"Travelling" by the wind. Broadcast 11 January 1995, the first episode looks at how plants are able to move. The
bramble is an aggressive example: it advances forcefully from side to side and, once settled on its course, there is little that can stand in its way. An altogether faster species is the
birdcage plant, which inhabits
Californian sand dunes. When its location becomes exposed, it shifts at great speed to another one with the assistance of
wind – and it is this that allows many forms of vegetation to distribute their
seeds. While not a plant, the
spores of fungi are also spread in a similar fashion. One of the most successful (and intricate)
flowers to use the wind is the
dandelion, whose seeds travel with the aid of 'parachutes'. They are needed to travel miles away from their parents, who are too densely packed to allow any new arrivals.
Trees have the advantage of height to send their seeds further, and the
cottonwood is shown as a specialist in this regard. The humidity of the
tropical rainforest creates transportation problems, and the
liana-species
Alsomitra macrocarpa is one plant whose seeds are
aerodynamic 'gliders'. Some, such as those of the
sycamore, take the form of 'helicopters', while others, such as the
squirting cucumber release their seeds by 'exploding'.
Water is also a widely used method of propulsion. The tropical sea bean
Entada gigas has one of the biggest
fruits of all plants and is dispersed by water streams. However, most plants use living couriers, whether they be
dogs,
humans and other
primates,
ants or
birds, etc., and to that end, they use colour and smell to signify when they are ripe for picking.
"Growing" '' Broadcast 18 January 1995, this programme is about how plants gain their sustenance.
Sunlight is one of the essential requirements if a seed is to
germinate, and Attenborough highlights the
cheese plant as an example whose young shoots head for the nearest tree trunk and then climb to the top of the
forest canopy, developing its
leaves en route. Using sunshine,
air, water and a few
minerals, the leaves are, in effect, the "factories" that produce food. However, some, such as the
begonia, can thrive without much light. To gain moisture, plants typically use their
roots to probe underground. Trees pump water up pipes that run inside their trunks, and Attenborough observes that a sycamore can do this at the rate of 450 litres an hour – in total silence. Too much rainfall can clog up a leaf's
pores, and many have specially designed 'gutters' to cope with it. However, their biggest threat is from animals, and some require extreme methods of defence, such as
spines,
camouflage, or
poison. Some can move quickly to deter predators: the
mimosa can fold its leaves instantly when touched, and the
Venus flytrap eats insects by closing its leaves around its prey when triggered. Another carnivorous plant is the
trumpet pitcher that snares insects when they fall into its tubular leaves. Attenborough visits
Borneo to see the largest pitcher of them all,
Nepenthes rajah, whose traps contain up to two litres of water and have been known to kill small
rodents.
"Flowering" Broadcast 25 January 1995, the next installment is devoted to the ways in which plants reproduce.
Pollen and a
stigma are the two components needed for fertilisation. Most plants carry both these within their flowers and rely on animals to transport the pollen from one to the stigma of another. To do this, they attract their couriers with colour, scent and
nectar. It isn't just
birds that help
pollination: some
mammals and
reptiles also do so. However, it is mostly
insects that are recruited to carry out the task. To ensure that pollen is not wasted by being delivered to the wrong flower, some species of plant have developed exclusive relationships with their visitors, and the
gentian and its attendant
carpenter bees is one example. Since pollen can be expensive to produce in terms of
calories, some plants, such as
orchids, ration it by means of
pollinia and a strategically placed landing platform. Other orchids offer no reward for pollination, but instead mislead their guests by mimicking their markings and aroma, thus enticing males to 'mate' with them (
Pseudocopulation). The most extreme fertilisation method is one of imprisonment, and one plant that uses it is the
dead horse arum. It is often found near gull colonies, and mimics the appearance and smell of rotting flesh.
Blow-flies are attracted to it, and are forced to stay the night before being allowed to depart in the morning, laden with pollen. Finally, Attenborough introduces the world's largest
inflorescence: that of the
titan arum.
