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Alteration of generations in a complete life cycle, especially of a dioecious and hermaphroditic generation.
Having heteromorphic perfect flowers with respect to lengths of the stamens or styles.



(heterostylism), unequal lengths of the styles in the pistils of flowers of different plants of the same species. The position of the anthers, on the stamens, corresponds to this pattern; in the dolichostylous (long-styled) flowers they are lower than the stigma and in the short-styled flowers they are higher. Heterogony is found in genera Primula, Pulmonaria, Fagopyrum, some species of Gentiana, and other plants. The purple loosestrife has flowers of three types with styles of short, long, and intermediate length. Differences in the size of the pollen, the length of the papillae of the stigma, and other variations in the characteristics of the flowers are often associated with heterogony. The results of pollination are better if pollen from short-styled flowers falls on long-styled flowers, and vice versa; heterogony thus hinders self-pollination and favors the cross-pollination of plants.



one of the forms of alternation of generations in animals in which sexual generations replace each other (in contrast to metagenesis, in which the sexual generations are replaced by asexual ones).

Heterogony is observed only in invertebrates: flatworms, roundworms, rotifers, crustaceans (the water fleas of the genus Daphnia), and insects (grape phylloxera, aphids, gall wasps, and Adelges). Three types of alternation are distinguished. There may be alternation of a dioecious with a hermaphroditic generation. For example, in the round worm Rhabdonema nigrovenosum the hermaphroditic generation parasitizes the lungs of frogs, but the dioecious generation is free living. In the second type there is alternation of dioecious generations that develop from fertilized eggs with generations that develop from eggs that did not require fertilization. For example, in some grass aphids a series of parthenogenetic viviparous generations is replaced in the fall by a generation of males and females that lay the winter eggs. In the spring parthenogenetic viviparous females once again hatch from the eggs. Finally, there may be alternation of sexual generations that are varied in structure (for example, alternation of generations in butterflies with seasonal variation in coloring).

Heterogony is the specific adaptation for reproduction of progeny under changing conditions of development. Through parasitism, heterogony provides the possibility of making use of the advantages of existence inside the host’s body and provides for the maximum increase in the quantity of newborn individuals, thus promoting a greater diffusion of a given species.

References in periodicals archive ?
The heterogonous PW population collected from geographically vast areas in Pakistan with varying ecological conditions is the indicator that multiple introductions have occurred, which has led to the successful invasion along with the environmental effects.
Non Hodgkin's lymphomas are heterogonous group of malignancies of lymphoid system, 40 Percent arising from extra nodal sites.
In 2 cases (33%), a CT demonstrated soft tissue mass with calcifications and heterogonous enhancement after contrast injection mimicking a renal tumour (Fig.
The sample is heterogonous in some degree, but the predominance of those who graduated economic sciences and business administration, humanities or communication sciences is probably not related with a wider preference for travelling abroad of these categories of persons.
In general, it appears that, globally, poverty not only has increased but also has created a highly heterogonous population of the poor.
2005) stated that the Freundlich isotherm is a heterogonous binding model and is widely applicable in measuring the heterogeneity of soils.
2002) are aware that in the modern society, occupation is an increasingly flexible and heterogonous category, since occupations change, primarily as regards tasks and duties performed by an individual in a certain work process.
Thus, infection with ETEC expressing certain CFs provided highly significant protection against re-infection with fully virulent ETEC expressing the homologous, but not heterogonous ETEC CFs (14).
This high spatial resolution is well suited for monitoring evapotranspiration on heterogonous landscapes.
In other words, this transnational fairy tale validates the US capitalist-consumer society, celebrating its "free" market system, its heterogonous, multi-cultural ambience, and its relative security and order that differs greatly from the denigrating condition captured on the lawless "Colombian side.
Oocyte-granulosa cell heterogonous gap junctions are required for the coordination of nuclear and cytoplasmic meiotic competence.