CBSE Class 10 Answered
Bisexual flowers have both male (androecium) and female (gynoecium) reproductive units. These flowers are also called androgynous or hermaphroditic. Examples of plants with perfect or bisexual flowers include the lily, rose, and most plants with large showy flowers
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. Here, 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.
Dichogamy is common in flowering plants, and occurs when bisexual (perfect) flowers produce pollen when the stigmas of the same flower are not receptive of the pollen. This promotes outcrossing by limiting self-pollination. 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.