indusium

American  

[in-doo-zee-uhm, -zhee-uhm, -dyoo-] / ɪnˈdu zi əm, -ʒi əm, -ˈdyu- /

noun

indusia plural

1. Botany, Mycology. any of several structures having a netlike or skirtlike shape, as the membranous overgrowth covering the sori in ferns.

2. Anatomy, Zoology.

   1. an enveloping layer or membrane.

   2. a thin layer of gray matter on the corpus callosum.

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indusium British  

/ ɪnˈdjuːzɪəm /

noun

1. a membranous outgrowth on the undersurface of fern leaves that covers and protects the developing sporangia

2. an enveloping membrane, such as the amnion

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indusium Scientific  

/ ĭn-do̅o̅′zē-əm,-zhē- /

indusia plural

1. A thin membrane covering the sorus of a fern. The indusium often shrivels away when spores are ready to be dispersed.

2. Also called fruitcover

3. A cuplike structure fringed with hairs and located at the top of the style in flowers of the family Goodeniaceae (which includes the garden flowers lobelia and scaevola). Pollen is deposited into the indusium by the anthers of the same flower and, as the style grows, carried up for dispersal by pollinating insects.

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Other Word Forms

Derived Forms

• indusial
  adjective

Inflected Forms

noun

• indusia
  plural

Etymology

Origin of indusium

1700–10; < New Latin; Latin: kind of tunic, perhaps < Greek éndys ( is ) dressing, dress ( endý ( ein ) to put on + -sis -sis ) + Latin -ium, for Greek -ion noun suffix

Example Sentences

When the fruit is ripe, the indusium is something of a lilac colour, spotting the frond in double rows—as you see it there.

From The Old Helmet, Volume I by Warner, Susan

Sori round, borne on the veins; indusium fixed under the sorus, divided into segments or into slender filaments.

From The Manual of the Botany of the Northern United States Including the District East of the Mississippi and North of North Carolina and Tennessee by Gray, Asa

The indusium is formed of the altered margin of the pinnule, at first reflexed to the midrib, giving it a pod-like appearance, but at length opening out flat and exposing the sporangia.

From The Fern Lover's Companion A Guide for the Northeastern States and Canada by Tilton, George Henry

The beech ferns are often classed with the polypodies, because, like them, they have no indusium; but in other ways they are more akin to the wood ferns.

From The Fern Lover's Companion A Guide for the Northeastern States and Canada by Tilton, George Henry

Small ferns with fruit-dots borne beneath the revolute margin of the pinnules, at first roundish, but soon confluent into a narrow band without indusium.

From The Fern Lover's Companion A Guide for the Northeastern States and Canada by Tilton, George Henry