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

VI. PLANT KINGDOM SYSTEM

LOWER SPORE PLANTS

GENERAL CHARACTERISTICS AND FEATURES

Order Chlorellales - Chlorellales

Unicellular and colonial green Algae of coccoid morphological body Structure.

Asexual reproduction occurs via autospores. The chloroplast is parietal, cup-shaped, containing a single pyrenoid.

These algae are widespread mainly in freshwater bodies, as well as in the edaphon and aerophyton. They are active components of algocenoses in standing-Water bodies and algae communities of aerophytic habitats, serving as indicators of the aquatic environment state. They cause water "blooming" in natural water bodies. Recognized objects of aquaculture and phycotechnology, with certain species introduced into industrial culture.

Genus Chlorella - Chlorella (Fig. 40). Unicellular, coccoid algae with a smooth Cell wall (containing sporopollenin), a parietal cup-shaped chloroplast, and a pyrenoid. Reproduction is exclusively by autospores (2-8), which are released after the rupture of the mother cell wall. Resting Cells, known as akinetes, have been described for certain species.

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Fig. 40. Various Selection/3.html">Stages of development of Chlorella vulgaris:

A - vegetative cell; B-C - formation and release of autospores from the

mother cell

An object of industrial culture and diverse scientific and practical experiments (space, physiological, biochemical, etc.), a component of algocenoses in various types of water bodies, the edaphon and aerophyton, as well as the phycological layer of Lichens and other symbiotic communities.

Genus Oocystis - Oocystis (Fig. 41). Unicellular or colonial green algae with oval cells featuring widely rounded poles and noticeable thickening at the ends. The walls of the mother cell are capable of significant expansion during reproduction, retaining multiple (up to 3) generations of daughter cells/colonies. Reproduction occurs via 2-16 autospores, which are released upon gelatinization or rupture of the mother cell wall.

Fig. 41. Vegetative cell and the pattern of first-generation colony formation

in the genus Oocystis

A common representative of the plankton and benthos in various types of water bodies, frequently found in standing waters.