Here's cat hair, dog hair, and horse hair. There's my hair and your hair. But did you ever hear of geranium hair?
Long hairs and short hairs. Wet hairs and dry. The plant world has lots of hair.
Plants use hair for some of the same reasons animals do: to keep them warm, cool, or protected. Plants also use hair to collect food or distribute seeds. Insect-eating pitcher plants even have down-turned hairs to keep insects from escaping.
The thick, wooly white hair of the lamb's-ears plant keeps it cool and makes it hard for aphids (small, plant-juice sucking insects) to attack the plant. White-colored hairs or spines on cactuses reflect sunlight and help keep the plant cool. The tip of the hair of the sundew plant has sticky-liquid-producing glands, which help to catch the plant's insect lunch.
There are other, modified hairs that don't look like hair at all. Open an orange or grapefruit by peeling it. 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.
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 position to lay their eggs.
Stiff hairs (spines) are hard and sharp and defend the plant against animal grazers. 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 look very hairlike indeed. They may be soft, flexible, and often white to reflect the sun.
Finally, there are plants living near or in salt water. Some live near the sea; some live in tidal waters. Sea spray 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.
Plant hair for human use
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 pillow cases 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.
Hair is found on stems, leaves, flowers, fruit, and roots. Take a good look around you and see how many kinds of hair you can find on plants or their fruit. Some of them will be easy to spot. To see others you will need a magnifying glass. Some have to be seen under a microscope.
THE HUNT FOR PLANT HAIR STARTS HERE
*You may need a magnifying glass to find some of these items*
Leaves of magnolia or sycamore trees. (Check the undersides of the leaves.)
Leaves and stems of tomato, potato, petunia, or lamb's- ears plants.
Sundew plants or pitcher plants.
The inside of a citrus fruit. (See above photo, right.)
The stem of a raspberry cane, hollyhock, sunflower, or the outside skin of a kiwi fruit. (See photo, left.)
Hairs on seeds of dandelion, coltsfoot, and thistle look like parachutes. What do they do?
Pods of the wisteria are like velvet. What purpose might this thick hair serve?
If you have a cactus, does it have large spines or short hair-like spines in bunches? Is there a whorl of hairs protecting the tender top? What color are they?
Open a well-developed (but still green) milkweed pod. Notice how the seeds are positioned. The silky hairs are lined up, ready to expand and carry the seeds away.
A HAIRY LIST
* Here are some words used to describe plant parts that look hairlike.
Awn (rhymes with yawn) -- noun; slender bristlelike fiber or fibers, as on the head of barley, oats, or wheat; also known as a grain's "beard."
Bristle -- noun; a stiff, prickly hair. Example: the hairs on the stalks of raspberry or blackberry canes.
Cilium (SIL-ee-um) -- noun; very fine hair-like filaments that extend from certain plant cells, as on the edges of some leaves.
Felt -- noun; a very thick covering of hairs or fibers.
Fiber -- noun; a threadlike structure. Example: the white fibers attached to cotton seeds that are spun into cotton thread.
Glochidia (glo-KID-ee-uh) -- noun; barbed hairs or bristles, as on certain cactuses.
Pectinate (PECK-tuh-nayt) -- adj.; having toothlike projections like those on a comb.
Radiating -- adj.; spread outward. Some cactuses have radiating glochidia (spines).
Recurved -- adj.; curved back upon itself. Example: the thorn of a rose.
Spine -- noun; in cactuses, larger than a bristle; thought to be a modified leaf. May be erect, stiff, and woody, or flexible and hairlike.
Trichome (TRY-cohm) -- noun; a hairlike structure growing on the epidermis (skin) of a plant. Examples: peach fuzz, the skin of a kiwi fruit.