Can I backbreed Horsetails Into Tree-Sized Versions?

[ralph124c]

The common horsetails in my garden are only a few inches tall-in carboniferous times, they were as big as trees. Do the modern ones contain the essential genetic material, which would enable them to be as big again? Why has such an (apparently) successful species chosen to evolve to such a small size? As far as i know, these things have no natural enemies-do modern bugs eat them?

[Polycarp]

1. If I remember right, there are living species in tropical America that grow to the height of small trees, though the families of tree-size Sphenopsids from Paleozoic times are now extinct. I suspect climate may have quite a bit to do with it – a warm-year-round, moist, CO[sub]2[/sub]-rich atmosphere would promote growth. Despite the Fens, Boston is not exactly the climate of the Carboniferous swamps.

2. Sphenopsids were successful in competition with Psilophytes, which look for all the world like leafless greenish twigs, and mosses and liverworts, which were not adapted for size. But they lacked some of the essential characteristics that enabled ferns, gymnosperms, and especially angiosperms to dominate the world’s flora in later eras. (Without a good textbook on evolutionary botany at hand, I’ll leave it at that nebulous statement – but ther are some good detailed reasons I don’t recall or have at hand underlying my glittering generality.)

3. They have pegged out a niche for themselves where they can compete, and cling tenaciously to it. One adaptation worth noting is that they use silicon compounds for protection and structural strength. I’m not sure what if anything eats them; I used to notice them as common along railroad tracks in my old hometown, and grasshoppers used to be very prevalent on and around them. Whether that’s a feed-on-them relationship I don’t know.

[Duck_Duck_Goose]

Grizzly bears and other herbivores eat horsetail.

Equisetum arvense.
http://www.fs.fed.us/database/feis/plants/fern/equarv/all.html

Field horsetail is a common food item consumed by grizzly bears [37].
On average, field horsetail formed 2.4 to 5.2 percent by volume of the
grizzly bear summer diet in Yellowstone National Park and was ranked
10th out of 32 food items in amount of consumption [49]. Field
horsetail occurs in the wet meadows, marshes and moist cirque basins
most often visited by grizzly bears in spring [2]. Field horsetail is a
minor to important component in the spring and early summer diet of
black bears [28,32]. It is of low nutritive value [49].

Field horsetail is not an important range forage for livestock, and
excessive amounts (more than 20 percent) in hay can cause scours,
paralysis, and death in horses [36].
PALATABILITY :
Field horsetail is low in palatability to livestock, deer, and elk [39].

Equisetum sylvaticum.
http://www.fs.fed.us/database/feis/plants/fern/equsyl/all.html

IMPORTANCE TO LIVESTOCK AND WILDLIFE :
In interior Alaska, horsetails (Equisetum spp.) comprise the largest
component of the spring diet of black bears. Horsetails and blueberries
(Vaccinium spp.) are the two most important plant genera to black bears
in the region [20].

So modern horsetails co-evolved with mammalian herbivores.

[Sunspace]

My first thought on reading the OP was, “How much time do you have?”

[Mangetout]

I wonder how closely related they even are - it could be the same sort of genetic/taxonomic/phylogenetic distance between the tree-horsetails and the modern ones as it is between, say, two modern members of the rose family so the question might be analogous to asking “can I breed apple(or some kind of) trees from strawberry plants?” - to which the answer would be ‘yes, if you’re immortal, and patient’.

Trees or tree-like plants have evolved independently many times - so it’s not impossible that it could happen again.