Pteridophyta

Pteridophytes are seedless plants. They reproduce by tiny spores. They have many traits (vascular, seedless plants that reproduce via spores) like old plants from long ago. Pteridophytes don’t make flowers or seeds like many other plants do.

Types of Pteridophytes

Pteridophytes are divided into four groups. Each group is different in how it grows and makes spores.

1. Psilopsida

These are the oldest and simplest pteridophytes.
Their stems are green and dichotomously branched.
They have rhizoids, which are like roots but not real roots.
They mostly do not have true leaves. May have small, scale-like appendages.
Spores grow in a part called a synangium.
Examples: Psilotum and Tmesipteris.

2. Lycopsida

Known as club mosses because they look like moss.
They have roots, stems, and leaves.
They have true roots. Roots arising from stems are adventitious.
They have modified stems called rhizophores that develop roots.
They make spores that can be homosporous or heterosporous.
Examples: Selaginella and Lycopodium.

3. Sphenopsida

Also called horsetails.
They have jointed stems and tiny scaly leaves.
Roots arise from nodes of underground stems (rhizomes).
Most Sphenopsida (Equisetum) produce homosporous spores in cone-like parts called strobili.
Example: Equisetum.

4. Pteropsida

These are ferns.
Ferns have real roots, stems, and leaves.
They make spores that can be one kind or two kinds.
Male cells have tiny tails called flagella to swim in water.
Examples: Pteris, Dryopteris, etc.

Important Features of Pteridophytes

First Plants on Land

Life started in water. After many years, plants moved to land. Pteridophytes were some of the first land plants.

No Seeds but Have Vascular Tissue

Pteridophytes do not have seeds. They use spores to reproduce.
They have tubes (vascular tissue) inside their body to carry water and food.
They lack true xylem vessels and companion cells in most species.

Have Real Roots, Stems, and Leaves

Their body has real roots to take water from the soil.
Their stems hold the plant up.
Leaves make food using sunlight.

Spores Grow Inside Sporangia

Spores grow inside parts called sporangia.
Spores can be all the same (homosporous) or two different kinds (heterosporous).

Sporangia Grow on Sporophylls

Sporangia grow on leaves called sporophylls.
The tips of these leaves often curl inward to protect the spores (in many Pteropsida).

Sex Organs Have Many Cells

Male sex organs are called antheridia.
Female sex organs are called archegonia.
Both have many cells (multicellular gametangia). Antheridia make sperm, and archegonia make eggs.

Life Cycle of Pteridophytes

There are two stages in a pteridophyte's life: sporophyte and gametophyte.
The sporophyte is bigger and makes spores in sporangia.
The gametophyte is smaller and makes male and female sex organs.

Types of Gametophytes

Dioicous - Male and female gametophytes grow separately.
Monoicous - One gametophyte has both male and female parts.
Protandrous - Male parts mature first, then female parts (monoicous gametophytes).
Protogynous - Female parts mature first, then male parts (monoicous gametophytes).

Water is needed because sperm swim through water to reach the egg.

Examples of Pteridophytes

Scientific Name	Common Name	Description
Psilotum	Whisk Fern	Simple plants with no leaves.
Dicksonia	Tree Fern	Tall ferns that look like small trees.
Selaginella	Spikemoss	Small plants with special types of spores.
Lycopodium	Club Moss	Moss-like plants that grow close to the ground.
Equisetum	Horsetail	Plants with jointed stems and cone-like spore parts.
Pteris	Fern	Common ferns with large green leaves.
Dryopteris	Wood Fern	Ferns that grow well in shady, damp places.
Adiantum	Maidenhair Fern	Delicate ferns with small, fan-shaped leaves.
Man Fern	Angiopteris	A large, tree-like type of fern.
Silver Fern	Cyathea dealbata	Fern is known for its silvery underside of leaves.

Summary

Pteridophytes are seedless plants that reproduce by spores. They have true roots, stems, and leaves. They were early plants to live outside water. Their life cycle includes alternation of generations: a dominant sporophyte produces spores, and a smaller gametophyte produces gametes. Ferns and horsetails are common types.