CHAPTER ONE
THE STORY OF PLANTS & FLOWERS
OUR BOTANICAL WORLD The story of plants and flowers is an enduring tale of Earth-changing events, extraordinary evolution and ultimate survival. Although humans have only been part of this narrative for the slimmest chapter of time, we owe much to the wonders of the botanical world – not least the oxygen that gives us life.
Stop and look around you. Somewhere in your vicinity there will be a plant or flower: a prized bloom, a beautiful wildflower, a lowly patch of moss, a potentially troublesome weed, a treasured houseplant, a towering tree or perhaps a plant-inspired design. Now stop and take a deep breath. It’s easy to take for granted the oxygen that we inhale, but don’t forget that it comes from somewhere – or indeed, from nearly 400,000 different known species that make up the Kingdom Plantae. The story of the plants on Earth spans Great Oxygenation Events, eras of extreme evolution, mass extinctions, divided kingdoms, powerful pollinators and the evolution of modern humans (Homo sapiens). But while the Animal Kingdom developed from the same eukaryotic, membrane-bound organisms as plants (at least 1.8 billion years ago – see page 24), it would be millions of years before humans were bipedal and brainy enough to quite literally stand up and ‘smell the roses’. By the advent of anatomically modern humans – estimated between 200,000 and 100,000 BCE – the Plant Kingdom had well and truly conquered the Earth. Thanks in part to a ‘Big Bloom’ of reproductively advanced flowering plants at least 140 million years ago (see page 41), biomes around the world were infiltrated by one promiscuous bloom or another, and thus were forever changed. The world of the first Homo sapiens had forests to roam in, fruits and seeds to eat, leaves to provide shelter, wood to carve and build with, herbs to heal
and myriad plant species to inspire wonder, invention and creativity. By at least 10,000 BCE, the story of plants and flowers was also one of plants and people (see page 58), beginning with humanity’s first foray into forest gardening, the precursor of agriculture and cultivation. By 3000 BCE, we were sharing our botanical knowledge through writing. By 1500 BCE, evidence from Egypt shows that we had developed systems of ornamental horticulture (see page 60). By this point in history, humans were actively harnessing the pleasure-enhancing powers of the botanical world, either for their aesthetic appeal or to be used to benefit our health, wellbeing and happiness. We were Gardening for Purpose (see page 64) and Gardening for Pleasure (see page 68). A thousand years later, around 340 BCE, the great Greek philosopher Aristotle established the first botanical gardens in Athens, in part prompting his student Theophrastus to compile his pioneering Historia Plantarum or ‘Enquiry into Plants’ (see page 62). This seminal text laid the foundations for a wealth of discovery to come – the amazing, unfurling, eternal discovery of our botanical world. Just 3.8 billion years since Planet Earth’s very first cellular life, the story of plants and flowers continues, and this chapter follows, exploring the realms of the Plant Kingdom, the biomes it helps create and the people who have interacted with it through millennia of plant-inspired existence. Opposite The genome sequence of Amborella trichopoda, a rare tropical tree endemic to New Caledonia, has revealed it to be the sole survivor of the oldest line of flowering plants.
