Stigma

stigma: see pistil.

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stigma

1. a small scar or mark such as a birthmark

2. Pathol

a. any mark on the skin, such as one characteristic of a specific disease

b. any sign of a mental deficiency or emotional upset

3. Botany the receptive surface of a carpel, where deposited pollen germinates

4. Zoology

a. a pigmented eyespot in some protozoans and other invertebrates

b. the spiracle of an insect

5. Archaic a mark branded on the skin

6. Christianity marks resembling the wounds of the crucified Christ, believed to appear on the bodies of certain individuals

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stigma [′stig·mə]

(botany)

The rough or sticky apical surface of the pistil for reception of the pollen.

(invertebrate zoology)

The eyespot of certain protozoans, such asEuglena.

The spiracle of an insect or arthropod.

A colored spot on many lepidopteran wings.

(mechanics)

A unit of length used mainly in nuclear measurements, equal to 10^-12meter. Also known as bicron.

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Stigma

mark of Cain

God’s mark on Cain, a sign of his shame for fratricide. [O. T.: Genesis 4:15]

scarlet letter

the letter “A” for “adultery” sewn on Hester Prynne’s garments. [Am. Lit.: Hawthorne The Scarlet Letter]

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Stigma 

the plant organ that receives pollen during pollination. The stigma usually develops on the apex of the style; if there is no style, the stigma develops directly on the ovary. Stigmas vary in shape and are often covered with papillae or hairs that facilitate retention of the pollen.

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Stigma 

(1) A spiracle, or breathing opening, of the trachea and lungs on the body surface in many arthropods, including arachnids, onychophorans, myriapods, and insects. Arachnids usually have two pairs of stigmata, solpugids have three pairs, and most acarians have one pair. There are many stigmata scattered all over the body of onychophorans. In myriapods, the paired stigmata are usually situated on the abdominal side of all or only some truncal segments. There are one to ten pairs of stigmata on the thoracic and abdominal segments of insects. The stigmata of insects are furnished with a closing apparatus and can be opened and closed to regulate the exchange of gases.

(2) One of the numerous gill openings in the pharynx of ascidi-ans, a group of chordate animals.

(3) An ocellus, or eyespot, consisting of a mass of carotenoid grains and a photoreceptor in pigmented unicellular organisms of the class Mastigophora. The function of the stigma is to sense light.

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Stigma 

in ancient Greece, a mark or brand inflicted on the body of a slave or criminal.