Important Features of Gymnosperms: Naked Seeds and Cones

Gymnosperms are seed plants, and the seed is the whole story. Their seeds are not sealed inside a fruit. A pine seed sitting on the scale of a cone is the clearest example there is.

That one difference separates them from the flowering plants, which wrap their seeds in an ovary that becomes a fruit. Gymnosperms also carry pollen instead of swimming sperm, which frees them from needing wet ground to reproduce. This guide covers the features that define the group, and the ones that are common but not universal.

The Seed That Gives the Group Its Name

Naked Does Not Mean Unprotected

"Naked seed" is a description, not a complaint. It means the seed is not enclosed inside an ovary or fruit. It does not mean the seed has no coat.

Every gymnosperm seed still has a seed coat. The coat develops from the integument, the layer that surrounded the ovule before fertilization. Ginkgo even wraps its seed in a fleshy outer layer. What gymnosperms lack is the fruit that flowering plants build around the seed.

Where the Ovules Sit

An ovule holds a megasporangium, also called the nucellus, wrapped in one or more integuments. After fertilization the ovule becomes the seed. Because the ovule is carried on an open scale or stalk, its seed is exposed to the air.

Gymnosperms are heterosporous. They make two kinds of spore. A microspore develops into pollen, which is the reduced male gametophyte. A megaspore develops into the female gametophyte inside the ovule.

An opened Jeffrey pine cone. Each seed rests on a cone scale with no fruit around it, which is what "naked seed" means. Image: Maria Morrow, CC BY-SA 4.0, via Wikimedia Commons

Four Living Groups

Conifers Are the Largest Group

Conifers are the gymnosperms most people can name: pines, firs, spruces, cypresses, cedars and yews. They usually grow as woody trees or shrubs with needle-shaped or scale-shaped leaves, and they are the group that dominates cold and mountain forests today.

Cycads, Ginkgo and Gnetophytes

Cycads look like palms, with thick trunks and large compound leaves. Most bear big, conspicuous cones. Ginkgo is stranger still: only one species survives, Ginkgo biloba, with fan-shaped leaves that turn gold before they drop.

Gnetophytes are the odd group. Its three genera have so little in common that they were once placed in separate branches. Welwitschia carries two straggling leaves, Ephedra has jointed green stems, and Gnetum has broad leaves.

Group	Common members	Living species	One clear feature
Conifers	Pines, firs, spruces, cypresses, yews	About 650 to 700	Needle or scale leaves, woody seed cones
Cycads	Cycas, Encephalartos	About 360 to 380	Palm-like plants with large compound leaves
Ginkgo	Ginkgo biloba only	One	Fan-shaped leaves and a fleshy seed coat
Gnetophytes	Welwitschia, Ephedra, Gnetum	About 110 to 120	Three very different genera, with vessels in the wood

Add the groups together and about 1,100 to 1,200 gymnosperm species are alive. Counts move around as botanists split, merge and reclassify species, so treat the totals as close estimates.

A female cone of the cycad Encephalartos ferox. Cycads are gymnosperms, but they look nothing like a pine. Image: Yercaud-elango, CC BY-SA 4.0, via Wikimedia Commons

Cones, Pollen and a Life Cycle Without Free Water

Pollen Cones and Seed Cones

Most gymnosperms in this group carry two kinds of cone. Pollen cones, or microstrobili, are the male structures. They make microspores that become pollen grains. Seed cones, or megastrobili, are the female structures. They hold the ovules.

A pollen grain is not a sperm cell. It is a whole tiny plant stage. When it lands near an ovule it grows a pollen tube that carries the sperm cells to the egg.

A Pollen Tube Instead of a Swim

Ferns and mosses need a film of water so that sperm can swim. Gymnosperms solved that problem. Pollen travels on the wind or on an insect, and the pollen tube delivers the sperm cells directly.

Wind is not the only route. Many cycads are pollinated by insects, and insect pollination also happens among the gnetophytes. In Ephedra the method differs from one species to the next.

Not Every Cone Is Woody

Woody cones are a conifer habit, not a rule for the whole group. Ginkgo carries its ovules on stalks and never makes a typical female cone. A female Cycas uses loose, leaf-like structures instead of a tight cone.

Some conifer seed structures are fleshy. A yew seed sits in a soft red aril, and juniper cone scales fuse into a berry-like cluster. Neither one is a fruit.

