Plants use hair to keep them warm, cool, or protected. Plants use hair to collect food, distribute seeds, insect-eating pitcher plants even have down-turned hairs to keep insects from escaping.
The hair is a survival strategy employed by many plants.
Old man, lady, and other cacti have the development of a hairy layer called a “tomentum.”
The tomentum helps the plant stay cool in the hot desert sun when the traditional route of cooling used by plants, transpiration, is unavailable.
In dry environments, however, sweating to cool down is a waste of precious water, and so desert plants keep their stomata closed during the day, preventing water loss.
At night, these plants open their stomata, in order to take in carbon dioxide for photosynthesis.
In environments where low humidity is a challenge, a tomentum can provide extra protection against drying out by trapping a layer of moist air close to the surface of the leaf or stalk.
The drawback to this method is that now this layer of air is very humid, and so it can’t take any more water from transpiration. So the plant has to turn to another strategy. The solution to cooling down is to grow more hair.
All those hairs are white to reflect light before it has a chance to get absorbed and turned into heat. Just as wearing a white can help keep you cool in the sun. Growing more white hair means the cactus can reflect more light.
Hairy Situations
Why did these plants evolve hair?
Aphids are just one type of insect that likes to eat plants. Some plant hairs have tiny hooks that catch the invaders.
Sometimes the hair makes it hard for the insects to feed on the leaves. In other cases, dense hair makes it hard for the insects to move around on the plant or get into a position to lay their eggs.
Stiff hairs (spines) are hard and sharp and defend the plant against animal grazers such as tortoises and goats. Most animals prefer their meals without stickers.
Spines also help screen the plant against too much sun. This helps keep the plant from drying out or being burned by the sun.
The spines on a cactus are modified leaves, while the pads are modified stems. Some of those modified leaves are soft, flexible, and often white to reflect the sun.
Seaspray and tidal water carry a lot of salt. The plants living in these conditions need a way to intercept and eliminate salt. Plant hair protects some plants against toxic amounts of salt.
There are modified hairs on an orange or grapefruit. Remove one of the sections of the fruit and gently take away the membrane.
Look carefully at each cell of juice. You are looking at a modified hair. It is made to hold the liquid we like to drink. If that fruit had fallen to the ground and begun to decompose, the juice would have helped the seed to germinate and grow.
Plant Hair For Humans?
One of the most important plant hairs for human use is that of the cotton plant. Long white fibers grow on the seeds. When spun into threads and then into cloth, they form many of the clothes we wear, sheets and pillowcases we sleep on, and towels we take to the bath and beach.
Another hair that grows on seeds is that of the silk-cotton tree, also known as the Kapok tree.
The hair of the Kapok tree is used for mattresses, flotation devices, and as insulation.
Woolly hairs on the plants in this article have been used for pillow filling in Mexico, Peru, and other places where these cacti grow.
How Many Species Of Hairy Cactus Are There?
Meet The Ol’ Man…
Espostoa
Espostoa
The plant blooms at night from a lateral
It grows columns up to 23 feet tall in the wild, but only 10 feet tall when cultivated. There are 18 to 25 ribs.
The ribs and the sharp are mainly hidden by tissue woolly. It branches only after several years.
Cephalocereus
The widespread propagation and popularity in cultivation have reduced the demand for wild populations.
The hairs are only the radial spines of the cactus because they conceal formidable sharp yellow central spines that belie the inoffensive appearance of the hairy covering.
Cephalocereus
The coat is a particularly striking silvery white on the young cactus; as the plant ages, the stem begins to lose its covering. The flowers are red, yellow, or white, though the plant may not flower until 10–20 years old.
Cephalocereus
In 1996, scientists working for the University of Texas found that the Cephalocereus
Oreocereus
Slow growing, O. trollii produces red flowers, typically after reaching several feet in height. Though listed as Least Concern by the IUCN, the plant is collected extensively and in some areas is threatened
Propagation is through woody stem cuttings. Allow cut surface to callous over before planting.
Or allow the unblemished fruit to ripen and seed. Clean and dry
Oreocereus
It is named for its fluffy white hair, which may protect it from intense sunlight and extreme temperatures.
Growing to around 10 ft tall, O.
Blooms in spring with long, tubular red flowers, this cactus is pollinated by hummingbirds in spring.
Espostoa
Growing to 7 feet tall in the wild, however, raised in a pot it will only reach up to 10 inches in 10 years. The long woolly spines that cover and hide the body of the plant including sharp white, yellow or red spines up to 1.5 inches long.
Spines easily detach from the plant. As the cactus matures all the spines become darker. The stems are erect and columnar and branch at the base to form clumps. Flowers are rare but white blooms up to 2 inches wide appear at night. Berry-like fruits are produced with edible dull black seeds inside.
Opuntia
It belongs to the genus Opuntia prickly pear cacti. It is also widespread in Nuevo Leon, Tamaulipas (northern Mexico).
Meet The Ol’ Lady…
Mammillaria
Reddish purple flowers are borne in spring and summer, sometimes forming a complete ring around the apex of the plant.
The solitary spherical stems grow to 5 inches in diameter, are covered in white down and white spines.
Mammillaria candida is a ball-shaped plant with white felt or fuzz on the skin of the plant. It has up to 120 radial spines, cylindrical tubercles, 4-7 axillary hairs and rose pink flowers.
Mammilloydia candida is a slow-growing, clustering species that reproduces easily by cutting.
Parodia scopa ball or cylinder shaped cactus native to upland southern Brazil and Uruguay. It is a ball- or cylinder-shaped cactus growing to 2–20 inches tall, with a spiny, woolly crown and pale yellow flowers in summer.
Mammillaria
Mammillaria
The cacti are surprisingly easy to grow and this book offers everything you need to know at a glance in one handy and superbly illustrated practical guide.
As well as a directory of 50 recommended varieties there is expert advice on planting, cultivation, and care.
Some cacti live up to 200 years in the wild.
They do not bloom for 10 to 20 years!
Cactus that have evolved to have hair demand better drainage than most cactus species. Add a measure of perlite to the standard cactus mix of three parts potting soil and one part sharp sand. An alternative cactus mix includes one part peat moss, one part sand, and one part perlite.
These guys live in the harshest conditions known to plants. If you are looking to maximize beard growth, situate the old man in a bright, if not exceptionally hot, location.
You can even clean its hair, should it darken, with a very dilute shampoo solution. Brushing is optional.
If you purchase your cactus in the winter, just set it on your patio until spring. Cactus prefer to be planted in the ground when the weather warms. In cold soil, cactus becomes dormant and any excess water can kill it.
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What is the difference between the old man cactus an the old lady cactus
While I am not sure of the exact answer, I think old men cactus look like hairy people with white hair and beards while old lady cactus look like pincushions and pillows.
With the day of age we are in where you are not allowed to call Mr. Potatoe head a Mr… maybe they will not allow the cacti to be sexually described?
haha I am just kidding!
Thanks for the awesome question! Have the best night!