"The Social Struggle" Broadcast 1 February 1995, this episode examines how plants either share environments harmoniously or compete for dominance within them. Attenborough highlights the
1987 storm and the devastation it caused. However, for some species, it was that opportunity for which they had lain dormant for many years. The space left by uprooted trees is soon filled by others who move relatively swiftly towards the light. The
oak is one of the strongest and longest-lived, and other, lesser plants nearby must wait until the
spring to flourish before the light above is extinguished by leaves. Tropical forests are green throughout the year, so brute force is needed for a successful climb to the top of the canopy: the
rattan is an example that has the longest stem of any plant. As its name suggests, the
strangler fig 'throttles' its host by growing around it and cutting off essential water and light. Some can take advantage of a fallen tree by setting down roots on the now horizontal trunk and getting nutriment from the surrounding
moss and the fungi on the dead
bark. The mountain ash (
eucalyptus regnans) grows so tall, that regeneration becomes a considerable problem. It is easily flammable, so its solution is to shed its seeds during a
forest fire and sacrifice itself. It therefore relies on the periodic near-destruction of its surroundings in order to survive. Attenborough observes that catastrophes such as fire and
drought, while initially detrimental to wildlife, eventually allow for deserted habitats to be reborn.
"Living Together" Broadcast 8 February 1995, the fifth programme explores the
alliances formed between the animal and plant worlds. Attenborough dives into
Australia's
Great Barrier Reef and contrasts the nocturnal feeding of
coral, on microscopic creatures, with its daytime diet of
algae. Some
acacias are protected by
ants, which will defend their refuge from any predator. Besides accommodation, the guards are rewarded with nectar and, from certain species,
protein for their
larvae as well. Fungi feed on plants but can also provide essential nutriment to saplings (
Mycorrhiza). The connection is never broken throughout a tree's life and a quarter of the sugars and starches produced in its leaves is channelled back to its fungal partners. Meanwhile, fungi that feed on dead wood leave a hollow trunk, which also benefits the tree. Orchids enjoy a similar affiliation.
Lichens are the product of a relationship between fungi and a photosynthetic associate, usually algae. They are extremely slow-growing, and a
graveyard is the perfect location to discover their exact longevity.
Mistletoe is a
hemiparasite that obtains its moisture from a host tree, while using own leaves to manufacture food. Its seeds are deposited on another by the
mistletoe tyrannulet, following digestion of the fruit. The dodder (
Cuscuta) is also parasitic, generally favouring
nettles, and siphons its nourishment through periodic 'plugs' along its stem. The
rafflesia has no stem or leaves and only emerges from its host in order to bloom – and it produces the largest single flower: one metre across.
"Surviving" in Arizona. Broadcast 15 February 1995, the final episode deals with plants that live in hostile environments. Attenborough visits
Ellesmere Island, north of the
Arctic Circle, to demonstrate that even in a place that is unconducive to life, it can be found. Algae and lichens grow in or on
rock, and during summer, when the ice melts, flowers are much more apparent. However, they must remain close to the ground to stay out of the chilling
wind. In the
Tasmanian mountains, plants conserve heat by growing into 'cushions' that act as
solar panels, with as many as a million individual shoots grouped together as one. Others, such as the
lobelia in
Mount Kenya, have a 'fur coat' of dense hairs on their leaves. The
saguaro cactus in the
Sonoran Desert flourishes because of its ability to retain vast amounts of water, which can't be lost through leaves because it has none. Many desert dwellers benefit from an accelerated life cycle, blooming rapidly within weeks after rainfall. Conversely,
Mount Roraima is one of the wettest places on Earth. It is a huge
sandstone plateau with high
waterfalls and nutrients are continuously washed away, so plants have to adapt their diet if they are to survive. A
bladderwort is shown invading a
bromeliad. Inhabitants of
lakes have other problems to contend with: those that dominate the surface will proliferate, and the
Amazon water lily provides an apt illustration. Attenborough ends the series with an entreaty for the conservation of plant species. == DVD and book ==