22
COLLINS BOTANICAL BIBLE
PATHWAYS OF THE PLANT KINGDOM CYANOBACTERIA Photosynthesises to produce oxygen SINGLE-CELLED ORGANISMS Archaea and Bacteria
EUKARYOTES Cells with membrane-bound nucleus
GREEN-BLUE ALGAE Glaucophytes
ANIMAL KINGDOM Kingdom Animalia
THE PLANT KINGDOM Kingdom Plantae
RED & BROWN ALGAE Rhodophyta & Phaeophyta
FUNGI KINGDOM Kingdom Fungi
ANCESTRAL GREEN ALGAE Streptophyta LAND PLANTS Embryophytes
GREEN ALGAE Chlorophyta & Charophyta
LIVERWORTS Marchantiophyta
VASCULAR LAND PLANTS Trachaeophytes
NON-VASCULAR LAND PLANTS Bryophytes MOSSES Bryophyta
HORNWORTS Anthocerotophyta
SPORE-PRODUCING PLANTS Pteridophytes CLUB MOSSES Lycopodiophyta
FERNS Pteridophyta
HORSETAILS Equisetophyta
SEED-PRODUCING PLANTS Spermatophytes
NON-FLOWERING SEED PLANTS Gymnosperms CONIFERS Pinophyta
CYCADS Cycadophyta
ONE SEED LEAF & ONE-APERTURE POLLEN Monocots
GINKGO Ginkgophyta
TWO SEED LEAVES & TRICOLPATE POLLEN Eudicots
DIVERGED FROM DEVELOPMENT OF OTHER FLOWERING PLANTS
Magnoliids
24
COLLINS BOTANICAL BIBLE
FLOWERING PLANTS Angiosperms
Basal Angiosperms
PATHWAYS OF THE PLANT KINGDOM
Where do pineapples come from? How are humans related to plants? Make the connection between the evolutionary wonders of the Plant Kingdom – within itself and in relation to other divergent life forms – and everything is illuminated.
Pick a plant, any plant.Your favourite houseplant or a plant derivative such as a coconut. Think about where that plant came from and how it got here. How is it connected to the lavender bush in your garden or the giant redwoods you long to visit one day, and how is it connected to you – a walking, talking, plant-curious Homo sapiens? This chapter attempts to put these questions into context, via a journey from the first single-celled organisms that appeared some 3.8 billion years ago to the botanical world as we experience it today: currently the greatest biomass on Earth, comprising 400,000 known plant species and collectively providing the structural canvas and oxygen for a huge diversity of other life forms. This monumental journey, illustrated opposite by Lynn Hatzius (see page 373), traces the route of the earliest oxygenproducing cyanobacteria (see page 27) to the first eukaryotes from which algae, plants, fungi and animals (including humans) would evolve. Then it’s Viridiplantae (green plants) all the way, in all their verdant glory. Ancestral green algae evolved into new and more complex forms of aquatic green algae, some cells found a way to exist on dry land and developed into land plants (see page 28). Some land plants then diverged into liverworts, hornworts and mosses (see pages 30–31),
while others developed vascular tissues to help transport food, water and products of photosynthesis (see page 111). Vascular plants spawned enormous diversity, branching off into sporeproducing plants – the club mosses, horsetails and ferns (see pages 34–35) – before evolving into seed producers (see page 36). The first seed producers emerged around 380 million years ago, divided into groups of non-flowering plants or gymnosperms (see page 37) – conifers, cycads, gnetophytes and ginkgo (see pages 38–39) – and flowering plants or angiosperms (see page 40), which make up an estimated 90 per cent of the known Plant Kingdom today. Of these, 20 per cent are known as monocots (see page 42), 75 per cent are known as eudicots (see page 45), and a few thousand refuse to be typecast quite so neatly. These are currently split between the magnoliids (see page 46) and the basal angiosperms (see page 49). Looking more closely at how the Plant Kingdom most likely evolved (even with the proviso that 30 per cent of all estimated plant species are yet to be discovered and any assumed evolutionary ‘pathway’ could reroute at any point) can be a wonderfully revealing experience, not least for the reminder of just how intrinsically connected plants and people really are.
Opposite Explore the amazing diversity of the Plant Kingdom further in the pages to follow, or turn to page 58 for more on the deep connection between plants and people.
THE THE STORY STORY OF OF PLANTS PLANTS && FLOWERS FLOWERS 25
FLOWERING PLANTS Flowering plants, or angiosperms, from obvious flowers to cacti to huge trees, make up around 90 per cent of the Plant Kingdom and include monocots, eudicots, magnoliids and basal angiosperms. The key to the huge diversity of flowering plant species known today – over 369,000 and counting – lies in their highly evolved reproductive systems. They have enclosed ovules, a wide array of pollination techniques, numerous ways to attract pollinators and an impressive ensemble of seed-dispersal methods, which in turn gives us much of our food.
