Moss Life Cycle Diagram Labeled – Spore to Sporophyte

All 14 stages and parts on the diagram

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Spore to plant 5

Spores Tiny grains that drift on the air. Each can start a new moss.
Protonema The green branching thread a spore grows into.
Bud It forms on the protonema and grows into a leafy plant.
Gametophyte (leafy plant) The leafy green moss plant. It makes the sperm and the eggs.
Rhizoids Fine threads that anchor the plant. They are not true roots.

Sperm and egg 4

Antheridium The male organ. It makes the sperm.
Sperm Tiny swimmers from the antheridium. They need water to reach the egg.
Archegonium The female organ: a flask with a long neck and one egg.
Egg It sits in the base of the archegonium. A sperm fertilizes it.

The sporophyte 5

Young sporophyte It grows from the fertilized egg, on top of the leafy plant.
Seta (stalk) The long stalk of the sporophyte. It lifts the capsule into the air.
Calyptra (cap) A loose cap over the capsule, left over from the archegonium.
Capsule (sporangium) The urn at the top of the seta. The spores form inside it.
Operculum (lid) The lid of the capsule. When it comes off, the spores can leave.

How this list was compiled: Every name was checked on 2026-09-30 against sources read that day; a name is kept only when two of them use it. (1) John N. Martin, Botany for Agricultural Students, 1919, public domain, https://archive.org/details/botanyforagricul00mart (true mosses: the leafy green plant is the gametophyte, with rhizoids; club-shaped antheridia and flask-shaped archegonia with long necks stand on the stem tip, in many mosses on the same plant, in others on separate plants; the sperms swim down the neck when there is moisture and fertilize the egg; the fertilized egg grows in place into the sporophyte, with a foot, a stalk called the seta and a sporangium, or capsule, in which the spores are produced; the enlarged archegonium is carried up as a pointed cap; the lid, or operculum; a spore first produces a branching filament, the protonema, and the leafy plants grow from buds on it; one protonema may produce many buds). (2) Wikipedia, text only: Moss, https://en.wikipedia.org/wiki/Moss (the life cycle starts with a spore that germinates to produce a protonema; from it grows the gametophore, with stems and leaves; rhizoids anchor the plant; antheridia and archegonia; in the presence of water sperm swim to the archegonia; the sporophyte is a long stalk, the seta, and a capsule capped by the operculum, sheathed by the calyptra, the remains of the archegonium, which usually drops off once the capsule is mature; a mat of protonemata may grow several shoots, a clump of moss), Protonema, https://en.wikipedia.org/wiki/Protonema (the bud), Sporophyte, https://en.wikipedia.org/wiki/Sporophyte (the sporophyte develops from the zygote, the fertilized egg cell, within the archegonium; young sporophytes of a moss), and Archegonium, https://en.wikipedia.org/wiki/Archegonium . (3) C. Stuart Gager, Fundamentals of Botany, 1916, public domain, https://archive.org/details/fundamentalsofbo00gagerich (chapter XV, Life history of a moss: antheridia with sperms that bear two cilia; archegonia with a neck and a venter containing the egg; the capsule with its spores; the top of the archegonium carried up as a cap, the calyptra; the operculum). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain curves; own work, nothing traced. Licence: own work

How it works

This moss life cycle diagram labeled in three steps starts with a spore. It grows into a green thread, the thread buds into leafy plants, a sperm reaches an egg, and a capsule sheds new spores.

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Two generations take turns

The leafy plant is the gametophyte. It makes sperm in antheridia and eggs in archegonia. A fertilized egg, the zygote, grows into the sporophyte: a stalk and a capsule that stay attached to the leafy plant. Spores from the capsule start the next gametophyte.

Why moss needs water

The sperm must swim to the egg, so fertilization happens only when the plants are wet.

A spore does not grow straight into a leafy plant. It makes the protonema first.
In many mosses one plant carries both antheridia and archegonia. This drawing shows a kind with separate plants.

Questions and answers

What are the stages of the moss life cycle?

Spore, protonema, bud, leafy gametophyte, sperm and egg, fertilized egg, sporophyte, then spores again. The leafy plant and the sporophyte are the two generations that take turns.

What is the protonema?

The first thing a moss spore grows into: a branching green thread that creeps over the ground. Buds on it grow into the leafy plants, and one protonema can make many.

What is the difference between the gametophyte and the sporophyte?

The gametophyte is the leafy green plant, and it makes sperm and eggs. The sporophyte is the stalk and capsule that grow from a fertilized egg, and it makes spores.

What are the calyptra and the operculum?

Both cover the capsule. The calyptra is a loose cap left over from the archegonium, and it usually falls off as the capsule ripens. The operculum is the lid of the capsule itself.

How do I label the structures on this diagram of a moss?

Press Show me the labels first to read every name in place, from the spores to the operculum, then answer the questions. The same names fit a textbook figure of the moss life cycle.