How Plants Work: Form, Diversity, Survival

1094 Pages·2018·173.46 MB·English

by  Stephen Blackmore

HOW PLANTS WORK
Form, Diversity, Survival
CONSULTANT EDITOR Stephen Blackmore
WITH A FOREWORD By Peter Crane
Contents
Foreword by Peter Crane FRS
Editor’s preface: the world of plants
1 An introduction to plant morphology
2 Roots
3 Stems
4 Leaves
5 Plant reproduction
6 Cones and flowers
7 Seeds and fruits
8 People and plants
Glossary
Further reading
Index
Acknowledgements
Picture credits
Foreword
Peter Crane FRS
Plants are the foundation of human existence. They are our indispensible
companions on this singular planet in the vastness of space. Our species evolved
against a changing backdrop of forests and grasslands, and our bodies are shaped
by millions of years of interactions with plants. Today, plants remain the
ultimate source of all the chemical energy on which our day-to-day existence
depends. And make no mistake, the present and future of all of humanity
depends on the continuing miracle of photosynthesis, which provides food for us
all.
Yet plants, with no voice of their own, are easy to take for granted. The direct
connections between people and plants that once shaped all human lives are now
obscured by the rise of modernity. Our specialized lifestyles push plants to the
background, and with more than half of all people now living in cities, the lives
of plants can seem increasingly remote.
This fascinating and richly illustrated book reintroduces us to the world of
plants and the intricacies of their existence, including how they live, grow and
reproduce. It is an intimate, close-up portrait that deepens our understanding of
the commonplace and the exotic. At the same time, it reveals the beauty of plants
in new ways. The diversity of plants is brought to life through exemplars that
engage, and through insights that enrich. To borrow a phrase from Darwin, there
is grandeur in this view of plants. I am sure you will enjoy it.
Even the smallest plants appear striking when highly magnified. The most widespread form of the common
liverwort (Marchantia polymorpha ssp. ruderalis), found in man-made or disturbed habitats, has colourful
scales that provide protection to its growing tips.
The foliage of ferns grows and unfurls in a characteristic shape, called a ‘crozier’ because of its resemblance to
the head of the staff carried as a symbol of office by a bishop. The small scales covering its surface provide
protection as the frond grows.
Editor’s preface: the world of plants
A
mid the hustle and bustle of our fast-paced lives, an everyday miracle
is happening all around us, often unnoticed. Plants are working their silent
and unobtrusive magic – capturing the energy of the sun and powering life
on Earth. At first glance, plants rarely seem to be doing anything at all,
perhaps just swaying gently in the breeze. But look more closely, as this
book does, and we soon discover that plants are hard at work. Absorbing
minerals and water from the soil and carbon dioxide from the air, they are
creating themselves, fuelling their growth with the products of
photosynthesis.
Flowerheads of purple salsify (Tragopogon porrifolius) open only to expose their bright orange pollen in the
morning and then close in the early afternoon.
The wonder of photosynthesis
This remarkable process, which creates carbohydrates and oxygen, began
billions of years ago in the first single-celled marine algae. It made the oceans
and then the atmosphere rich in oxygen, setting the stage for the evolution of
millions of species of animals, including our own. Animals and plants face the
same challenges: the need for food or a source of energy, and the need for a safe
place in which to live and reproduce. Being solar powered, plants have solved
the energy problem but, unlike animals, they must tackle the other challenges
without moving from the spot they are rooted to.
By many ingenious devices, they have clearly succeeded. There are more than
400,000 species of plants, with more being discovered every year, and they have
spread everywhere on Earth where water is freely available. Only the driest
deserts, and the permanently frozen polar regions and highest mountains, are
devoid of vegetation. The diversity of vegetation is enormous – from tropical
rainforests to savannah, boreal forests, tundra, mangrove swamps and alpine
meadows – and it shapes and defines the landscapes of our planet. Our world is
full of life because it is green.
This book is an exploration of how plants have diversified through time, from
the dawn of life on land, and how they have become adapted for survival in a
thousand and one different forms. It examines the microscopic and the short-
lived, right up to the giant redwoods (Sequoiadendron giganteum), thousands of
years old and the largest living things our planet has ever known. Starting with
the story of plant evolution, we explore plants organ by organ to understand the
ways in which their internal anatomy and external form are fine-tuned solutions
to physical and biological challenges.
The leaves of tropical pitcher plants (Nepenthes spp.) have highly modified tips, which form liquid-filled traps
containing enzymes to capture and digest insects.
The life of roots is revealed as a dynamic interaction between the plant and
the physical environment of soil and rock. This goes far beyond simply
anchoring the plant and absorbing water. A host of biological interactions are
hidden from sight: some roots partner with fungi, which help them to absorb
nutrients from the soil; others harness the ability of bacteria to capture nitrogen
from the air to enrich the soil they grow in. Moving upwards, stems raise plants
higher towards the light, and branch, with complex architecture, to increase the
area exposed to light. Specialized cells and tissues allow water to be transported
to the tips of the highest trees, and sugars to be moved upwards or downwards
between the leaves and the root system. The leaf is the fundamental powerhouse