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The general meaning of monoecious or monoicous, monocous (from Greek: mono, single, oikos, house) is having male and female reproductive organs in the same plant or animal, as opposed to dioecious or diocious (Greek: dia (diairo: "divide") + oikos, "house").

Synonymous with "mono-*" is syno-*. Synonymous with "dio-*" are paro-* and hetero-*. For example, "synoecious", "heteroecious", and other combinations.

In zoology, the preferred terminology has become hermaphrodite, rather than "monoecious", while botany has a more specific usage of the terms. An exception are lower animals, e.g., the phylum of annelids (that covers worms and leeches): they may be monoecious (the same animal bears both ova and sperm) or dioecious.

A monoecious plant produces male and female gametophytes in the same sporophyte, in contrast to dioecious plants, in which a single plant may have only either male or female organs. See Sexual reproduction of plants.

  • Monoecious - having unisexual flowers, conifer cones, or functionally equivalent structures of both sexes appearing on the same plant;
  • Dioecious - having unisexual flowers, conifer cones, or functionally equivalent structures occurring on different individuals;
  • Because many dioecious conifers show a tendency towards monoecy (that is, a female plant may sometimes produce small numbers of male cones or vice versa), these species are termed subdioecious.

Bryophyte sexuality

Bryophyte are generally gametophyte-oriented; that is, the normal plant is the haploid gametophyte, with the only diploid structure being the sporangium in season. As a result, bryophyte sexuality is very different from that of other plants. There are two basic categories of sexuality in bryophytes:

  • Monoicous bryophytes produce both antheridia (male organs) and archegonia (female organs) on the same plant body.
  • Dioicous bryophytes produce only antheridia or archegonia on a single plant body.

Some bryophyte species may be either monoicous or dioicous depending on environmental conditions. Other species grow exclusively with one type of sexuality.

Occasionally the terms "monoecious (dioecious)" and "monoicous (dioicous)" may be used interchangeably, but there is a tendency to restrict monoecious and dioecious only to seed plants, which refer to whether or not an individual sporophyte plant bears one or both kinds of gametophyte.

Role in Survival

There are both advantages and disadvantages in being Monoicous and Dioicous. Organisms who are Monoicous benefit because they almost always are capable of reproducing, since there is no need to find a partner of another gender.

However, Dioicous organisms, on the other hand, have the benefit of trading genes with other members of the species, thus promoting evolution and the natural selection of desirable traits. However, they fall short in low populated areas, since they must find a breeding partner of the opposite gender. When only one sex of a species is left, the species is typically considered extinct and the only possible ways to save the species is through cloning or interbreeding with a closely related species, producing a hybrid. Also if populations reach critically low numbers ("Bottleneck"), they also may increase inbreeding due to the reduced pool of possible mates, and lower the number of available allelles for evolution, and in certain species, even have an inbreeding depression effect, where reproduction is lowered, or even incompatible, or may produce malformed offspring in certain species.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Monoicous". A list of authors is available in Wikipedia.
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