Male pollen cones of Scots pine. They release pollen and then fall, while the female cones stay on the tree for years. Image: Rosser1954, CC BY-SA 4.0, via Wikimedia Commons

Wood, Leaves and Resin

Tracheid Wood, With One Exception

Most gymnosperm wood carries water through tracheids, long cells that both move water and help hold the trunk up. Vessel elements, the wider cells found in oak and maple, are missing from most gymnosperms.

The gnetophytes are the exception. Gnetum and its relatives do have vessels. That detail is real, but it does not make them close relatives of the flowering plants; that idea was tested and dropped.

Wood itself comes from the vascular cambium, a ring of dividing cells that adds new tissue each year and thickens the stem. Timber from conifers is called softwood and timber from flowering trees is called hardwood. Those are trade labels for the two groups, not a promise about how hard a board feels.

Needles, Scales and a Thick Cuticle

Many conifers have narrow needles or small scales, a thick waxy cuticle, and stomata sunk below the surface. Together those features limit water loss when the ground is dry or frozen.

Those adaptations are common, not universal. Cycads carry broad compound leaves. Ginkgo has wide fan-shaped leaves. Some gnetophytes have broad leaves too.

"Evergreen" fails as a rule as well. Larches and bald cypress are deciduous conifers that drop their needles every fall, and Ginkgo loses its leaves in a single golden week.

Resin

Pines and many other conifers make resin and store it in resin ducts. When bark is damaged, resin flows into the wound and hardens. It also discourages insects and fungi.

Resin is a conifer feature rather than a gymnosperm-wide one, so it does not belong on a list of defining traits. Fossilized resin is amber, and amber does not come only from conifers. Pine resin gives us turpentine and rosin.

A Ginkgo biloba leaf. Its fan shape and open veins look nothing like a pine needle, which is why gymnosperm leaves cannot be described as needles alone. Image: Dietmar Rabich, CC BY-SA 4.0, via Wikimedia Commons

Old Forests and Living Records

From Mesozoic Forests to the Boreal Zone

Gymnosperms, and conifers in particular, were widespread and often dominant through much of the Mesozoic Era. They are still the main trees of the boreal forest belt that circles the far north.

The Largest and the Oldest

The General Sherman giant sequoia is the largest living tree in the world by trunk volume. Great Basin bristlecone pines include the oldest known non-clonal trees, with estimated ages around 4,700 to 5,200 years.

What Flowering Plants Did Not Do

Flowering plants spread into more habitats and became the dominant group in most of them. They did not wipe gymnosperms out. Conifers and their relatives simply kept the cold, dry and high places where seeds and narrow leaves work well.

Key Terms in Plain English

Term	What it means here
Gymnosperm	A seed plant whose seeds are not enclosed in a fruit.
Naked seed	A seed carried in the open, not inside an ovary or fruit.
Ovule	The structure that holds the egg and becomes a seed after fertilization.
Integument	The layer around an ovule that develops into the seed coat.
Seed coat	The protective outer layer of a seed, present in gymnosperms too.
Pollen grain	The tiny male gametophyte stage, not a sperm cell.
Pollen tube	The tube a pollen grain grows to carry sperm cells to the egg.
Microspore	The spore that develops into a pollen grain.
Megaspore	The spore that develops into the female gametophyte.
Pollen cone	A male cone, also called a microstrobilus, that makes pollen.
Seed cone	A female cone, also called a megastrobilus, that holds ovules.
Tracheid	A long water-carrying wood cell of most gymnosperms.
Vessel element	A wider water-carrying cell, present mainly in gnetophytes here.
Vascular cambium	The growth layer that adds wood and thickens a stem.
Softwood	Timber from conifers, as opposed to hardwood from flowering trees.
Resin	A sticky conifer secretion that seals wounds and repels pests.
Aril	A fleshy covering around a seed, as on a yew.

Key Takeaways

• Gymnosperms are seed plants whose seeds are not enclosed in a fruit.
• Naked seed means no fruit around it, not that the seed lacks a coat.
• Four groups are alive: conifers, cycads, Ginkgo and gnetophytes.
• Pollen and a pollen tube replaced swimming sperm, so wet ground is not required.
• Tracheid wood, needle leaves and resin are common conifer traits, not rules.
• Gnetophytes have vessel elements, so gymnosperm wood is not vessel-free.

