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(kelps), an order of brown algae.
The Laminariales are the largest marine plants (to 10–15 m and more in length). The thallus consists of a simple or branched stipe, with rhizoids or a foot at the base, that bears one or more large blades. The conducting elements are sievelike tubules, similar in structure to the phloem cells of flowering plants, and serve to transport the products of photosynthesis. Laminariales grow by means of a growth zone located at the base of the blade and in the upper part of the stipe. The holdfasts and the stipe are usually perennial; the blades are destroyed annually. Once a year the blades yield zoospores, which develop into microscopic gametophytes. The sexual process is oogamy. The egg cell does not separate from the gametophyte; a new, large thallus (sporo-phyte) grows in its place.
There are about 30 genera of Laminariales (100 species), living principally in temperate and cold seas; they are found in all of the northern and Far Eastern seas of the USSR. Laminariales are used as food, for medical purposes (for example, sea kale), as cattle fodder, for fertilizer, and to obtain alginic-acid salts and mannitol.
LU. E. PETROV