Title: Plant Reproduction | Organismal Biology
Headings: Plant Reproduction
Plant Reproduction
Learning Objectives
Sexual reproduction in plants: Alternation of Generations
Reproduction in angiosperms
Flower Structure
The Pollen Grain: the Male Gametophyte
The Embryo Sac: The Female Gametophyte
Double Fertilization
Avoiding self-pollination
Pollination Syndromes
Seed Dormancy and Germination
Fruit and Seed Dispersal

Content: Alternation of Generations. Image credit: Menchi, Wikimedia Commons. https://en.wikipedia.org/wiki/File:Sporic_meiosis.png
Though all plants display an alternation of generations life cycle, there are significant variations in different lineages of plants, consistent with their evolutionary history: In seedless non-vascular plants, or bryophytes (mosses), the haploid gametophyte is larger than the sporophyte (the plant structure that you see is the gametophyte); this is a gametophyte-dominated life cycle. The sporophyte is attached to and dependent on the gametophyte. ( By “dominated” we mean “the stage of the plant you can see by eye.”) In seedless vascular plants (ferns), the sporophyte is larger than the gametophyte (the plant structure that you see is the sporophyte), but the gametophyte is free-living and independent from the diploid sporophyte. The life cycle of angiosperms (flowering plants) and gymnosperms (conifers) is dominated by the sporophyte stage (the plant structure that you see is the sporophyte), with the gametophyte remaining attached to and dependent on the sporophyte (reverse of bryophytes).