---
title: "Plants Without Seeds"
book: "Primary & Middle School Biology"
subject: biology
language: en
chapter: 24
exercises: 11
source: https://one-course.com/books/biology/1/en/chapter/24-plants-without-seeds
---

# Chapter 24 — Plants Without Seeds

The shady side of the old wall is upholstered in moss; under the beech trees, [ferns](#prop-g4-plants-without-seeds-damp) unroll their great green fronds. Search them all summer: you will find no [flower](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#def-g3-flowers-fruits-seeds-parts), no [fruit](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform), no [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) — ever. Yet moss and [ferns](#prop-g4-plants-without-seeds-damp) spread perfectly well. [Plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant), it turns out, have more than one way of making the next generation.

## 24.1 Ferns and mosses: reproduction by spores

**Definition 24.1 (Spore).**

A *spore* is a microscopic grain, made in enormous numbers, from which a new [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) can grow. Unlike a [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) ([Definition 9.1](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed)), a spore is a single speck with *no [food store](https://one-course.com/books/biology/1/en/chapter/20-animals-through-the-seasons#def-g3-animals-through-seasons-active) and no ready-made tiny [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) inside* — it is a beginning at its barest.

**Example 24.2 (Under the fern’s fronds).**

Turn a fern frond over in late summer: neat rows of brown dots line its underside. Each dot is a packet of thousands of [spores](#def-g4-plants-without-seeds-spore); ripe, the packets split, and the [spores](#def-g4-plants-without-seeds-spore) drift off on the air like the finest dust. A [spore](#def-g4-plants-without-seeds-spore) landing on damp shaded ground can grow — by stages — into a new fern.

![Under the frond: the neat rows of brown dots, each one a packet of thousands of spores.](https://one-course.com/images/onecourse/chapters/biology-1/g4-plants-without-seeds/img-e447ca1f41f8.jpg)

*Under the frond: the neat rows of brown dots, each one a packet of thousands of [spores](#def-g4-plants-without-seeds-spore).*

**Proposition 24.3 (Spore plants need dampness).**

[Spore](#def-g4-plants-without-seeds-spore) [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) — *mosses* and *ferns* — can only reproduce where it is *damp*: their [spores](#def-g4-plants-without-seeds-spore), and the delicate stages that grow from them, dry out and die in dry air. That is why moss carpets the shaded north wall but never the sunny south one, and why [ferns](#prop-g4-plants-without-seeds-damp) crowd damp woods, stream banks and wells.

**Proof.** *Admitted at this level.* ∎

**Remark 24.4 (A spore is not a seed).**

Both are beginnings that travel, but the [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) is a survival kit — coat, [food store](https://one-course.com/books/biology/1/en/chapter/20-animals-through-the-seasons#def-g3-animals-through-seasons-active), ready-made plantlet — while the [spore](#def-g4-plants-without-seeds-spore) is bare. Hence the numbers: the fern’s millions of [spores](#def-g4-plants-without-seeds-spore) against the bean pod’s dozen [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform). Bare beginnings are cheap to make and easy to lose; the two plans echo the codfish and the elephant of [Proposition 23.7](https://one-course.com/books/biology/1/en/chapter/23-how-animals-reproduce#prop-g4-animal-reproduction-strategies).

## 24.2 New plants without any sowing

**Definition 24.5 (Vegetative reproduction).**

Many [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) can also make new [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) *directly from a piece of themselves* — no [spores](#def-g4-plants-without-seeds-spore), no [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform), one parent only. This is *vegetative reproduction*. The new [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) is a living continuation of the old one, and resembles it exactly.

**Example 24.6 (The strawberry’s runners).**

A strawberry [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) sends out long thin horizontal [stems](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) — *runners* — across the soil. Where a runner touches down, it [roots](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts), sprouts [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts), and becomes a complete new strawberry [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant); the runner then withers, and the child stands free. One [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) becomes a patch without a single [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) sown.

