Wolffia arrhiza

Description

Wolffia arrhiza is an aquatic plant which grows in quiet water bodies such as ponds. The plant's green part, known as the frond, is a spherical structure about 1 mm wide. It has a flat top that allows it to float on the water's surface. It has a few parallel rows of stomata. It often multiplies by vegetative reproduction, with the rounded part budding off into a new individual. In cooler conditions, the plant becomes dormant and sinks to the bottom of the water body to overwinter as a turion. As a mixotroph, it can produce its own energy by photosynthesis or absorb it from the environment in the form of dissolved carbon.

Taxonomy

Wolffia arrhiza was first described in 1771 by Linnaeus as Lemna arrhiza in the genus Lemna, known for several duckweed species. It was transferred to the current genus Wolffia in the 19th century based on works of Johann Horkel and the third edition of the Flora von Schlesien preußischen und österreichischen Antheils by Christian Friedrich Heinrich Wimmer in 1857.

Human uses

This tiny plant is a nutritious food. Its green part is about 40% protein by dry weight and its turion is about 40% starch. It contains many amino acids important to the human diet, relatively large amounts of dietary minerals and trace elements such as calcium, magnesium, and zinc, and vitamin B. The plant is prolific in its reproduction, growing in floating mats that can be harvested every 3 to 4 days; it has been shown to double its population in less than four days in vitro.

It is also useful as a form of agricultural and municipal water treatment. It is placed in effluent from black tiger shrimp farms to absorb and metabolize pollutants. The plants grow quickly and take up large amounts of nitrogen and phosphorus from the water. Nile tilapia, and chickens.

References

References

1. Lansdown, R.V.. (2019). "''Wolffia arrhiza''".
2. "Rootless Duckweed ''Wolffia arrhiza'' (L.) Horkel ex Wimm.".
3. Pietryczuk, A., et al. (2009). [http://www.pjoes.com/index.php?s=abs_id&id=2009180515 The effect of sodium amidotrizoate on the growth and metabolism of ''Wolffia arrhiza'' (L.) Wimm.] ''Polish Journal of Environmental Studies'' 18:5 885-91.
4. Pan, S. and S. S. C. Chen. (1979). [http://ejournal.sinica.edu.tw/bbas/content/1979/2/bot202-01.PDF The morphology of ''Wolffia arrhiza'': A scanning electron microscopic study.] ''Bot Bull Academia Sinica'' 20 89-95.
5. Czerpak, R., et al. (2004). [http://www.botany.pl/pubs-pdf/Acta%20Societatis%20Botanicorum/2004/4_269275.pdf Biochemical activity of auxins in dependence of their structures in ''Wolffia arrhiza'' (L.) Wimm.] {{Webarchive. link. (2011-09-11 ''Acta Societatis Botanicorum Poloniae'' 73:4 269-75.)
6. {{GRIN
7. "Wolffia arrhiza in Flora of North America @ efloras.org". efloras.org.
8. Heywood, Prof. V.H.. (1978). "Flowering plants of the World". Mayflower Books.
9. Al Khateeb, N. {{usurped
10. Fujita, M., et al. (1999). Nutrient removal and starch production through cultivation of ''Wolffia arrhiza''. ''Journal of Bioscience and Bioengineering'' 87:2 194-8.
11. Czerpak, R.. (2003). "The Effect of β-estradiol and Corticosteroids on Chlorophylls and Carotenoids Content in ''Wolffia arrhiza'' (L.) Wimm. (Lemnaceae) Growing in Municipal Bialystok Tap Water". Polish Journal of Environmental Studies.
12. It has long been used as a cheap food source in [[Myanmar]], [[Laos]], and [[Thailand]], where it is known as ''khai-nam'' ("eggs of the water").Bhanthumnavin, K. and M. G. McGarry. (1971). [http://www.nature.com/nature/journal/v232/n5311/abs/232495a0.html ''Wolffia arrhiza'' as a possible source of inexpensive protein.] ''Nature'' (letter) 232:495.
13. National Academy of Sciences. [https://books.google.com/books?id=n2krAAAAYAAJ&dq=wolffia+arrhiza+protein&pg=PA149 Making aquatic weeds useful: Some perspectives for developing countries.] 1976. Page 149.
14. Körner, S., et al. (2003). [https://www.soils.org/publications/jeq/articles/32/5/1583 The capacity of duckweed to treat wastewater.] ''Journal of Environmental Quality'' 32:5 1583-90.
15. Suppadit, T., et al. (2008). [http://www.scienceasia.org/2008.34.n2/scias34_163.pdf Treatment of effluent from shrimp farms using watermeal (''Wolffia arrhiza'').] {{Webarchive. link. (2020-12-14 ''ScienceAsia'' 134 163-8.)
16. The plants that grow in the wastewater can then be used as [[Compound feed
17. Chareontesprasit, N. and W. Jiwayam. (2001). ##[http://docsdrive.com/pdfs/ansinet/pjbs/2001/618-620.pdf An evaluation of ''Wolffia'' meal (''Wolffia arrhiza'') in replacing soybean meal in some formulated rations of Nile tilapia.] ''Pakistan Journal of Biological Sciences'' 4:5 618-20.