stigma(redirected from malpighian stigmas)
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, one of the four basic parts of a flower, the central structure around which are arranged the stamens, the petals, and the sepals. The pistil is usually called the female reproductive organ of a flowering plant, although the actual reproductive structures are microscopic.
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stigmaany physical or social attribute or sign (e.g. physical deformity or a criminal record) which so devalues an actor's social identity as to ‘disqualify from full social acceptance’ (GOFFMAN, 1964). Different implications follow for the stigmatized person according to whether the stigma is visible (the individual is obviously ‘discredited’), or hidden (the individual is potentially ‘discreditable’). The latter allows a greater number of options to the stigmatized person to manage his or her stigma. But in both cases the actor's problem lies in finding a means of limiting, or even turning to some advantage, the damaging effects of the stigma. As well as of interest in its own right, the study of stigmatized identities also throws light on the social construction of ‘normal’identities (see DEVIANCE).
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.
(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.
in ancient Greece, a mark or brand inflicted on the body of a slave or criminal.