**Example 24.7 (Bulbs and tubers).**

The tulip *bulb* and the potato *tuber* are underground storerooms — and starting kits. Left in the ground, a [bulb](#ex-g4-plants-without-seeds-bulbtuber) splits into daughter [bulbs](#ex-g4-plants-without-seeds-bulbtuber), each a future tulip; every “[eye](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense)” of a sprouting potato can grow into a whole new [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant). Gardeners [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) potatoes, not potato [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform).

**Method 24.8 (Taking a cutting).**

Gardeners copy [vegetative reproduction](#def-g4-plants-without-seeds-vegetative) with *cuttings*:

1. cut a healthy young shoot, a hand’s length, from the parent [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) (mint, willow and geraniums work well);
2. remove the lower [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) and stand the shoot in water or moist soil;
3. wait: in days or weeks, [roots](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) grow from the cut [stem](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) ;
4. [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) it out — a complete new [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) , identical to its one parent.

**Remark 24.9 (One parent, exact copies).**

[Seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform) mix two parents ([Remark 23.3](https://one-course.com/books/biology/1/en/chapter/23-how-animals-reproduce#rem-g4-animal-reproduction-mix) holds for [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) too, via [pollen](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#def-g3-flowers-fruits-seeds-parts)); [vegetative reproduction](#def-g4-plants-without-seeds-vegetative) copies one. That is why every [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) of a named apple variety is grown from [cuttings](#met-g4-plants-without-seeds-cutting) and grafts, never from pips: the orchard wants exact copies of one excellent tree. The price of copying is sameness — an orchard of identical trees shares identical weaknesses, as a later year will show.

## 24.3 Exercises

**Exercise 24.1 ★.**

Name two [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) that never make [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform). How do they reproduce?

**Solution of Exercise 24.1.**

[Mosses](#prop-g4-plants-without-seeds-damp) and [ferns](#prop-g4-plants-without-seeds-damp). They reproduce by [spores](#def-g4-plants-without-seeds-spore) — microscopic grains released in enormous numbers.

**Exercise 24.2 ★.**

Give two differences between a [spore](#def-g4-plants-without-seeds-spore) and a [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed).

**Solution of Exercise 24.2.**

A [spore](#def-g4-plants-without-seeds-spore) is microscopic and bare — no [food store](https://one-course.com/books/biology/1/en/chapter/20-animals-through-the-seasons#def-g3-animals-through-seasons-active), no ready-made tiny [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant); a [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) carries both, inside a protective coat. And [spores](#def-g4-plants-without-seeds-spore) are made by the million, [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform) by the dozen.

**Exercise 24.3 ★.**

Where are the fern’s [spores](#def-g4-plants-without-seeds-spore) made? Describe what you find under a frond in late summer.

**Solution of Exercise 24.3.**

On the underside of the fronds: neat rows of brown dots, each a packet of thousands of [spores](#def-g4-plants-without-seeds-spore) that split open when ripe and let them drift off like dust.

**Exercise 24.4 ★.**

Why does moss grow on the shaded north wall and not the sunny south one?

**Solution of Exercise 24.4.**

Moss reproduces by [spores](#def-g4-plants-without-seeds-spore), and [spores](#def-g4-plants-without-seeds-spore) and their delicate young stages need dampness — they dry out and die in dry air. The shaded north wall stays damp; the sunny south wall bakes.

**Exercise 24.5 ★.**

What is [vegetative reproduction](#def-g4-plants-without-seeds-vegetative)? How many parents does it take?

**Solution of Exercise 24.5.**

Making a new [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) directly from a piece of the parent [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) — runner, [bulb](#ex-g4-plants-without-seeds-bulbtuber), [tuber](#ex-g4-plants-without-seeds-bulbtuber), cutting. One parent only.

**Exercise 24.6 ★.**

Tell the story of a strawberry runner, from first [stem](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) to free-standing child [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant).

