BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

VIII. BASICS OF PLANT MORPHOLOGY AND ANATOMY

Features of angiosperm reproduction

Development of endosperm and perisperm

Endosperm

A fully formed endosperm consists of large parenchymal Cells filled with various nutrients. Depending on the mode of development, Three types of endosperm are distinguished: nuclear, cellular, and helobial (basal).

The nuclear type of endosperm development is characterized by the delayed formation of Cell walls between dividing nuclei. Following nuclear division, cell plates do not form immediately, resulting in A large number of nuclei freely floating in the Cytoplasm. Cell walls develop at a later stage. The nuclear type of endosperm is typical of families such as Papaveraceae, Lauraceae, Rosaceae, Polygonaceae, and others.

The cellular type is characterized by The formation of cell walls after each nuclear division. This type of endosperm development is also common in many plants, notably Magnoliaceae, Lamiaceae, Campanulaceae, Asteraceae, and certain monocotyledons.

The basal (helobial) type of endosperm is characterized by the division of the central cell into two cells upon its First Division: a larger (micropylar) one and a smaller (chalazal) one. In the micropylar region of the endosperm, numerous free nuclei initially form, followed by the appearance of cell walls; the chalazal region forms either two cells or numerous free nuclei. The chalazal part does not contribute to the final Structure OF THE endosperm, functioning instead as a haustorium. This type of endosperm is typical of the majority of monocotyledonous plants.

Perisperm

During The Development of the embryo sac and subsequently the embryo, a portion of the nucellus wall tissue is retained. Filled with nutrients, it transforms into an external storage tissue known as the perisperm. Perisperm is characteristic of Piperaceae, Nymphaeaceae, and Caryophyllaceae.

In many plants, the seed contains an endosperm surrounded by a perisperm (e.g., black pepper). In this case, during seed germination, the endosperm extracts nutrients from the perisperm and transfers them to the growing embryo.