permaculture

["Lawrence F. London, Jr." <lflj@bellsouth.net>]

Anyone here interested in duckweed and its many uses?

Here's some basic information on it:

http://www.mobot.org/jwcross/duckweed/duckweed.htm
The family of duckweeds (botanically, the Lemnaceae) are the smallest flowering plants.  These plants grow floating in 
still or slow-moving fresh water around the globe, except in the coldest regions.  The growth of these high-protein 
plants can be extremely rapid.  Lemna is one of the best known of this group and has been the subject of much research.

Researchers are using these plants to study basic plant development, plant biochemistry, photosynthesis, the toxicity of 
hazardous substances, and much more.  Genetic engineers are cloning duckweed genes and modifying duckweeds to 
inexpensively produce pharmaceuticals.  Environmental scientists are using duckweeds to remove unwanted substances from 
water.  Aquaculturalists find them an inexpensive feed source for fish farming.

Botanical Facts
http://www.mobot.org/jwcross/duckweed/duckweed.htm

Wikipedia
http://en.wikipedia.org/wiki/Lemnaoideae
Lemnaoideae
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Lemnaoideae
Close up of two different duckweeds:
Spirodela polyrrhiza and Wolffia globosa.
The very tiny Wolffia plants are under 2 mm long
Scientific classification
Kingdom:     Plantae
(unranked):     Angiosperms
(unranked):     Monocots
Order:     Alismatales
Family:     Araceae
Subfamily:     Lemnoideae
Genus

    * Spirodela
    * Landoltia
    * Lemna
    * Wolffiella
    * Wolffia

Lemnaceae is a family of flowering plants, also known as the duckweed family, as it contains the duckweeds or water 
lentils. Since duckweeds are now considered to be a branch of the arum or aroid family (Araceae)[citation needed], the 
name 'Lemnaceae' is rapidly falling out of use among taxonomists[citation needed], who treat it as a subfamily called 
Lemnoideae[citation needed].

These plants are very simple, lacking an obvious stem or leaves. They consist of a small 'thalloid' or plate-like 
structure that floats on or just under the water surface, with or without simple rootlets. The plants have become highly 
reduced from their relatives in Araceae. Reproduction is mostly by budding, but occasionally a flower consisting of two 
stamens and a pistil is produced (some view the 'flower' as a pseudanthium, or reduced inflorescence, with three 
unisexual flowers, derived from the spadix in Araceae). The fruit is a utricle, a sac containing air and a seed designed 
to float. The flower of the Wolffia is the smallest flower in the world; measuring in at a size of 0.3 mm long.[1]

Duckweed is an important food source for waterfowl and are eaten by humans in some parts of Southeast Asia (as 
khai-nam). Some duckweeds are used in freshwater aquariums and ponds where they may spread rapidly and, in a large pond, 
may be difficult to eradicate once established. The plants can provide nitrate removal (if cropped) and cover for fry. 
The plants are used as shelter by pond water species, such as bullfrogs and bluegills. The duckweeds are important in 
the process of bioremediation because they grow rapidly, absorbing excess mineral nutrients, particularly nitrogen and 
phosphates. A cover of duckweeds will reduce evaporation of water compared to a clear surface.

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In the context of food cropping in Vanatu I submitted this idea to a friend 
in Sanet:

I would suggest biointensive, no-till, permanent, mulched (compost and 
cover/companion crops)
raised beds with drainage ditches cycling nutrient rich water from gardens to catchment posds growing duckweed. The 
duckweed will extract 85% of all nutrients in the water, are high protein (as high as soy), low fiber and can be used as 
human and livestock food or as a nitrogen-rich soil amendment (read: fertilzer) to put back onto the crop beds. Duckweed 
can be used to purify sewage and manure lagoons, producing regularly harvestable duckweed as a farm input. When duckweed 
is dried its natural state is granular, perfect for storage and application on gardens.


A more robust livestock component of their subsistence farming system would be a good thing. Then you have the nutrients 
and microbes to make enhanced compost to greatly enhance their growing beds. Cover crops could be really beneficial. 
Permanent notil biointensive raised beds are almost self-maintaining microbe-wise and almost nutrient-wise too. Their 
food crop production could be usignificantly upgraded through the addition of manure to their compost. Keep the gardens 
in one location permanently; keep livestock nearby, make thee compost there also. Save labor for manicuring and 
maintaining fertility in the beds. Just a thought. Grow crops on slop[es that are suited to that terrain and others on 
more level ground; cycle water borne nutrients from one garden to another with ditches. Overflow can go to duckweed lagoons.