One of the important functions of seeds and fruits is dispersal; a mechanism to establish the embryo-bearing seeds in a suitable place away from their parental plants. There are several mechanisms for seed and fruit dispersal but one of the most prevalent is wind.
There are 5 main types of wind dispersal including Gliders, Parachutes, Helicopters (Whirlybirds), Flutterer/Spinners, and Cottony Seeds & Fruits
Gliders include seeds with 2 lateral wings that resemble the wings of an airplane. They become airborne when released from their fruit and sail through the air like a true glider. One of the best examples of this method is Alsomitra macrocarpa, a tropical vine in the Gourd Family. Football-sized gourds hang from the vine high in the forest canopy, each packed with hundreds of winged seeds. The seeds have two papery, membranous wings, with combined wingspans of up to 5 inches (13 cm). They reportedly inspired the wing design of some early aircraft, gliders and kites. Although the seeds vary in shape, some of the most symmetrical ones superficially resemble the shape of the modern Stealth Bomber.
Parachutes include seeds or achenes (one-seeded fruits) with an elevated, umbrella-like crown of intricately-branched hairs at the top, often produced in puff-like clusters. The slightest gust of wind catches the elaborate crown of hairs, raising and propelling the seed into the air like a parachute. This is the classic mechanism of dispersal for the dandelion (Taraxacum species). Its seeds have literally blown across mountain ranges, colonizing fields and open land throughout the United States.
Helicopters (also called Whirlybirds) include seeds or one-seeded fruits (samaras) with a rigid or membranous wing at one end. The wing typically has a slight pitch (like a propeller or fan blade), causing the seed to spin as it falls. Depending on the wind velocity and distance above the ground, helicopter seeds can be carried considerable distances away from the parent plant. The spinning action is similar to auto-rotation in helicopters, when a helicopter "slowly" descends after a power loss. Numerous species of trees and shrubs in many diverse and unrelated plant families have evolved this ingenious method of seed dispersal, good examples of convergent evolution. Representative examples of helicopter seeds and one-seeded fruits (called samaras) include the Maple Family (Aceraceae), the Olive Family (Oleaceaea), and the Pine Family (Pinaceae).
Although their mode of dispersal is similar to single-winged helicopter seeds, the flutterer/spinners include seeds with a papery wing around the entire seed or at each end. When released from their seed capsules they flutter or spin through the air. Whether they spin or merely flutter depends on the size, shape and pitch of the wings, and the wind velocity. This method of wind dispersal is found in numerous species of flowering plants such as the Jacaranda (Jacaranda mimosifolia), the American elm (Ulmus americana), and the Tabebuia.
Cottony seeds and fruits include seeds and minute seed capsules with a tuft (coma) of cottony hairs at one end, or seeds embedded in a cottony mass. Some of the examples in this group are very similar in function to parachute seeds, but probably are not carried as far by the wind. Many plant families have this type of wind dispersal, including the Willow Family (Salicaceae), the Cattail Family (Typhaceae), and the Sycamore Family (Platanacea)..
One fuzzy brown cattail spike may contain a million tiny seeds. Each seed has a tuft of silky white hairs and is small enough to pass through the "eye" of an ordinary sewing needle. They are shed in clouds of white fluff and float through the air like miniature parachutes. A cattail marsh covering one acre may produce a trillion seeds, more than 200 times the number of people in the world. The fluffy seeds have been used for waterproof insulation and the buoyant filling of life jackets. In addition, each plant produces billions of wind-borne pollen grains; in fact, so much pollen that it was used as flour by North American Indians and made into bread.