Bryophytes
- A bryophyte spore is haploid
- A haploid cell has one set of chromosomes, a diploid cell has two
- In humans, the egg and sperm cells are haploid
- When they unite, the resulting cell is diploid and the ensuing embryo continues its development as a diploid individual
- Each parent has contributed one set of chromosomes
Life cycle
- A bryophyte spore germinates and produces an often algal-like mat, called a protonema
- the leafy or thalloid stage of the gametophyte develops from the protonemal stage
- The protonemata are almost always ephemeral
- Amongst the mosses there is a small number of species in which the protonemata are persistent and the leafy plants are ephemeral
- The spore was haploid and so are the resulting protonema and the ensuing leafy or thalloid stages
- The male and female sex organs, the antheridia and the archegonia, are produced on the gametophytic plants
- Haploid sperm are released from the antheridia
- when a haploid sperm reaches a haploid egg in an archegonium the egg is fertilized to produce a diploid cell
- This cell will develop into the diploid sporophyte
- the tissue in the embryonic sporophyte differentiates
- By the time the sporophyte has matured the spore capsule will contain haploid spores
Examples
- mosses
- liverworts
- hornworts