**Solution of Exercise 24.6.**

The [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) sends a long thin [stem](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) — the runner — across the soil; where it touches down it [roots](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) and sprouts [leaves](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts), becoming a complete little [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant); the runner then withers and the child stands free, identical to its parent.

**Exercise 24.7 ★.**

Why do gardeners [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) potatoes rather than sow potato [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform)? What can each “[eye](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense)” do?

**Solution of Exercise 24.7.**

A planted potato (a [tuber](#ex-g4-plants-without-seeds-bulbtuber)) sprouts reliably from its “[eyes](https://one-course.com/books/biology/1/en/chapter/5-the-five-senses#def-g1-the-five-senses-sense)”, each of which can grow into a whole [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) identical to the good variety planted — faster and surer than [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform).

**Exercise 24.8 ★.**

Try it: take a mint cutting by [Method 24.8](#met-g4-plants-without-seeds-cutting) and stand it in a glass of water on the windowsill. What appears, and after roughly how long?

**Solution of Exercise 24.8.**

Open answer. White [roots](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts) appear from the submerged [stem](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-parts), typically after one to two weeks; the cutting is then ready to [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) — a complete new mint, from one parent.

**Exercise 24.9 ★★.**

The fern makes millions of [spores](#def-g4-plants-without-seeds-spore); the bean pod, a dozen [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform). Explain the difference in numbers with [Remark 24.4](#rem-g4-plants-without-seeds-sporeseed) — and name the [animal](https://one-course.com/books/biology/1/en/chapter/2-animals-around-us#def-g1-animals-around-us-animal) pair whose strategies they echo.

**Solution of Exercise 24.9.**

The [spore](#def-g4-plants-without-seeds-spore) is bare and cheap: without [food store](https://one-course.com/books/biology/1/en/chapter/20-animals-through-the-seasons#def-g3-animals-through-seasons-active) or plantlet, almost every one is lost, so millions must be made. The [seed](https://one-course.com/books/biology/1/en/chapter/9-from-seed-to-plant#def-g2-from-seed-to-plant-seed) is an expensive survival kit, so a dozen well-equipped ones suffice. They echo the codfish (millions, uncared for) and the elephant (few, well provided).

**Exercise 24.10 ★★.**

A gardener finds the new strawberry [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) identical to the parent, while her bean [plants](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) vary a little from their parents. Explain both observations with [Remark 24.9](#rem-g4-plants-without-seeds-copy).

**Solution of Exercise 24.10.**

The strawberries came by runner — [vegetative reproduction](#def-g4-plants-without-seeds-vegetative), one parent, exact copies. The beans came from [seeds](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#prop-g3-flowers-fruits-seeds-transform) made by [flowers](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#def-g3-flowers-fruits-seeds-parts), mixing two parents’ contributions ([pollen](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#def-g3-flowers-fruits-seeds-parts) from one [flower](https://one-course.com/books/biology/1/en/chapter/16-flowers-fruits-and-seeds#def-g3-flowers-fruits-seeds-parts), [egg cells](https://one-course.com/books/biology/1/en/chapter/23-how-animals-reproduce#def-g4-animal-reproduction-sexual) in another), so each bean [plant](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-plant) varies a little.

**Exercise 24.11 ★★★.**

A willow [branch](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) snapped off by a winter flood, carried downstream and stranded on a mud bank, often grows into a new willow tree. Which kind of reproduction is this — and why are rivers so often lined with willows? What did the flood do that the gardener of [Method 24.8](#met-g4-plants-without-seeds-cutting) does with scissors?

**Solution of Exercise 24.11.**

[Vegetative reproduction](#def-g4-plants-without-seeds-vegetative) — the [branch](https://one-course.com/books/biology/1/en/chapter/3-plants-around-us#def-g1-plants-around-us-tree) is a natural cutting. The flood did the gardener’s scissor-work: it cut the shoot, carried it, and planted it in wet mud, willow’s ideal rooting bed. Rivers line themselves with willows by breaking and planting them in the same stroke.