Frequently Asked Questions

Are all gymnosperms conifers?

No. Conifers are the largest group, but cycads, Ginkgo and the gnetophytes are gymnosperms too, and they look quite different.

Does a naked seed have no seed coat?

It does have one. Naked refers to the seed sitting in the open instead of inside a fruit. The coat comes from the integument of the ovule.

Do all gymnosperms have needle leaves?

No. Cycads have large compound leaves, Ginkgo has fan-shaped leaves, and some gnetophytes have broad leaves.

Are gymnosperms all evergreen?

No. Larches and bald cypress are deciduous conifers, and Ginkgo drops all of its leaves each autumn.

Key references
• Gymnosperm Database: What are gymnosperms?
• Yang et al. (2024): Living gymnosperms, an updated review
• Yang et al. (2022): Gymnosperm phylogeny and genome review
• CUNY OpenEd: Seed plants, gymnosperms
• Nepi et al.: Pollination in gymnosperms
• USDA Forest Service: Resins, amber and turpentine

Images: Wikimedia Commons, with the author and license named in each caption. This article is general science education.

Tracheophytes: How Plants Became Tall

A moss tops out at ankle height. A redwood reaches 115 metres. Both are land plants, but only one of them can move water up its own body. The difference is a set of pipes, and the plants that have them are called tracheophytes.

This post explains what those pipes are, how they work, and which plants have them.

What the Name Means

Tracheophyte comes from two Greek words. Trakheia means windpipe, and phuta means plants. It is a good name. The earliest conducting cells are hollow tubes joined end to end, with walls that are barred like the rings of a windpipe.

Rhynia had a bare upright stem and no true leaves, but it did carry conducting tissue — Image: Matteo De Stefano, CC BY-SA 3.0, via Wikimedia Commons

The group is also called the vascular plants, from the Latin vasculum, a duct. About 300,000 species are accepted, which is every land plant except the mosses. The earliest known tracheophyte is a plant called Cooksonia, from the mid-Silurian period, roughly 425 million years ago.

You will sometimes see vascular plants called "higher plants". That is an old label and it is not scientific. It implies a ladder of life with mosses at the bottom, which evolution does not work that way. Every living group has been evolving for exactly as long as every other one.

The Two Tissues That Define the Group

Botanists define a vascular plant by three things. It has conducting tissue, its dominant life stage is the sporophyte, and it has true roots, stems and leaves. The conducting tissue is the important one, and there are two kinds.

Xylem: dead tubes that carry water

Xylem moves water and dissolved minerals upward from the roots. The cells that do the work are dead by the time they are fully grown. An empty rigid tube is a far better pipe than a living one, because nothing inside it gets in the way of the water.

In flowering plants the pipes are wide vessels. In every other vascular plant they are narrower cells called tracheids. A tracheid wall contains lignin, the same stiff substance that stiffens wood, and it is what stops the tube collapsing under the tension of the water inside it.

The vascular bundles sit in a ring near the outside of the stem, each one carrying xylem inboard and phloem outboard — Image: Curtis Clark, public domain, via Wikimedia Commons

Phloem: living tubes that carry sugar

Phloem carries the products of photosynthesis, mostly sucrose, from the leaves to the growing shoots and roots. Its conducting cells are alive. That is the opposite of xylem, and the contrast is worth remembering: one tissue is a plumbing system and the other is a living conveyor.

Phloem cells are called sieve-tube members, joined end to end across perforated walls called sieve plates. A mature sieve-tube member has no nucleus and no ribosomes of its own. Neighboring cells called companion cells keep it alive. This one arrangement is why a sieve-tube member cannot simply repair itself when damaged.

The soft inner bark is phloem. Stripping it off a living tree is what girdling does, and it kills the tree from the inside — Image: Juha Kämäräinen, CC BY-SA 3.0, via Wikimedia Commons

Why they always come as a pair

Xylem and phloem sit right next to each other, and botanists call the combination a vascular bundle. Neither tissue works on its own for long. The xylem delivers water and minerals that the phloem needs to keep running, and the phloem delivers the sugar that powers the living cells doing the transport.

How Water Rises Without a Pump

It is tempting to picture a plant pumping water upward from its roots. It does not, and it barely spends any energy on the job at all. The mechanism is transpiration pull.

