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If the pollen sacs are not adjacent, or if they open separately, then no thecae are formed. 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 ...
Diagram of an anther in cross section. 1: Filament; 2: Theca; 3: Connective (the conducting vessels in red); 4: Pollen sac (also called sporangium) The androecium is one of the fertile cycles of flowers. The parts that make up the androecium are called stamens whose function is the generation of male gametophytes or pollen grains.
Development of pollen sacs begins with the differentiation of archesporial cells in the hypodermal region below epidermis at four corners of the young anther. The archesporial cells divide by periclinal division to give a subepidermal primary parietal layer and a primary sporogenous layer. The cells of the primary parietal layer divide by ...
Trinucleate – pollen containing three nuclei when shed. Valvular – anthers opening through valves or small flaps; e.g. Berberis. Versatile – anthers pivoting freely on the filament. Pollen – Stamen – Anther – the distal end of the stamen where pollen is produced, normally composed of two parts called anther-sacs and pollen-sacs .
Bees in four tribes of the family Apidae, subfamily Apinae have corbiculae: the honey bees, bumblebees, stingless bees, and orchid bees. [14] [15] The corbicula is a polished cavity surrounded by a fringe of hairs, into which the bee collects the pollen; most other bees possess a structure called the scopa, which is similar in function, but is a dense mass of branched hairs into which pollen ...
Pollen is often enclosed in paired synangia (pollen sacs). The synangia lie on the adaxial (inner) edge of pollen-bearing leaf-like structures known as microsporophylls . This contrasts with cycads, all of which lack discrete synangia and bear pollen on the abaxial (outer) surface of their microsporophylls.
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.
Tapetum is important for the nutrition and development of pollen grains and a source of precursors for the pollen coat. [1] The cells are usually bigger and normally have more than one nucleus per cell. As the sporogenous cells undergo mitosis, the nuclei of tapetal cells also divide.