SEX - INFO
MALEThe flowers are male, having stamens but no carpels.
FEMALEThe flowers are female, having carpels but no stamens.
BISEXUALEvery flower on the plant has both male (stamens) and female (carpels) structures. Alternative names for bisexual are: androgynous, hermaphroditic, monoclinous and synoecious.
OR UNISEXUALThe plant can be either Monoecious or Dioecious, see below.
MONOECIOUSMany plants are Monoecious, that is have separate male and female flowers where both occur on the same plant. Monoecious plants can pollinate each other and (probably) themselves too.
DIOECIOUSMuch fewer plants are Dioecious where separate male and female flowers are on separate plants.
This has reproduction implications: both male and female plants need to be nearby in order for fertilisation of female flowers by male flowers to occur. If fertilisation does not occur, a female plant will not produce fruit or berries (but a male plant will always produce pollen).
& & POLYGAMOUSHaving both bisexual, male and female flowers on the same plant. Alternative names for polygamous are androgynomonoecious, polygamomonoecious and trimonoecious.
& GYNOMONOECIOUSHaving both bisexual/hermaphrodite and female flowers on the same plant.
EOR GYNODIOECIOUSHaving a mixture of bisexual/hermaphrodite flowers on some plants and only female flowers on other plants. These might include male plants, sterile plants (male sterile or female sterile) and hermaphrodite plants - and a little-known fourth class of partially male sterile plants where temperature influences sexual expression and the degree of male sterility but not in the former 3 classes. Examples of gynodioecious flowers include Buck's-horn Plantain, Bladder Campion, Devil's-bit Scabious and Meadow Saxifrage
& ANDROMONOECIOUSHaving both bisexual and male flowers on the same plant.
EOR ANDRODIOECIOUSHaving bisexual and male flowers on separate plants.
Heterostylous - having two forms of bisexual flower: Pin and Thrum, either of which can only fertilise the opposite form. Pin forms have a long style and short stamens, whereas thrum forms have long stamens and a short style. Because the pin and thrum forms are determined by genes, the same plant has either all pin flowers or all thrum flowers (the Author thinks). See Primrose for a much fuller explanation and for information on further forms.
Purple Loosestrife takes heterostyly to the third level where there are three types of flower morphs. It is thus Tristylous. Each flower morph has two types of stamens (but only one stigma). The two types of stamens are in sets of (nominally) six each. The first morphological type where the style is short and the two stamens are medium and long; the second morph has a medium length style and long and short stamens; the third morph has a long style with medium and short stamens. Pollen transferred from flowers of the same morph will not result in fertilisation because the individual morphs are self-incompatible. The three flower morphs are adapted to pollination by different insects. Generally, pollen from the stamen nearest to the stigma will pollinate the stigma.
Plant sexuality is not always so straightforward, there are many half-way houses and permutations on the above. Plant Reproductive Morphology