supplies food to the cell and eventually becomes the cell wall for the pollen grain. These sets of sporogenous cells eventually develop into diploid microspore mother cells. These microspore mother cells, also called microsporocytes, then undergo meiosis and become ...
In Lauraceae, for example, the pollen sacs are spaced apart and open independently. The tissue between the locules and the cells is called the connective and the parenchyma. Both pollen sacs are separated by the stomium. When the anther is dehiscing, it opens at the stomium. The outer cells of the theca form the epidermis.
Stamen is the Latin word meaning "thread" (originally thread of the warp, in weaving). [8]Filament derives from classical Latin filum, meaning "thread" [8]; Anther derives from French anthère, [9] from classical Latin anthera, meaning "medicine extracted from the flower" [10] [11] in turn from Ancient Greek ἀνθηρά (anthērá), [9] [11] feminine of ἀνθηρός (anthērós) meaning ...