40
COLLINS BOTANICAL BIBLE
FLOWERING PLANTS
The Big Bloom
F
lowers provide much of the natural beauty in our botanical world but they are worth so much more than that. For most people, the word ‘flower’ conjures up images of brightly coloured petals or induces scent-related nostalgia: bright yellow sunflowers, red roses or jasmine on a warm night. In fact, flowering plants are wildly diverse and their number includes a range of perhaps unexpected members, too: the majority of deciduous trees; all cacti, succulents and grasses; many of our favourite houseplants; and a large proportion of our food. In these angiosperms, the ‘flowering’ part of the plant is not quite so obvious. So what is a flower? Botanically speaking, it refers to the reproductive organs of a large number of the world’s seed-bearing plants – more than 369,000 of all known plant species, to put things in context. The function of the flower is to effect reproduction via its various floral parts (see chapter 2 for more details of plant and flower anatomy and function). Stereotypically, this involves whorls of green sepals, pollinator-attracting petals, pollen-producing stamens and carpels, each with a style, a stigma and an egg-producing ovary. The word stereotypical is key, as flowering plant species actually show a wide variation in floral structure. In some, petals are greatly reduced or lost altogether, in others the sepals are colourful and petal-like. Flower parts can be fused together or symmetrical, have a reduced stalk or cluster together in what’s known as an inflorescence. Some plants, such as sunflowers or daisies, have flower heads that are made up of many small flowers. Other plants have protracted life cycles and produce flowers at long intervals. Tahina spectabilis, or Madagascar palm, grows to huge proportions, dies after fruiting and flowers only once – after 100 years. Puya rainmondii, or Queen of the Andes, takes 80 to 150 years to bloom. Sometimes the most distinctive part of a flowering plant is its fruit, for example, pineapple, acorn or peanut. All these features are extremely helpful to botanists in terms of sorting flowering plants into their family, genus and species. Opposite The dramatic Cattleya labiata (ruby-lipped cattleya), of the family Orchidaceae, dominates a lush junglescape in Martin Johnson Heade’s Orchid and Hummingbird near a Waterfall (1902).
March of the flowers So when did flowers first appear? The great naturalist Charles Darwin called it an ‘abominable mystery’, but a patchwork of fossil and genetic evidence provides an increasing number of clues. A recent study into the DNA of known plant species suggests that a small, woody ‘living fossil’ called Amborella trichopoda (see page 23), found only on the South Pacific island of New Caledonia, has a lineage that goes back 130 million years. The oldest fossilised flower specimen also dates back to this time. Many early flower fossils, however, appear unrelated to any modern flowering plant family. A recent find in China, a genus known as Archaefructus, supports the theory that the first flowers were not showy, but simple and inconspicuous. While a 2017 study using fossil and genetic data of past and present flowering plants resulted in a 3D model of ‘the first flower’, a 140million-year-old magnolia-like species. Short, rapid life cycles may have also helped early bloomers to seed new ground and thus evolve faster than their competitors, the spore producers and non-flowering seed plants. What definitely did create an advantage for flowering plants was their approach to pollination. Wind was too hit-and-miss; insects could do a much more efficient job. The question was: how to attract them? Research suggests that it took another 30 to 40 million years before flowers had evolved sufficiently to flaunt anything like a flashy petal at a passing insect, but once they did, they sparked a ‘great radiation’ of diversity. Thus flowers evolved to include bright colours and irresistible scent in their quest for pollination. The sweet, nutritious liquid that they produced lured the ancestors of bees, butterflies and wasps onto their pollen-topped stamens and waiting stigmas. If a match was made, the ovule would be fertilised and mature into a seed complete with an embryo – the part that would grow into a new plant upon germination – and, in most cases, a nutritious endosperm to help feed it. When flowers developed the ability to cross-pollinate between the flowers of different plants of the same species, rather than flowers on the same plant, their gene pool became stronger and their dominance in the Plant Kingdom was secured.
