Division of labors

The horsetails outside my bedroom window are small and delicate. Along the highway north, though, they're tall and fat, covered with their tiny "flowers" with stubby petals. A different species: at home, they're field horsetails, Equisetum arvense; in the wild, they're giant horsetails, Equisetum telmateia, var. braunii.

Horsetails do not have flowers, nor do they make seeds; rather, they produce spores in little buttons, like the ferns. In the ferns, these "buttons" are on the underside of the leaves. The horsetails grow a fertile head dedicated entirely to spore production. (Called a strobilus.)

Horsetail patch. Sterile stems, spore producing stems.

The spore-producing stems show up first. As the spores ripen, the sterile stems start to grow. For now, they're about 45 cm. tall; they will grow to a couple of metres tall by mid-summer.

The fertile stems, though they have a bit of green in the stem itself, do not "feed"; they're not photosynthetic. Once the spores ripen, these stems will die. The new, green, bristly stalks will do the work of transforming sunlight into food.

Fertile stem, with sporangiophores. Not really flowers.

On this stem, the only leaves are the brown tips of the sheaths that circle the stem at intervals.

Stem with sporangiophores arranged in spiral rows..Click to zoom in and see them.

And here are the "flowers": stubby tacks with many miniature, round "petals".

A young sterile stem. The branches will spread out horizontally as the stalk grows.

This species was the most preferred Equisetum species of coastal native peoples as an important springtime vegetable. The young fertile and vegetative shoots were picked, de-sheathed and eaten raw. However, this genus has been known to be poisonous to livestock and humans if eaten in large quantities. Some native peoples also picked the tops of these plants, boiled them, and drank a glassful of the liquid to cure a urinary ailment. E. telmateia was one of the many Equisetum species used as medicine to treat burns; the stems were burned and the ashes applied to the wound. The silicon dioxide crystals make Equisetum species great scouring tools. Native peoples used them extensively for smoothing and polishing wood and soapstone. In fact, modern-day hunters and outdoors people still use them as scouring utensils for cleaning pots and pans. (Joseph Maser, Indiana U.)

I can't imagine eating these! They're scratchy, even to hold.

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Hay varias especies de cola de caballo (Equisetum sp.). Junto a mi casa, son pequeñas; son Equisetum arvense, la cola de caballo campestre. Al lado de la carretera hacia el norte, son grandes, gordas, fuertes: Equisetum telmateia, la cola de caballo gigante.

La cola de caballo no produce flores. Como los helechos, se propagan por medio de esporas que se hallan en "botones"; en los helechos estos se encuentran en la parte inferior de la hoja. La cola de caballo lleva una cabeza (llamada estrobilo) llena de estos esporangióforos.

Hay dos tipos de tallos: primero aparecen los tallos fértiles, con sus esporangióforos. Estos, aunque tienen un poco de verde, no llevan a cabo el fotosíntesis; su única función es producir las esporas. Una vez maduras, el tallo se muere.

Luego surgen los tallos verdes, no fértiles, que trabajan produciendo los azúcares que necesita la planta.

(División de labores. ¡Sin quejas!)

Partes de la cola de caballo: las hojas son las puntas cafés de las envolturas que se ven a lo largo del tallo. Las "agujas" verdes no son hojas: son ramas. Los "botones" o "tachuelas" (esporangióforos) no son flores, y los "pétalos" no son pétalos. Aquí se producen las esporas.

La última foto es un tallo no fértil, todavía sin abrir sus ramas.

(De la cita:) Los nativos comían estas plantas en la primavera; se pelaban los tallos y se comían crudos. Sin embargo, este género es nocivo, comido en grandes cantidades. Algunos nativos hervían las puntas y se tomaban el líquido para curarse de males del tracto urinario. También se usaba para curar quemaduras.

Debido a los cristales de dióxido de silica, se usan estas plantas como papel de lija o trapos de fregar, tanto para pulir madera y esteatita, como para lavar trastes.

¡No me imagino como se come esta planta! Se sienten bien rasposas al primer tacto.

AKA Puzzlegrass

It belongs here; it's a native. It grows enthusiastically in waste places, roadsides, ditches. "They" say it is edible, with caution. Sometimes it's useful; in a campsite, it makes a handy pot scrubber for those fire-blackened camp kettles. Along the edges of my lawn, and under my bedroom window, it's embarrassing, proclaiming to the neighbourhood that I'm not being careful; it's a pest. A pest that refuses to be exiled.

Horsetail. Weirdly fascinating. Beautiful, if I stop to look at it.

Sterile horsetail stems and a wilting, spore-producing strobilus on its own unbranched stem. With a pink and black fly for company.

