Saturday, February 9, 2008

Flying Seeds: Reproduction by Wind Dispersal and Igo Etrich

Chris' Comment in class about helicopter seeds got me thinking about all the different forms of plants that disperse seeds with flying/wind abilities.
Here's a fab article I found on the topic...

Igo Etrich (1879 - 1967)

The 'seed of an idea'

The Witness of Nature

Plants have also mastered the art and science of aviation. And they did it long before Orville and Wilbur Wright propelled their frail craft into the air. We see this most often in the way seeds navigate to suitable soil. If a tree dropped its seeds straight down, the seedlings would have to try to grow in the shade of the parent tree and would soon choke each other out.

Seeds need to be transported away from the parent tree or plant, and this is accomplished in a variety of ways. The most interesting example is probably the winged seed of the tropical liana. It grows high up in the branches of its parent tree amid beautiful, shining green leaves. The liana seed develops two curved wings, transparent, gleaming, and very elastic. When the seed releases from the tree, it glides away in the breeze.

Coldly objective scientists grow eloquent when observing this bit of plant aeronautics. One professor described the liana glider in this way:

'Circling widely, and gracefully rocking to and fro, the seed sinks slowly, almost unwillingly, to the earth. It needs only a breath of wind to make it rival the butterflies in flight.'

Early aviation pioneers were also impressed with the perfect flight of the liana seed. In building craft light enough to soar in the wind, stability was the key. Early flying machines kept falling apart. But the liana glider's gossamer winds were remarkably stable. And so two flying pioneers, Etrich and Wels, made use of the liana seed in designing a tailless glider.

The craft that resulted in 1904 proved to be a milestone in aviation history, gliding for about 900 meters. Another technological marvel pointing to nature as the mother of invention.

Blowing In The Wind - Seeds & Fruits Dispersed By Wind

which says in part (and paraphrased here) ...

Like an endless army of parachutists released from an airplane, seeds and fruits travel the wind currents and gentle breezes of the earth. Literally hundreds of species have adopted this remarkable method of dispersal including seeds that with 2 lateral wings and when released from their fruit sail through the air like a glider.

Makrozanonia Metacarpata/Alsomitra macrocarpa

One of the best examples of this method of dispersion is the winged seed of the tropical Asian climbing gourd Alsomitra macrocarpa a tropical vine in the Gourd Family (Cucurbitaceae) native to the Sunda Islands of the Malay Archipelago. 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 a combined wingspan of 5 inches (13 cm) and capable of gliding through the air of the rain forest in wide circles. Although the seeds vary in shape, some of the most symmetrical ones superficially resemble the shape of the "flying wing" aircraft or a modern Stealth Bomber.

According to Peter Loewer, Seeds: The Definitive Guide to Growing, History, and Lore, 1995, the aerodynamic seeds spiral downward in 20 foot (6 meter) circles, although a gust of wind would probably carry them much farther away.

Igo Etrich : The Gliders


Etrich's Zanonia Glider flown as a Kite, 1904


The Etrich-Wels Glider, 'Etrich's Leaf', 1906


Igo Etrich in his glider of 1907

Igo Etrich : The Powered Aircraft


Etrich-Wels Tailless parasol, 1908


Etrich-Wels, Tailless parasol, 1908, 3view

The Igo Etrich Taube

The Taube's wing design is based on the zanonia tree seed pod, which drifts through the air for great distances. First produced for sporting purposes, Taubes were later used for observation and training by Germany and Austro-Hungary during World War I. Ironically, the Taube (meaning Dove, the peace symbol) was first to drop bombs in war; the Balkans in 1911 and Paris in 1914.

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