The Hidden Beauty of Xerophytes
A xerophyte (Greek: xeros = dry, phuton = plant) is a type of plant that has adaptations that enable it to survive in environments that have minimal sources of liquid water. These environments may include both hot and cold desert regions like the Sahara and the Arctic. In addition to surviving arid environments, the adaptive nature of xerophytes has also enabled them to be found in almost all types of terrains, climates, and weather patterns. They are found in salt marshes, saline, and acidic soils. Other xerophytes can be found on dry river banks, beaches, in sand dunes, and even on bare rock surfaces.
Despite the resilience and adaptive nature of xerophytes, they are, however, not confined to arid environments, but can also be found in backyard flower gardens, container gardens, herb gardens, desert gardens, rock gardens, and even inside the house.
Different xerophytes inhabit different parts of the world, but they all share a similar structural morphology and have a similar basic fundamental physiology.
What has enabled xerophytes to survive in a wide range of environments?
Characteristics of Xerophytes
The survival adaptations and characteristics of xerophytes are divided into two groups based on their morphology and physiology.
Xerophytic plants usually have similar shapes, sizes, and forms, even if the plants are not geographically located in the same area or are related. This is because the morphology or structures of xerophytic plants are all designed to adapt to environments with less liquid water. Some common adaptations include:
- Reflective features, usually in the form of waxes or hairs on its surface, help reflect sunlight and reduce the loss of water through transpiration.
- Thick cuticles containing wax are designed to prevent loss of water.
- Reduction of surface area by developing smaller leaves and fewer branches, thereby reducing the surface that is exposed to water loss by transpiration and evaporation.
- Forming a water vapor-rich environment by developing tiny hairs that shelter the stomata and enable them to maintain a humid environment around them.
Lack of readily available water causes a plant to experience stress, this causes the physiological processes within the plant to become unstable and less efficient in the production activities. Xerophytes, however, are able to operate with minimal water intake due to their well-adapted physiological and biochemical capabilities. These adaptations include:
- Hormonal signaling to close the stomata during the day to prevent water loss by evaporation, and opening the stomata at night in the presence of mist or dew.
- Water storage in their root, trunk, stem, and leaf structures.
- Reducing the rate of germination and growth. The low speed of germination and growth uses less water.
- Stopping its growth processes and becoming dormant in seasons of less water. They may appear dead but will resurrect when water is readily available again.
Common Xerophytic Plants
Despite having similar morphology and physiology, the physical appearances of xerophytes differ from region to region; xerophytes from the same region and family may also appear very different. This is a consequence of different adaptation mechanisms employed by different xerophytic plants. Some xerophytic plants are ephemeral annuals or drought evaders, some are succulents, and others are non-succulents.
Some common xerophytes include:
Scientifically known as Ananas comosus, the pineapple is perhaps the most popular xerophyte. Originally cultivated in South America in the 17th century, the pineapple is now the third most important tropical fruit in world production. In addition to being incredibly delicious, pineapples are rich in vitamins, enzymes, and antioxidants.
Aloe vera, sometimes referred to as a 'miracle plant' due to its many health benefits, is another popular member of the xerophyte family. Aloe is a genus name used to refer to a group of more than 500 species of succulent plants. These plants occur naturally in tropical, semi-tropical, and arid areas of the world.
Pines are woody plants and prominent members of the xerophyte family. The smallest pines at maturity are basically shrubs. The largest pines are native to North America and can exceed 250 feet or more in height. Popularly used as Christmas trees, pine trees come in all shapes and sizes.
Cactus is another member of the xerophyte family, with over 1000 known species. They are succulent perennial plants native to North and South America, and some cacti are native to East Africa and Asia. Cacti vary in size and general appearance, some are able to produce edible fruits that can be cultivated.
Agaves are xerophytes common in hot and arid regions of the world, known for their strong and large fleshly leaves. They are commonly kept as ornamental plants. Blue agaves today are popularly used in the production of tequila, while some other agaves are used in soap production.
Esparto, also known as esparto grass, is a perennial fiber xerophytic grass. Indigenous to North Africa and Southern Europe, esparto grass can be found in other dry and arid regions of the world. Primarily used to craft ropes and baskets, it is sometimes used in the production of clothes and paper.
Nerium Oleander is a highly toxic and poisonous member of the xerophyte family. All parts of the plant are considered poisonous. In fact, it is one of the most poisonous known plants that are usually grown in flower gardens. The plant is tolerant of prolonged dry periods and poor soil, and this has enabled the plant to survive in different regions of the world. In ancient times, the plant was predominantly used as a poison in warfare.
Why You Should Grow More Xerophytes
Xerophytes may not be roses in every garden, but their diverse uses and applications make them essential members of the plant community. In the garden, xerophytes require less maintenance, are able to survive with less available water, can grow in both high and low temperatures, and are not prone to diseases. Anyone starting a garden should consider adding xerophytes first.
- Michael Hickey, Clive King, The Cambridge Illustrated Glossary of Botanical Terms, Cambridge University Press, 2001.
- Hewitt, Terry, The Complete Book of Cacti & Succulents, London: Covent Garden Books, 1993.
- Taylor D.J, Green & G.W. Stout, Biological Science 3rd edition. Cambridge University Press, 2001.
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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