• Webster's Revised Unabridged Dictionary
    • n Macrocystis (Bot) An immensely long blackish seaweed of the Pacific (Macrocystis pyrifera), having numerous almond-shaped air vessels.
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Century Dictionary and Cyclopedia
    • n macrocystis A monotypic genus of gigantic seaweeds belonging to the Laminariaceæ. When fully grown the frond consists of a much-branched root, from which arise many filiform simple or branched stems, naked below but furnished above with numerous unilateral lanceolate petiolate leaves, having thin petioles enlarged into pear-shaped or oblong air-cells. The lateral leaves have their edges directed toward the stem, and are so far vertically disposed; and the stem itself when unbroken always terminates in an oblique leaf broader than the rest and having one or more slits in its base. This terminal leaf is the growing-apex, and from the development of the slits in the base new lateral leaves are gradually separated. The spores form dense, cloud-like, irregular patches on small radical leaves. M. pyrifera, the only species, girds the southern temperate zone in its distribution. The stems, which are the longest known in the vegetable kingdom, vary from 5 feet to several hundred feet in length, and Hooker observed them near the Crozet Islands fully 700 feet long.
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Webster's Revised Unabridged Dictionary
NL. See Macro-, and Cyst


In literature:

"A Naturalist's Voyage Round the World" by Charles Darwin
The Macrocystis pyrifera, an Algae, is the largest of all known plants.
"Scientific American Supplement, No. 384, May 12, 1883" by Various
Macrocystis and Nereocystis are also giant members of this sub-order.
"Sea-Weeds, Shells and Fossils" by Peter Gray