Tag Archives: weird plants

Friday Fellow: Tree Tumbo

by Piter Kehoma Boll

Today I’m introducing one of the most bizarre plant species in the world. Found in the Namib desert, in Namibia and Angola, the Welwitschia mirabilis, usually simply called welwitschia or tree tumbo in English, is the solely member of the order Welwitschiales, a group of gymnosperms in the division Gnetophyta.


A specimen of Welwitschia mirabilis in Naukluft, Namibia. Photo by Sara&Joachim*

The tree tumbo has a unique appearance. The seedlings have two cotyledons (the original leaves produced by the seed) and later develop two permanent leaves that grow opposite (at right angles) to the cotyledons. These permanent leaves grow continuosly, reaching up to 4 m in length. While growing, the leaves split and fray into several straps and occupy an area of about 8 m in circunference around the plant. The stem is woody and the flowers appear on a central part called crown. The species is dioecious, meaning that male and female flowers appear in different plants. Pollination is usually carried out by insects.

Living up to 2 thousand years, the tree tumbo is a very peculiar desert plant. Its leaves are broad and very large, different from what is the rule in the desert. Its root system is also very shallow, not penetrating deep in the ground. It seems that most of the water used by the plant is captured by the leaves from the morning fog.

Although having a very restrict range, the tree tumbo is not (yet) and endangered plant, as its population is considerably large. However, due to its popularity, some areas attract collectors, and since its growth is so slow, it may eventually become a vulnerable plant.

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Bornmann, C. H. 1972. Welwitschia mirabilis: paradox of the Namib Desert. Edeavour, 31(113):95–99.

Wikipedia. Welwitschia mirabilis. Available at <https://en.wikipedia.org/wiki/Welwitschia&gt;. Access on March 1, 2017.

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Friday Fellow: Sailor’s Eyeball

by Piter Kehoma Boll

Once more our Friday Fellow is hidden among the coral reefs. Its name: Valonia ventricosa, commonly known as sailor’s eyeball.

This green shiny alga is one of the largest single-celled organisms, reaching more than 5 cm in diameter. It is found in tropical seas all around the world, usually associated to coral reefs. It has a spheric to oval shape and a shiny dark to light green surface, making it look like a cut gemstone.

A living jewel of the sea,

A living jewel of the sea. Credits to Philippe Bourjon.

Due to its unusually large size for a unicellular organism, the sailor’s eyeball has been extensively studied regarding its cell wall structure, and it seems to be quite peculiar. The cellulose fibers in its cell wall, which is almost as thick as the cytoplasm, are arranged in a complex structure, including parallel and crossing fibers, as well as some strange fiber swirls with no known function. Its membranes do not seem to have any aquaporines, i.e., pores for letting water go through.

On your next visit to a coral reef, try to find some!

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Eslick, E. M.; Beilby, M.J.; Moon, A. R. 2014. A study of the native cell wall structures of the marine alga Ventricaria ventricosa (Siphonocladales, Chlorophyceae) using atomic force microscopy. Microscopy. DOI: 10.1093/jmicro/dft083

Preston, R. D.; Astbury, W. T. 1937. The structure of the wall of the green alga Valonia ventricosaProceedings of the Royal Society of London, Series B, Biological Sciences122(826): 76-97.

Wikipedia. Valonia ventricosa. Availabe at: < https://en.wikipedia.org/wiki/Valonia_ventricosa >. Access on April 6, 2016.


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Filed under Algae, Botany, Friday Fellow