[sawr-ahy, sohr-ahy]
plural of sorus. Unabridged


[sawr-uhs, sohr-]
noun, plural sori [sawr-ahy, sohr-ahy] .
Botany. one of the clusters of sporangia on the back of the fronds of ferns. See diag. under fern.
Mycology. a soruslike spore mass of certain fungi and lichens.

1825–35; < Neo-Latin < Greek sōrós heap Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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World English Dictionary
sori (ˈsɔːraɪ)
the plural of sorus

sorus (ˈsɔːrəs)
n , pl -ri
1.  a cluster of sporangia on the undersurface of certain fern leaves
2.  any of various similar spore-producing structures in some lichens and fungi
[C19: via New Latin from Greek sōros a heap]

Collins English Dictionary - Complete & Unabridged 10th Edition
2009 © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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American Heritage
Science Dictionary
sorus   (sôr'əs)  Pronunciation Key 
Plural sori (sôr'ī)
  1. A cluster of sporangia borne on the underside of a fern frond. A sorus is sometimes covered by an indusium. Also called fruitdot.

  2. A reproductive structure consisting of masses of spores, characteristic of certain fungi such as rusts and smuts.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica


in botany, brownish or yellowish cluster of spore-producing structures (sporangia) usually located on the lower surface of fern leaves. A sorus may be protected during development by a scale or flap of tissue called an indusium. In rust and smut fungi, a sorus is a spore mass produced on the leaf of an infected plant. Reproductive structures called sori also occur in various species of marine algae. See also spore.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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Example sentences
All leaflets with sunken sori and sori with emerging filaments will be removed.
If you turn one of the fronds over you may see the round sori, clusters of spore-producing structures, on the underside.
In addition, the sori of fragile fern are nearly round, compared to the more elongate sori of the wall-rue spleenwort.
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