Barley World

Sexual determination in plants

1. The degree of outcrossing ranges from complete (dioecy)……to……moderate (monoecy) ……to……(very) low (hermaphrodites)

2. Perfect flowers: 90% of angiosperms are hermaphrodites - they have perfect flowers. The ancestral and basal condition is hermaphroditic

A. The benefits of outcrossing often outweigh the drawbacks.

Pros

• Avoids inbreeding depression
• Promotes heterozygosity
• Promotes genetic variability

Cons

• Environmental conditions may limit pollen flow
• "Cost" of having two parents, only one of which bears seed

B. Even in the case of perfect flowers, there are ways of encouraging, or even requiring, outcrossing.

i. Self-incompatibility __________



Brassica spp. (perfect) 

Image 

More on incompatibility

 

ii. Male sterility ___________