This stuff is extremely basic plant bio man! I just cut this from wiki. You really need to grab a used plant bio book and read it cover to cover while taking notes (no highlighting) and doing all the exersizes. If your interested in this kind of stuff I promise you will not be dissapointed! Not only will you understand breeding better but it will teach you what is truly needed to grow amazing plants. steer you away from all this heard mentality (like cutting leaves off or using high PK fertilizer in the face of the plants overall health declining).
[h=3]Individual plant sexuality[/h]Many plants have complete flowers that have both male and female parts, others only have male or female parts and still other plants have flowers on the same plant that are a mix of male and female flowers. Some plants even have mixes that include all three types of flowers, where some flowers are only male, some are only female and some are both male and female. A distinction needs to be made between arrangements of sexual parts and the expression of sexuality in single plants versus the larger plant population. Some plants also undergo what is called
Sex-switching, like
Arisaema triphyllum which express sexual differences at different stages of growth. In some arums smaller plants produce all or mostly male flowers and as plants grow larger over the years the male flowers are replaced by more female flowers on the same plant.
Arisaema triphyllumthus covers a multitude of sexual conditions in its lifetime; from nonsexual juvenile plants to young plants that are all male, as plants grow larger they have a mix of both male and female flowers, to large plants that have mostly female flowers.[SUP]
[4][/SUP] Other plant populations have plants that produce more male flowers early in the year and as plants bloom later in the growing season they produce more female flowers. In plants like
Thalictrum dioicum all the plants in the species are either male or female.
Terminology:
- Hermaphrodite. In hermaphroditic species, each reproductive unit (as in flower, conifer cone or functional equivalent) of each individual has both male and female structures. In angiosperm terminology a synonym is monoclinous from the Greek "one bed".
- Monoecious. In monoecious species, each individual has reproductive units that are merely female and reproductive units that are merely male. The name derives from Greek "monos" (one) and "ecos" (home). Individuals bearing separate flowers of both sexes at the same time are called simultaneously or synchronously monoecious. Individuals that bear flowers of one sex at one time are called consecutively monoecious; plants may first have single sexed flowers and then later have flowers of the other sex. Protoandrous orprotandrous describes individuals that function first as males and then change to females; protogynous describes individuals that function first as females and then change to males.
- Dioecious. In dioecious species, each individual has reproductive units that are either merely male or merely female. That is, no individual plant of the population produces both microgametophytes (pollen) and megagametophytes (ovules).[SUP][5][/SUP] From Greek for "two households". [Individual plants are not called dioecious; they are either gynoecious (female plants) or androecious (male plants).]
- Androecious, plants producing male flowers only, produce pollen but no seeds, the male plants of a dioecious population.
- Gynoecious, plants producing female flowers only, produces seeds but no pollen, the female of a dioecious population. In some plant populations, all individuals are gynoecious with non sexual reproduction used to produce the next generation.
- Subdioecious, a tendency in some dioecious populations to produce individuals that are not clearly male or female. The population produces normally male or female plants but some may be monoecious, hermaphroditic, or monoecious/hermaphroditic, with plants having perfect flowers, both male and female imperfect flowers, or some combination thereof, such as female and perfect flowers. Flowers may be in some state between purely male and female, with female flowers retaining non-functional male organs or vice versa. The condition is thought to represent a transition between hermaphroditism and dioecy.[SUP][6][/SUP][SUP][7][/SUP]
- Gynomonoecious has both hermaphrodite and female units.
- Andromonoecious has both hermaphrodite and male units.
- Subandroecious has mostly male flowers, with a few female or hermaphrodite flowers.
- Subgynoecious has mostly female flowers, with a few male or hermaphrodite flowers.
- Polygamy, plants with male, female, and perfect (hermaphrodite) flowers on the same plant, called trimonoecious orpolygamomonoecious plants, (see next section for use for plant populations).[SUP][8][/SUP] A polygamous inflorescence has both unisexual and bisexual flowers.[SUP][9][/SUP]
- Trimonoecious (polygamous) - male, female, and hermaphrodite floral morphs all appear on the same plant.
