indusium

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in·du·si·um

 (ĭn-do͞o′zē-əm, -zhē-, -dyo͞o′-)
n. pl. in·du·si·a (-zē-ə, -zhē-ə)
An enclosing membrane, as that covering the sorus of a fern.

[Latin, tunic, perhaps alteration of Greek endusis, dress, from enduein, to sink into, put on : en-, in; see en-2 + duein, to sink.]

indusium

(ɪnˈdjuːzɪəm)
n, pl -sia (-zɪə)
1. (Botany) a membranous outgrowth on the undersurface of fern leaves that covers and protects the developing sporangia
2. (Zoology) an enveloping membrane, such as the amnion
[C18: New Latin, from Latin: tunic, from induere to put on]
inˈdusial adj

in•du•si•um

(ɪnˈdu zi əm, -ʒi əm, -ˈdyu-)

n., pl. -si•a (-zi ə, -ʒi ə)
1. Bot., Mycol. any of several structures having a netlike or skirtlike shape, as the membranous overgrowth covering the sori in ferns.
2. Anat., Zool.
a. an enveloping layer or membrane.
b. a thin layer of gray matter on the corpus callosum.
[1700–10; < New Latin; Latin: kind of tunic]
in•du′si•al, adj.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.indusium - a membrane enclosing and protecting the developing spores especially that covering the sori of a fernindusium - a membrane enclosing and protecting the developing spores especially that covering the sori of a fern
covering, natural covering, cover - a natural object that covers or envelops; "under a covering of dust"; "the fox was flushed from its cover"
sorus - cluster of sporangia usually on underside of a fern frond
References in periodicals archive ?
This group has 1- or 2-pinnate blades, axes with scales or adaxial pubescence, sessile to short-stalked segments, and few to many indusia.
The remains of sporangia and indusia were eliminated by a mesh with pores 0.
This differs by its larger fronds, broader and longer pinnae (to 25 x 4 cru; to 8 x 2 cru in Nitta 281) with more oblique and falcate segments, basal segments of ar least the distalmost pinnae strongly reduced, persistent stipe base scales, and relatively large, tan indusia.
Taxonomic and nomenclatural confusion has surrounded species of maidenhair ferns (Adiantum) with decompound, non-conform laminae and orbicular to reniform indusia.
It is characterized by large pinnate-pinnatisect leaves, sparse narrowly triangular petiole scales and caducous membranous indusia.
All three species are medium-sized, rhizomatous, herbaceous plants with 3-pinnate fronds and orbicular sori covered with reniform indusia (Fraser-Jenkins, 1993).
Lack of indusia makes Mesopteris distinct from other genera.
Sori marginal, under revolute margins of blade; indusia absent 12
9 m, 4-pinnate to 5-pinnate-pinnatifid, deltate-ovate, anadromous throughout; rachises, costae, and costules sparsely scaly abaxialy, the scales 1-3 mm long, linear-lanceolate, slightly tortuous, dark brown; basal pinnae 30-45 X 25-30 cm, ovate-oblong to triangular-oblong; ultimate segments 5-8 X 2-3 mm, obtuse to acute, often ascending and sometimes strongly so; tissue between the veins glabrous on both surfaces; sporangial stalks glabrous; indusia 1.
Leaf stalk (petiole) essentially lacking scales (may have a few near base); indusia hood-like: Cystopteris
8 mm long, 3-6-celled, acicular, lax, spreading; indusia fugacious, minute, consisting of a few hair-like scales, often covered by sporangia and apparently absent; spores cristate.