The spore-producing stems appear first, then die down. The green, branched stems grow tall and hang around all summer. They grow from a rhizome that can be up to 4 metres underground, making them almost impossible to root out. They will thrive where nothing else except dandelions will take root, poking through gravel or cracks in the pavement, pushing aside stones in the drainage channels along the walls, and spreading out from there.

I wondered how far the spores disperse, and what is the mechanism; wind, water dispersal, shooting out under pressure, etc. I looked it up; now I'm itchy.

The spores have four elaters that act as moisture-sensitive springs, assisting spore dispersal through crawling and hopping motions after the sporangia have split open longitudinally. (Wikipedia)

Crawling, hopping? Legless hoppers? Just outside my window? Somehow it doesn't seem proper plant behaviour.

Branched stem. The green parts are the stems.

And these brown fringes are the leaves.

The hollow stems are photosynthetic, but not the leaves.

One of our local species, the giant horsetail, Equisetum telmateia, usually grows around a metre high, or a bit more, but can grow up to 2 1/2 metres in wet conditions, easy enough to find in our rainforest ecology. The ones under my window, field horsetail, Equisetum arvense, are usually just under a metre tall. I tear them all out several times in a summer; they always come right back up.

The whole plant feels rough, sandpapery. Our First Nations people used them for polishing wooden tools; I think I'll try them on my next project.

Fascinating, but NIMBY!

Horsetails. When I find them around my garden, I rip them out mercilessly. Everywhere else, I admire them.

At the edge of Nicholson Park, there is a mound, almost a tiny hill, of soil and trash left over from clearing a parking lot, long ago. Every summer, it is covered by a thicket of mixed blackberry canes and other weeds; I always stop as we pass, to look at caterpillars and ladybugs. Yesterday's honeybee was on a clump of dandelions along the edge. This year, someone has cut down the blackberries. In their stead, a forest of Japanese knotweed is springing up; not a good development.

But before the knotweed gets its full size, horsetails are having a go at colonizing the newly-emptied ground.

Horsetail, dead leaves, dandelion, ladybug. And a bit of blackberry, coming back. It always does.

At this time of year, horsetails take two forms: a green stalk with a series of whorled branches, which will persist until fall, and a short-lived bare stalk topped with a spore-bearing cone. This will die back as soon as the spores are released.

Fertile stem and strobilus on the left, green steriles on the right.

The horsetails are survivors from an ancient earth, smaller than their ancestors, but still maintaining their unique way of life. They are non-flowering, reproducing by spores like mosses, but not related to them, or to any other plants: they are the only remaining genus in their biological family.

The name, horsetail, or Equisetum, (from Latin equus and seta -"horse bristle") describes them well; the branched species look sort of like a horse's tail. The silicates that coat the stems also give them the texture of a horse's tail hairs: stiff and rough, sandpapery. They have been used as scouring material. When you've burnt your meal, cooking over a campfire, look for horsetails. A couple of handfuls will clean your frypan up nicely.

As for the way they're put together, anything we take for granted in "normal" plants is the opposite in horsetails. Look at the photos of the stem and branches. Yes, the green, needle-like things arranged in whorls at the joints of the stem are branches. The leaves are not on the branches, but form tight, papery sheaths around the stems, like a decorative frill, whitish with brown tips. They are not equipped to perform photosynthesis, like the leaves of most plants do. The sterile stems and branches contain chlorophyll and do the work of transforming sunlight into sugars instead. The fertile stems of the field horsetails are non-photosynthetic; these fertile stems consume food, but produce only spores.

Detail, stems, branches and leaves.

Sporulating head of giant horsetail, Mud Bay.

There are two main species in this area; the common or field horsetail, and the giant. Both are similar, but easily distinguished by size alone. The field horsetail grows to about two feet tall, with fertile stems being half that. The giant's fertile stems are up to 2 feet tall, with the sterile stem growing even up to 10 feet.

Spore-bearing heads of giant horsetail, growing through ditch weeds.

And why I won't allow even one to sprout in my yard and garden: not only are the spores good at what they do, starting new plants, but the roots go down forever. (Or up to 20 feet through hard-packed clay; whichever comes first.) When the plants die down in winter, they are not gone. They're biding their time, spreading themselves about, getting ready to shoot up those fertile heads before the weather lures us out into the gardens again. Digging them out doesn't hurt them; a bit of rhizome left in the soil is enough for regeneration.

Ripping out most of the plants won't kill them, either. It's all or none, because the colonies are clones; each one is part of the whole.

Field horsetail, taking over a gravel pile in our vacant lot.

They grow in wet soil, in dry soil, in clay, in gravel. And in good garden loam. They grow even through a layer of heavy rock. For example:

Fertile spore cones of giant horsetail, pushing through the rock rip-rap beside the railroad track at Kwomais Point.

There are a couple of great photos of fertile cones, here, on Dave Ingram's blog.