Life › Seas, forests & the move to land › Plants colonize land
Seeds
by c. 365 million years ago· Evolutionary innovation· Plants & fungi
Well establishedStrong fossil, genetic or geological evidence.
Seeds, an embryo plant packed with food inside a protective coat, appeared by about 365 million years ago, freeing plants from wet ground.
See it on the Life map →What happened
Earlier land plants reproduced by spores, and their sperm had to swim through water to reach eggs. Seed plants kept the egg in a protective case on the parent, fertilized it with wind-blown pollen, and released a sealed embryo with its own food supply. The oldest seeds, such as Elkinsia from West Virginia, are about 365 million years old; Runcaria from Belgium, about 385 million, may be a forerunner. Early seed plants are called 'seed ferns'.
Why it matters
Seeds let plants settle dry uplands and wait out bad seasons, leading to conifers, cycads, ginkgos and eventually flowering plants, including every grain crop.
Think of it like
Like a spore with a packed lunch and a hard case: the embryo travels with its own food and protection.
The evidence (fossils, genes, rocks)
Fossil seeds and ovules from Late Devonian rocks in West Virginia, Belgium and elsewhere, plus the anatomy and DNA of living seed plants.
Still debated
How seeds evolved step by step from spore-bearing plants, and whether Runcaria is truly an early stage, are still discussed.
Connections (2)
▸Seeds were borne by GlossopterisWell established
The connection
Glossopteris was a seed plant. Instead of releasing spores that need wet ground, it produced seeds on small structures attached to its leaves. Seeds let it reproduce through cold, seasonal climates, and it spread across the southern lands of Pangaea to become their dominant tree.
When and how
Gondwana (South America, Africa, India, Australia and Antarctica), about 299–252 million years ago, in cool, swampy lowlands after the late Paleozoic ice age.
The evidence
Fossils show seed-bearing organs attached directly to Glossopteris leaves, and mineral-filled specimens from Antarctica and Australia preserve the seeds in detail.
Debates and open questions
How its seed organs were built and which other seed plants were its closest relatives are still debated.
▸Seeds led eventually to Flowering plantsWell established
The connection
Flowering plants are a late branch of the seed plants. They added key twists: the seed develops inside a closed ovary that ripens into a fruit, and a second fertilization builds a food store for the embryo. Flowers, fruits and faster life cycles helped them overtake conifers and other older seed plants.
When and how
Seeds evolved by about 365 million years ago; flowering plants appear in the fossil record about 130 million years ago.
The evidence
DNA family trees place flowering plants within the seed plants, and their seeds share basic structure with those of conifers and cycads.
Debates and open questions
Which older seed plants are their closest relatives is unresolved, and the long gap between the first seeds and the first flowers is a puzzle.