Rough Horsetail (Equisetum hyemale)

Let me introduce you to another fascinating Florida native plant- Rough Horsetail (Equisetum hyemale): a vascular plant in the fern family with 41 different species and one extinct species, the Genus Raniganjia. 

What is a vascular plant? Vascular plants form a large group of land plants, over 300,000 species, with lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified tissue (the phloem) to conduct products of photosynthesis. Vascular plants include the clubmosses, horsetails, ferns, gymnosperms (including conifers), and angiosperms (flowering plants). Vascular plant – Wikipedia

Xylem: the vascular tissue in plants that conducts water and dissolved nutrients upward from the root and also helps to form the woody element in the stem.

Phloem: the vascular tissue in plants that conducts sugars and other metabolic products downward from the leaves.

Despite the diversity of horsetails, paleobotanical studies (the study of fossil plants) have demonstrated that the genus Equisetum is the sole surviving representative of an ancient and diverse group, the Sphenopsida (a class of pteridophyte plants that comprises the horsetails and their extinct relatives). These particular species of horsetails have fossils dating back to the Devonian period, that’s over 400 million years ago!

Elgorriaga, A., Escapa, I. H., Rothwell, G. W., Tomescu, A. M. F., and Rubén Cúneo, N.. 2018. Origin of Equisetum: Evolution of horsetails (Equisetales) within the major euphyllophyte clade Sphenopsida. American Journal of Botany 105( 8): 1286– 1303.
Rough Horsetail. Photo by Alice Mary Herden

Horsetails produce either fertile or sterile plants. Fertile horsetails have one stem containing the spore cones located at the tip of the stem. These typically form during the spring season. Sterile horsetails have jointed segments around the sections of the nodes. 

I added some links for further reading at the end of this post. 

At first look, horsetails look like bamboo, and just like bamboo, these upright stems have a monopodial branching pattern. Monopodial is a growth habit in plants that grow upward from a single point. There’s a lot more terminology on that, but we will skip it and move on and talk about some of the cool stuff.

A couple of neat things about horsetails are one, these plants are hollow, like a straw, and the segments of the plant pop out. Remember those pop beads we all had when we were toddlers? Like back in the dinosaur age, horsetails are like that. The stem is a long, tall pop-out plant. And what is super cool is once a segment is detached, the base of the node will close entirely within 24 hours. 

Rough Horsetail. Photo by Alice Mary Herden

The question is- While we may know why the plant instinctively closes after it has been detached (the nutrient supply is cut from the primary source- the root), but what is the purpose of that, and how does it close? 

If I get the answers to those questions, I will update this post.

While horsetails are found in swamps, marshes, and river banks, it is an aggressive but functional Florida native plant. There is a debate whether or not wildlife forages on these plants. However, these plants do provide excellent coverage for many species of wildlife. 

I will be back to visit this plant during Spring when the spores are ready; until then, enjoy viewing these plants in the wild.

Remember, you may think you researched everything about your subject, yet you will discover so much more. 


Links:

https://plants.ifas.ufl.edu/plant-directory/equisetum-hyemale/

Great video on Horsetails!

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