The Great Horsetail – Backyard Discoveries


Equisetum telmateia. Great horsetail.
We are here in Seattle Washington in a greenbelt and we’re gonna wander around to see if there’s some cool plants that we can learn some cool stuff about
so we have well big leaf maple is pretty neat it’s one of the most dominant
species around here it’s actually experiencing a bunch of herbivory which
if we could find the culprit of the herbivory would be pretty interesting
but I’m not sure that we’re gonna do that today see what else we have
himalayan blackberry introduced species from possibly the Himalayas but possibly
not look what we got here well I know this is horse tail I don’t really know
much more about it than that but I just as a kid knew that this was always
called horse tail so let’s look into that so we knew that this was horsetail and
we looked into it a little bit and we pretty quickly found that in the whole
world there’s only one genus of horse tails and genus is just sort of a level
of identification that’s between species and family so all that exists now is one
family of horse tails and within that there’s one genus which is equisetum
and we looked up over a few resources like iNaturalist and the herbarium
records here in Washington and there’s a handful of species here but there are
only two that really look like this there was giant horsetail and there was
field horse tail and just by the fact that these ones are so tall we know that
this one is giant horsetail. So how do horce tails grow and reproduce? Horse
tails can reproduce by multiple ways so first is by producing spores horse tails
are not seed plants like most plants you’re used to they produce spores like
in the same way that mosses and ferns do but they can also reproduce by their
roots or what’s called their rhizomes so they basically just send out roots and
then another individual will pop up and because of that it explains why there’s
this big mass of them all in one place and you see really dense packs of plants
that often is an indication that they’re reproducing by their roots in some way
and you can actually tell by the way they look whether they’re reproducing by
spores or by their roots so in this species when they’re reproducing
asexually or just through the roots they produce these big long leaves like this
but if they were reproducing by spores they produce a single stalk that looks
kind of like a like a sprig of asparagus that has a sporing body on the top. Do
you have any random history tidbits about these? Horse tails actually played
an interesting part in mathematics where in the 1700s John Napier was looking at
horse tails and he saw that the segments down low in the plant between each
cluster of leaves were farther apart and as they got towards the top of the plant
they got closer together but not in a sort of consistent linear fashion and
his observation of that inspired him to invent the mathematics of logarithms Do they have any functional uses for
humans? Horse tails have high levels of silica which is this sort of like sandy
glassy like substance and it’s been used by people Aboriginal peoples as an
abrasive and it’s also used today by woodworkers they’ll grind it up and it
can get wood smoother than any other sandpaper. How about their evolutionary
history? Horse tails are what’s often called a living fossil which means
they’re distantly related from any plant that exists today in fact 100 million
years ago they were one of the most abundant types of plants on the
planet and there were huge ones like 30 feet tall that were just called trees
now there’s only smaller ones and you know there were probably hundreds of
species 100 million years ago but now there’s only 15 we just barely scratched the surface
with backyard discoveries there’s a ton more to learn out there and if you are
interested in horse tails we encourage you to do independent research there’s a
lot more to learn on that topic as well we will be back in the future with more
episodes so keep your eyes peeled for that thanks for watching and we will see
you next time

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Reader Comments

  1. Robyn Grainger

    Hi! Informative video, thank you!
    I have a question, to which I have yet to find an answer..
    In our local wild hedgerows, I have found a lot of a particular plant, which has a lot of similarities to the great horsetail, however, it is much shorter, grows only up to about 2-3 feet,the spines (?) Are shorter and much more compact than this, but has the same hairyness to it and sectioned stem like this.Do you have any idea what it might be? Thanks!

  2. Rheiner Hiss

    Hello, might you be able to tell me where I can purchase this plant to grow? I live on the east coast and I would like to grow it and teach others about its ancient roots dating back to the Carboniferous period…

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