Unit 2 | Life Cycles (Bryophytes aka Moss) | Biodiversity

Bryophytes

A moss, liverwort, or hornwort; a nonvascular plant that inhabits the land but lacks many of the terrestrial adaptations of vascular plants.

Bryophyte (Moss) Life Cycle | Step 1

Sporophyte (diploid, 2n)

The capsule (sporangium) makes haploid spores thru meiosis.

Bryophyte (Moss) Life Cycle | Step 2

Spores (haploid, n)

Released from capsule.

Each spore germinates → grows into a protonema (thread-like early stage).

Protonema develops into the gametophyte (leafy moss plant).

Bryophyte (Moss) Life Cycle | Step 3

Gametophyte (haploid, n)

This is the dominant stage (the green moss you see).

It produces gametes in special organs:

Antheridia → sperm

Archegonia → eggs

Bryophyte (Moss) Life Cycle | Step 4

Fertilization

Sperm swim through water to reach the egg (needs moisture).

Egg + sperm fuse → zygote (2n).

Bryophyte (Moss) Life Cycle | Step 5

Zygote → Sporophyte (2n)

Zygote develops into a new sporophyte.

Sporophyte grows attached to and dependent on the gametophyte.

Capsule makes spores again → cycle restarts.

Sporangium

spore capsule in which haploid spores are produced by meiosis

Protonema

mass of tangled green filaments in mosses that forms during germination

Gametophyte

The stage in the life cycle of a plant in which the plant produces gametes, or sex cells.

Bryophyte dominant stage

gametophyte