Water leaves the leaves through pores called stomata. As it evaporates from the wet cell walls inside a leaf, it curves the meniscus in the tiny tubes, and surface tension resists. Evaporation at the top of the water column pulls on the water below it. Each molecule escaping hauls up the next one.

Most of a plant's water leaves through these adjustable pores. Close them and the pull stops — Image: Charles Tschirhart, CC BY-SA 3.0, via Wikimedia Commons

It works because water molecules hydrogen-bond to each other, so they line up in a connected thread the whole height of the tree. Osmosis into the root helps push water in from the soil, but the pull is what does the lifting.

This is why a plant in a sealed jar with a healthy plant does so well while the sealed one wilts. It also explains why no water moves at all during high humidity, darkness or drought. With no evaporation there is no pull.

The Seedless Tracheophytes

Seedless tracheophytes reproduce by spores. They split into three familiar lines: ferns, horsetails, and clubmosses.

Ferns

Ferns are the seedless tracheophytes most people recognize. Their leaves are called fronds, and a young fern uncurls its fronds from a spiral, a shape called a crozier. That shape is the one in the fiddlehead you eat if you grow your own.

A fern is a seedless vascular plant with a dominant sporophyte generation — Image: Jml3, CC BY-SA 3.0, via Wikimedia Commons

Horsetails

Horsetails, genus Equisetum, are often treated as ferns. They have jointed hollow stems and a whorl of thin branches at each node, which gives them the nickname of bottlebrush. They also contain silica, which is why they are called scouring rush.

Each segment breaks off at the joint. Same vascular tissue, much simpler stem — Image: Liné1, CC BY-SA 3.0, via Wikimedia Commons

Clubmosses, and the single-vein leaf

Lycophytes are the oldest living lineage of vascular plants, and they are not ferns at all. They evolved on a separate branch. Their leaves are microphylls, which have a single unbranched vein. Almost every other vascular plant has megaphylls, leaves with a branching network of veins. One vein against many is the cleanest way to tell the two groups apart.

Lycophytes are the oldest living vascular lineage, and their leaves have one vein each — Image: Tigerente, CC BY-SA 3.0, via Wikimedia Commons

Living lycophytes are small creeping plants. Their ancestors were not. The tree-like Lepidodendron grew over 40 metres and formed the swamp forests of the Carboniferous. When those forests buried and compressed, they became coal.

The coal forests were built largely from lycophytes, close relatives of today's clubmosses — Image: Tim Bertelink, CC BY-SA 4.0, via Wikimedia Commons

Why "Seedless" Is Not a Real Group

Textbooks divide tracheophytes into seedless plants and seed-bearing plants. It is an easy split, and it is also wrong in a way that matters.

Seedless tracheophytes do not share a recent common ancestor. Ferns and horsetails are more closely related to seed plants than they are to clubmosses. On the tree of life, the clubmosses split off first, then everything else. Grouping ferns with clubmosses puts together two branches that a plant never had as a pair.

Biologists still say pteridophyte, and the International Association of Pteridologists still exists, so the term has not disappeared. But Pteridophyta is no longer accepted as a formal group. The school division is a memory aid, not a claim about ancestry.

The Seed-Bearing Tracheophytes

Seed plants, or spermatophytes, split into gymnosperms and angiosperms. The difference is simply whether the seed is enclosed.

Gymnosperms: naked seeds

Gymnosperm means naked seed, from the Greek. The seed sits on the surface of a scale or a modified leaf, usually gathered into a cone. No fruit surrounds it. Conifers are by far the largest group, with roughly 600 to 630 species. Cycads number about 338, the gnetophytes around 95 to 100, and there is exactly one ginkgo.

Cycads are palm-like but are not flowering plants, and they are not conifers — Image: Ian Alexander, CC BY-SA 3.0, via Wikimedia Commons

Ginkgo biloba is the only living species of its whole group. The fan-shaped leaf is unmistakable — Image: Eecherplaz, CC BY-SA 3.0, via Wikimedia Commons

Conifers carry both male and female cones on the same tree, and all of them are wind-pollinated. About 65 percent of gymnosperms as a whole carry separate male and female people.

