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[sawr-uh s, sohr-] /ˈsɔr əs, ˈsoʊr-/
noun, plural sori
[sawr-ahy, sohr-ahy] /ˈsɔr aɪ, ˈsoʊr aɪ/ (Show IPA)
Botany. one of the clusters of sporangia on the back of the fronds of ferns.
Mycology. a soruslike spore mass of certain fungi and lichens.
Origin of sorus
1825-35; < New Latin < Greek sōrós heap Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for sorus
Historical Examples
  • The proper (often shield-shaped) covering of the sorus or fruit-dot in Ferns.

  • Indusium minute, concealed beneath the sorus, divided into a few beaded hairs.

    The Fern Lover's Companion George Henry Tilton
  • The indusium arises from a vein to which the sorus is attached.

    How to Know the Ferns S. Leonard Bastin
  • The sorus, as the group of sporangia is called, is surrounded by an enclosure from the leaf margin.

    How to Know the Ferns S. Leonard Bastin
  • Indusium hood-shaped, fixed centrally behind the sorus and arching over it, soon withering, often illusive.

    The Fern Lover's Companion George Henry Tilton
  • Commonly the spore-cases occupy only detached spots or lines, each of which is called a sorus, or in English merely a Fruit-dot.

  • The sorus is circular and is covered with an indusium which is notched or kidney-shaped.

    How to Know the Ferns S. Leonard Bastin
  • Indusium star-shaped, of a few irregular segments fixed beneath the sorus, often obscure.

    The Fern Lover's Companion George Henry Tilton
  • In this case the sorus is always near to the margin of the leaf, and the indusium or covering is cup-shaped.

    How to Know the Ferns S. Leonard Bastin
British Dictionary definitions for sorus


noun (pl) -ri (-raɪ)
a cluster of sporangia on the undersurface of certain fern leaves
any of various similar spore-producing structures in some lichens and fungi
Word Origin
C19: via New Latin from Greek sōros a heap
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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sorus in Science
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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