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

VI. PLANT SYSTEMATICS

LOWER SPORE PLANTS

GENERAL CHARACTERISTICS AND FEATURES

Order Bangiales - Bangiales

It unites Algae with filamentous and heterotrichous structures, featuring multiseriate unbranched or laminar thalli. Asexual reproduction occurs via monospores, occasionally polyspores, and auxiliary "shoots". A sexual process is known. The trichogyne is absent. Carpospores are naked. They inhabit the coastal littoral zone of northern and southern seas. Typical representatives include species of the genera Bangia and Porphyra.

The genus Porphyra - Porphyraceae (Fig. 15) is widespread in the coastal littoral and sublittoral zones of northern and southern seas, growing as an epilith on stones and rocks, or as an epiphytic Organism on the thalli of macroscopic marine algae.

Class="center">Water/water.files/image015.jpg" width="586"/>

Fig. 15. General microscopic Structure OF THE Porphyra thallus:

A - general appearance; B - cross-section of the thallus with spermatangia; C - cross-section of the thallus with carpogonia, whose contents divide after Fertilization to form carpospores; D - Conchocelis stage

It is characterized by a pink, leaf-like laminar thallus with smooth or wavy margins, reaching up to 50 cm in length (occasionally up to 2 m) and 10-20 cm in width. The thallus is unistratose or bistratose and attaches to underwater substrates via a short stalk and holdfast. The chloroplast is single, central, stellate, with a pyrenoid. Asexual reproduction proceeds via monospores or polyspores. During sexual reproduction, carpogonia and spermatangia develop from vegetative Cells located along the edges of the blade. A typical trichogyne is absent, and sometimes only a short, rudimentary, papilla-like one develops.

Porphyra belongs to the group of edible algae, known as red laver (sea lettuce), and has been introduced into commercial aquaculture. In Ukraine, it is known from the Black Sea, where it actively vegetates from November to May and is cultivated under artificial conditions.