Angiosperms: seeds inside fruit

Angiosperms are the flowering plants, and they are the largest group by a wide margin. Their ovules sit inside an ovary, which develops into the fruit. You are eating the seed-bearing structure whenever you eat an apple or a pea pod.

Why the Sporophyte Took Over

Tracheophytes run their lives with the sporophyte stage dominant. That is the diploid generation, with two sets of chromosomes, which produces spores. Mosses are the other way round, with the haploid gametophyte dominant.

The usual explanation is spore dispersal. A plant that grows tall holds its spores higher up, where the wind carries them further. That is only possible with a rigid, woody body that can stand up, and a rigid body needs vascular tissue to move water to its top. The two innovations pull each other along.

The Groups in One Table

Group	How it reproduces	Vascular tissue	Leaves
Clubmosses	spores	xylem and phloem	microphylls, one vein
Horsetails	spores	xylem and phloem	small and scale-like
Ferns	spores	xylem and phloem	megaphylls, branching veins
Gymnosperms	seeds, not in fruit	xylem and phloem	needles, scales, or fan-shaped
Angiosperms	seeds inside fruit	xylem and phloem	megaphylls, branching veins

Key Terms in Plain English

These are the words in this article that would send you to a dictionary. Each one is given here the way it is actually used above.

Term	What it means here
Tracheophyte	a vascular plant: one with xylem and phloem and true roots, stems and leaves
Xylem	the dead tubes that carry water and dissolved minerals up from the roots
Phloem	the living tubes that carry sugar made in the leaves to the rest of the plant
Sporophyte	the stage of the life cycle that makes spores. In a tracheophyte it is the plant you actually see
Microphyll	a leaf with a single unbranched vein, as the clubmosses have
Megaphyll	a leaf with a branching vein network, as ferns and seed plants have
Gymnosperm	a seed plant whose seeds sit unenclosed, usually on the scales of a cone
Angiosperm	a seed plant whose seeds sit inside a fruit

Terms used in this article, defined as they are used above.

Key Takeaways

• Tracheophytes are vascular plants. The name means windpipe, from the shape of the earliest conducting cells.
• They are defined by xylem and phloem, by a dominant sporophyte stage, and by true roots, stems and leaves.
• Xylem cells are dead at maturity. Phloem cells are alive. One is plumbing, the other is a living conveyor.
• Water rises by transpiration pull, not by pumping, and it costs the plant almost no energy.
• Clubmoss leaves have one vein. Nearly every other vascular plant has branching veins. That is the lycophyte split.
• Seedless tracheophytes are not one natural group. Ferns are closer to seed plants than to clubmosses.
• Gymnosperm seeds sit unenclosed, usually on cone scales. Angiosperm seeds sit inside a fruit.
• Lycophyte trees over 40 m tall built the Coal forests. Their living relatives are small creeping plants.

Frequently Asked Questions

What makes a plant a tracheophyte?

Three things: it has xylem and phloem, its dominant life stage is the sporophyte, and it has true roots, stems and leaves. Some groups have since lost one of those, but all living tracheophytes started with them.

Are ferns tracheophytes?

Yes. Ferns have both xylem and phloem, true roots and stems, and a dominant sporophyte. They reproduce by spores, which makes them seedless tracheophytes.

Why can a tree be so tall? Only a small plant gets water by diffusion?

Diffusion is too slow to lift water more than a few millimeters. Tall tracheophytes use xylem instead, and the lifting is done by evaporation at the leaves pulling on a continuous column of water molecules.

What is the difference between a microphyll and a megaphyll?

A microphyll has one unbranched vein and is found only in lycophytes. A megaphyll has a branching network of veins and is found in every other vascular plant group, from ferns to flowering plants.

Are gymnosperms still around?

Very much so. There are over 1,000 living gymnosperm species, about 600 of them conifers. Conifers dominate northern and mountain forests, and ginkgo is still grown worldwide as a street tree.

Why do older books call them "higher plants"?

Because they used to be ranked as more advanced than mosses and algae. That idea came from the scala naturae, a ladder-of-life scheme that biology abandoned. Botanists now consider the term unscientific, and it is not used.

Sources: Wikipedia articles on tracheophyte, vascular plant, xylem, phloem, vascular tissue, pteridophyte, lycophyte, fern, gymnosperm, seed plant and stoma. Images: Wikimedia Commons, with authors and licenses noted in each caption.