These extraordinary plants are the ultimate survivors

Desert Mistletoe

Any ideas of kissing under white berries need to be put aside as there’s nothing romantic about this tough survivor. Desert mistletoe is a hemiparasite, which means that – like most plants – they use a process called photosynthesis to create nourishment from sunlight, carbon dioxide and water. However, it also steals extra nutrients and water from the host trees and shrubs upon which it grows. Buckthorn, mesquite, and ironwood trees are often prey to the desert mistletoe, which secures new hosts through the dispersal of its sticky seeds. The seeds are eaten by birds who also end up with some stuck to their feet and beaks. Through cleaning themselves by wiping the seeds onto the branches of other shrubs and trees – or depositing them in their droppings – they unwittingly procure new hosts for the desert mistletoe.¹

Saguaro Cactus

The saguaro cactus is native to Arizona, Mexico, and parts of California. Biologists believe that some may live for over 200 years, but the savage conditions in which it survives means it grows incredible slowly – an eight-year-old plant may only be 3-5cm (1-1.5 inches) tall. Eventually, it can reach around 15 metres (50 feet) in height and weigh over six tons.² These cacti, like many others – expand as they take in water, when it is available, then gradually contract as the water is consumed during times of drought.³ Over the years, local people have put the saguaro to good use, in a number of surprising ways. Its fruits and seeds have been harvested for food, whilst the “ribs” of the cactus have been fashioned into walking sticks, splints for the injured, and also used in the construction of cradles for babies.⁴

Teddy Bear Cholla and the Packrat

From a distance, Cylindropuntia bigelovii look soft and fluffy, hence the common name of “Teddy Bear Cholla”. However, these cacti are anything-but cuddly. Found in the deserts of Colorado, California, and Mexico, they’re covered in silvery, sharp needles up to 2.5cm (1 inch) long and detach in segments – or balls – as part of the reproduction process. These spiky balls stick to the fur of passing animals and can be carried a long way before being shaken free, where they will eventually take root. Cannier animals have identified the protective potential they offer: packrats collect these balls of sharp needles to use as a form of barricade, to defend their burrows from predators.⁵

Creosote bush

Most commonly found in North American deserts, the creosote bush (Larrea tridentata) is a medium-sized evergreen shrub and can reach up to 10 foot in height. It’s a sturdy plant, built to withstand the temperature variations of its location, where day and night can differ by 21°C (70°F). Even in times of drought, it is able to photosynthesize.

Its rich-green leaves have adapted to their environment by developing a waxy coating. This serves a dual purpose: it helps it cope with the desert heat and reduces the amount of water lost through evaporation. In the spring and summer months, it produces yellow velvety flowers that grow up to 2.5cm in length.

This bush carries its name from the pungent odour it produces when wet – creosote being a type of oily liquid that is often used as a wood preservative.3 The Creosote bush also takes on other plants in the battle for scarce water supplies in order to survive.⁶

The Tumbleweed, Selaginella

Some desert plants use the ‘tumbleweed’ method of propagation. In late autumn, they shrivel up and then become detached from their roots or stems by gusts of wind. The tumbling causes seeds or spores to disperse en route, which germinate when the rains come.⁷

One such tumbleweed is Selaginella lepidophylla, which can be found in the Chihuahuan Desert of the United States and Mexico. It’s also known as the ‘Resurrection Plant’ or the ‘Resurrection Fern’ because when the weather turns dry, it appears to die, curling up into a brown, dry ball, but later unfurls its leaves in the presence of moisture.⁸ This is an adaptation to survive long dry periods in the desert and it can remain in its dormant state for years. Amazingly, it can also lose up to 95% of its moisture without resulting in any tissue damage. In its “dead”, tumbleweed state, its often carried by the wind and will revive within just a few hours of reaching water. When it does so, it displays vibrant, green fronds, rather like a fern.⁹

The Cardon Cactus

Plants don’t only form symbiotic relationships with animals and plants to survive in seemingly inhospitable desert conditions. In the volcanic region of the Baja California Sur mountain range, the Cardon cactus (Pachycereus pringlei) thrives on little more than bare rock, all thanks to rock-dissolving bacteria.

These microorganisms live in the roots of the cactus, breaking down rock to allow those roots to grow – but that’s only part of this incredible relationship. The endophytic bacteria also dissolves the rock, breaking it down into the minerals and nitrogen that helps the plant to survive, while in return, the cactus provides the bacteria with carbon. This remarkable discovery was made by Dr Yoav Bashan,¹⁰ a biologist at the Northwestern Center for Biological Research in La Paz, Mexico. His research showed that not only are the bacteria in the cells of the root, but they’re also in the seeds of the Cardon cactus, allowing the bacteria to be passed on to future generations.¹¹

Baobab Tree

The baobab tree appears as if upside down, branches in the ground and roots in the air – and it is as remarkable as it is strange-looking. The definition of slow and steady, Baobabs can live for 2000 years and don’t fruit until they are 200 years old. They are known for being practically indestructible, capable of surviving brutal temperatures, fire and drought – and if the bark is stripped off, it grows back. The baobab tree's spongey wood permits it to hold tens of thousands of gallons of water for consumption during the desert's dry season. It’s for this reason that it's known as ‘the tree of life’, with animals and humans also taking advantage of its stored supply.¹²

Despite the astonishing adaptations these plants have evolved to cling to survival in the most hostile of environments, they are still under threat – from climate change. Our ability to control global warming is pivotal to their survival. 

Discover more astonishing plant-animal relationships with new Sir David Attenborough series The Green Planet, which explores the wondrous interconnected world of plants. Find out where to watch in your region here. 🌱

Featured image © BBC Studios NHU

References: 

1. Desert Mistletoe, 2. Saguaro Statistics, 3. Thirsty Cacti, 4. Saguaro put to Good Use, 5. Teddy Bear Cholla and the Packrat, 6. Creosote Bush, 7. Why Tumbleweeds Tumble, 8. Resurrection Fern, 9. Asleep for Years, 10. Dr Yoav Bashan's Research, 11. Crafty Cactus, 12. The Baobab Tree