THE STORY OF PLANTS & FLOWERS
41
GARDENING FOR PLEASURE
The garden as muse
T
he botanical world has served as a source of inspiration for millennia, as have the earthly paradises that men and women have continually sought to create. ‘I perhaps owe having become a painter to flowers,’ said the French Impressionist Claude Monet (1840–1926) who created his own slice of Eden at Giverny, renowned for inspiring monumental works such as his Water Lilies series (see page 345). Indeed, Monet was just one of an array of gardenloving artists of the late nineteenth-century Impressionist era, including the Spanish artist Joaquín Sorolla, who created his horticultural muse in Madrid, inspired by Islamic gardens such as the Alhambra in Granada, and fellow Frenchman Pierre Bonnard, who was heavily influenced by leading English garden designers of the period, William Robinson and Gertrude Jekyll. Both Monet and Bonnard’s gardens appeared to run wild and free, as did the principles of Robinson’s seminal text The Wild Garden (1870), which favoured loose drifts of colour over notions of formality. Bonnard’s ‘jardin sauvage’ at Vernonnet is very much captured in his landscape-esque artwork Resting in the Garden (1914), and such horticultural ideals were soon assimilated into the gardens and public spaces of a newly industrialised America. Frida Kahlo’s garden (see page 348) at the Casa Azul in Mexico City was also an undeniable muse displaying the same native species and colours in pots and flowerbeds as found in her paintings and hair. While the artist and architect César Manrique pretty much took a whole island as his plot, working his sympathetic building designs, murals and planting schemes into the volcanic terrain of the Canary island of Lanzarote – his terraced Jardín de Cactus is particularly inspiring, with more than 10,000 different plants selected by eminent botanist Estanislao González Ferrer. Over in Marrakech, the Jardin Majorelle is a similar riot of vibrant colour and exotica that took the painter Jacques Majorelle (1886–1962) 40 years to create, a lifelong devotion to plants and art echoed by Derek Jarman’s garden at Dungeness, Barbara Hepworth’s fern-strewn studio in Cornwall and William Morris’s garden at Red House. Richard Mabey’s wonderful book, The Cabaret of Plants (2015), also reminds us that plants themselves are the principal source of inspiration when creating a
70
COLLINS BOTANICAL BIBLE
garden – the garden being a space in which we best present plants and potentially manifest our creative urges.It opens with illustrations of what may be the first human representations of plants in cave art some 35,000 years ago, before meandering through various encounters between plants and people, including whole chapters riffing on the favoured flowers of Romantic poets, such as William Wordsworth and John Keats. Tucked within the pages of Mabey’s ‘cabaret’ also lies an image of a gigantic Victoria amazonica water lily leaf, the extraordinary natural engineering of which inspired the metal framework of the Crystal Palace that housed Britain’s Great Exhibition of 1851. As Mabey attests: ‘No large building had ever been built like this chimera of steel and cellulose before, but every large glass building since ultimately derives from it.’ A roll call of inspired gardeners throughout history – among them artists, designers, scientists, politicians and, of course, gardeners – displays similarly epic proportions, from the great naturalist Charles Darwin who wrote On the Origin of Species (1859) in a study overlooking his garden at Down House, to American Founding Father Thomas Jefferson who wandered through his extensively experimental gardens at Monticello,Virginia, before drafting America’s Declaration of Independence in 1776. The garden was also an obvious muse for many of history’s most famous botanists, from Carl Linnaeus who worked out his idea for binomial nomenclature (see page 123) during his directorship of Uppsala’s botanic gardens in Sweden, to English naturalist John Ray, who conducted his taxonomic and botanical experiments in the university gardens of Cambridge. Possibly the most a-musing garden happening of all, however, may be the day that a young scientist by the name of Isaac Newton was allegedly hit on the head by an apple. The fruit in question fell from a Flower of Kent tree (Malus pumila) in his family’s garden at Woolsthorpe Manor, Lincolnshire, thus taking things to another dimension – it inspired the theory of gravity.
Opposite The gardens at Claude Monet’s Giverny spill over with the colours, fragrance, glorious nature and light that so obviously inspired his paintings, and kept him rooted even during the artillery fire of World War I.
‘I must have f lowers, always and always.’ Claude Monet, French artist (1840–1926)
THE STORY OF PLANTS & FLOWERS
71