Tag Archives: Pteridophyta

Friday Fellow: Mexican Giant Horsetail

by Piter Kehoma Boll

If you are walking through the forest of Central America, you may end up finding something that at first you could think is a group of bamboos, plants growing as a cylindrical segmented stem that can reach up to 7 m in height, as seen in the picture below:


A group of bamboos? Not exactly. Photo by Alex LomasAlex Lomas.*

Those are not actually bamboos, though, but specimens of the largest species of horsetail that exists today, the Mexican giant horsetail, Equisetum myriochaetum. It can be found growing naturally from Peru to Mexico in areas of fertile soil, especially along water bodies such as streams and swamps.

As other horsetails, the Mexican giant horsetail has an erect and hollow stem with very narrow leaves growing in a whirl around the “joints” of the stem. The leaves are very simple, similar to those of more primitive plants such as the spikemosses and ground pines, but are thought to be a simplification of more complex leaves, as they are more closely related to the complex-leaved ferns.

More than only the largest horsetail in the world, the Mexican giant horsetail is an important medicinal plant in Mexican folk medicine, being used to treat kidney diseases and type 2 diabetes mellitus. And as in many other occasions, laboratory studies confirmed that water extracts from the aerial parts of E. myriochaetum do indeed reduce the blood glucose levels of type 2 diabetic patients without reducing their insulin levels. One more point to traditional medicine.

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EOL – Encyclopedia of Life. Equisetum myriochaetum. Available at <http://eol.org/pages/6069616/overview&gt;. Access on March 4, 2017.

Revilla, M., Andrade-Cetto, A., Islas, S., & Wiedenfeld, H. (2002). Hypoglycemic effect of Equisetum myriochaetum aerial parts on type 2 diabetic patients Journal of Ethnopharmacology, 81 (1), 117-120 DOI: 10.1016/S0378-8741(02)00053-3

Royal Botanic Garden Edinburgh. Equisetum myriochaetum. Available at <http://www.rbge.org.uk/the-gardens/plant-of-the-month/plant-profiles/equisetum-myriochaetum&gt;. Access on March 4, 2017.

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Friday Fellow: Samambaiaçu

ResearchBlogging.orgby Piter Kehoma Boll

It’s more than time to bring a fern as a Friday Fellow, and I decided to start with one of my favorites, the Neotropical tree fern Dicksonia sellowiana, known in Brazil as Samambaiaçu or Xaxim.


A samambaiaçu in a forest in southern Brazil. Photo by Wikimedia user DeadWood II.*

The samambaiaçu occurs from southern Mexico to Uruguay and is usually found in moist forests, being a remarkable species of moist forests in southern Brazil, especially in Araucaria moist forests. It may reach several meters in height and the fronds (leaves) reach up to 2,4 m in length.

During most of the 20th century, the fibrous stems of the samambaiaçu (usually called “xaxim”) were extensively used for manufacturing flower pots or plates that served as a substrate for cultivating orchids and other epiphytic plants. As a result of this exploitation, as well as the destruction of its native habitat, the samambaiaçu is currently included in the Brazilian Red List of endangered species.

The trade of xaxim is currently forbidden by law in Brazil, so if  you ever find someone selling it somewhere, please, communicate the authorities!

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Schmitt, J., Schneider, P., & Windisch, P. (2009). Crescimento do cáudice e fenologia de Dicksonia sellowiana Hook. (Dicksoniaceae) no sul do Brasil Acta Botanica Brasilica, 23 (1), 283-291 DOI: 10.1590/S0102-33062009000100030

Brazil. Law Nº 9.605/98. Available at: <http://www.planalto.gov.br/ccivil_03/leis/L9605.htm >.

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