peristome

American  

[per-uh-stohm] / ˈpɛr əˌstoʊm /

noun

1. Botany. the one or two circles of small, pointed, toothlike appendages around the orifice of a capsule or urn of mosses, appearing when the lid is removed.

2. Zoology. any of various structures or sets of parts that surround or form the walls of a mouth or mouthlike opening.

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peristome British  

/ ˈpɛrɪˌstəʊm /

noun

1. a fringe of pointed teeth surrounding the opening of a moss capsule

2. any of various parts surrounding the mouth of invertebrates, such as echinoderms and earthworms, and of protozoans

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peristome Scientific  

/ pĕr′ĭ-stōm′ /

1. A fringe of toothlike appendages surrounding the mouth of the spore capsule of some mosses. The teeth unfold under damp conditions and curl up under dry conditions to disperse spores gradually.

2. The area or parts around the mouth in certain invertebrates, such as the echinoderms.

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Other Word Forms

• peristomal adjective
• peristomatic adjective
• peristomial adjective

Etymology

Origin of peristome

From the New Latin word peristoma, dating back to 1790–1800. See peri-, -stome

Example Sentences

A structure called a peristome increases the spread of spores after the tip of the capsule falls off at dispersal.

From Textbooks • Jan. 1, 2015

In common with all Coelenterate animals, the walls of the columnar body and also the tentacles and peristome of Actinia are composed of three layers of tissue.

From Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 2 "Anjar" to "Apollo" by Various

The sporogonium is of large size and highly organized, though it presents peculiar features in the peristome.

From Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria" by Various

During each forward movement the column is arched downwards so that the peristome is in contact with the surface along which the animal is moving.

From Freshwater Sponges, Hydroids & Polyzoa by Annandale, Nelson

When moist the peristome closes hygrometrically over the orifice more or less; when drier the teeth or processes commonly bend outward or recurve; and then the spores more readily escape.

From The Elements of Botany For Beginners and For Schools by Gray, Asa