- Diclinous ("two beds"), an angiosperm term, includes all species with unisexual flowers, although particularly those with onlyunisexual flowers, i.e. the monoecious and dioecious species.
[h=3]Plant population[/h]Often a species or a population within a species will have the same form of sexuality. Specific terms can then be used to describe the sexual expression of the group as a whole.
- Hermaphrodite, plants whose flowers have both male and female parts.
- Monoecious (meaning "one house" in Greek) plants have separate male and female flowers on the same plant. These plants are often wind pollinated. Examples of monoecious plants include corn (Zea mays),[SUP][10][/SUP]birch and pine trees,[SUP][11][/SUP] and most fig species.[SUP][12][/SUP]
- Dioecious (meaning "two houses" in Greek), all plants are either female or male. The American Holly (Ilex opaca) is a famous example.
- Androdioecious, both male and hermaphrodite plants present.
- Gynodioecious, both female and hermaphrodite plants present. In some plants, strictly female plants are produced by the degeneration of the tapetum, a shell-like structure in the anther of a flower where the pollen cells form,[SUP][13][/SUP]
- Gynoecy plants are all females in a population, often regulated by environmental factors like temperature, photo period or water availability.
- Polygamous, when there is a mix of hermaphrodite and unisexual plants in the natural population.[SUP][14][/SUP]
- Subdioecious, population of unisexual (dioecious) plants, with monoecious individuals too.[SUP][15][/SUP]
- Trioecious, sometimes used in place of subdioecious when male, female, and hermaphrodite plants are more equally mixed within the same population.
- Polygamodioecious, having bisexual and male flowers on some plants, and bisexual and female flowers on others.[SUP][16][/SUP]
About 11% of all angiosperms are strictly dioecious or monoecious. Intermediate forms of sexual dimorphism, including gynodioecy and
androdioecy, represent 7% of the species examined of a survey of 120,000 plant species. In the same survey, 10% of the species contain both unisexual and bisexual flowers.[SUP]
[17][/SUP]
The majority of plant species use
allogamy, also called cross-pollination or outcrossing, as a means of breeding. Many plants are self-fertile and the male parts can pollinate the female parts of the same flower and/or same plant. Some plants use a method known as
self-incompatibility to promote outcrossing. In these plants, the male organs cannot fertilize the female parts of the same plant; other plants produce male and female flowers at different times to promote outcrossing.
Sexual reproduction (involving meiosis and outcrossing) is the most common mode of reproduction among higher plants. As summarized by Bernstein and Bernstein, pp. 272-274.[SUP]
[18][/SUP] About 55% of higher plant species are principally sexual This includes plants that are dioecious and dichogamous. An additional 7% are partially sexual, i.e. partially self-fertilizing and partially cross-fertilizing. About 15% undergo meiosis, but are principally self-fertilizing, and significant out-crossing is lacking (autogamy). Only about 8% of higher plant species reproduce exclusively by non-sexual means. These include plants that reproduce vegetatively by runners or bulbils, or by
apomixis. The selective advantage of outcrossing sex (the predominant form of reproduction in plants) appears to be the masking of deleterious recessive mutations (reviewed by Bernstein and Bernstein, pp. 272-289[SUP]
[18][/SUP].
Dichogamy is common in flowering plants, and occurs when bisexual (perfect) flowers (or sometimes entire plants) produce pollen when the stigmas of the same flower is not receptive of the pollen. This promotes outcrossing by limiting what is called autopollination or self-pollination or selfing.[SUP]
[19][/SUP] These plants are called dichogamous. Some plants have bisexual flowers but the pollen is produced before the stigma of the same flower is receptive of pollen, these are described as
protandrous flowers; in a similar way,
protogyny describes flowers that have stigmas that can accept pollen before the same flower or plant sheds its pollen.[SUP]
[8][/SUP]
- Autogamy. Self-fertilization. Fusion of male and female gametes, usually from the same individual.
- Apomixis: Asexual reproduction through seeds
ddimebag
