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.

---

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

---

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.

---

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 Polytrichum a membranous epiphragm stretches across the wide mouth of the capsule between the tips of the short peristome teeth, and closes the opening except for the interspaces of the peristome.

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

On the right edge of the peristome are large, powerful cilia.

From Marine Protozoa from Woods Hole Bulletin of the United States Fish Commission 21:415-468, 1901 by Calkins, Gary N. (Gary Nathan)

More usually there is a peristome, consisting of one or two series of teeth, which serves to narrow the opening and in various ways to ensure the gradual shedding of the spores in dry weather.

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

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