Question

Define the terms monoecious and dioecious with respect to sexuality in plant mentioning examples for each.

Answer 1

Hint: Define the terms based on the sexual organs present in the plant. Monoecious meaning single house and Dioecious meaning double house.

Complete answer:
The term monoecious and dioecious is in connection with the sexual reproduction of plants.
- Monoecious refers to plants that have both male and female reproductive parts and so can undergo sexual reproduction on its own and doesn’t need a partner. Examples include Cornus alba, Yellow Trout Lily, corn, Cucurbits, etc.
- On the other hand, dioecious plants are the plants with only one type of sexual organs (either male or female) and thus requires a partner of the opposite sex to undergo sexual reproduction. Examples: Willows, papaya, date palm, etc.

Features	Monoecious	Dioecious
Reproductive organs in the plant	Both male and female reproductive organ on the same plant	Either male or female reproductive organ per plant
Flowers	Unisexual flowers on the same plant	Unisexual flowers on different plants
Production of sexual gametes	The same plant produces both male and female gamete	A single plant produces either male or female gamete
Pollination	Self-pollination and cross-pollination	Cross-pollination
Seed production	All plants produce seeds	Only female plants (50%) produce seeds
Genetic variation	Low due to self-pollination or inbreeding	High due to cross-pollination
Zygosity (zygote type)	Increased homozygosity	Increased heterozygosity
Effect of reproductive isolation	No effects as they are capable of self-pollination	Reproductive isolation prevents pollination
Examples	Corn and Cucurbits	Papaya and Date palm

Additional Information:
- Monoecious plants are the bisexual species also known as Perfect flowers as they have both male and female sex organs. 90% of the plant species are monoecious plants.
- Dioecious plants are the unisexual plants also known as Imperfect flowers as they have only one (either male or female) sex organ. Only 10% of the plant species represent dioecious plants.
- Monoecious plants can be of two forms:
Plants having male and female sex organs on two different flowers, but both flowers are present on the same plant.
Plants having both male and female sex organs on the same flower of a plant.
Note: Unisexual flowers are the flowers that possess either male sexual organ (stamen) or female sexual organ (pistils/carpel) but not both. Bisexual flowers are flowers with both male and female sex organs.