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I can't see much discussion of the nature of these plants and seems to miss some interesting stuff (unless I missed it), so here's my recollection from reading

I can't see much discussion of the nature of these plants and seems to miss some interesting stuff (unless I missed it), so here's my recollection from reading around. The 'trees' were club mosses, not trees. Moss as in moss in the usual sense, except got big. One common sort was lepidodendron (https://en.wikipedia.org/wiki/Lepidodendron https://en.wikipedia.org/wiki/Lepidodendron). Note the distinct scale pattern on the trunks. Absolutely fascinatingly to me, the descendents of these may still exist as quillwort (https://en.wikipedia.org/wiki/Isoetes https://en.wikipedia.org/wiki/Isoetes).

kragen 7y ago
"Tree" is a paraphyletic taxon; today you have conifer trees, angiosperm trees, cycad trees, and so on, all of which are more closely related to non-tree plants than to each other. Even among angiosperms, you have lots of different trees that are more closely related to non-trees than to each other — a black locust tree is more closely related to a soybean plant than it is to an apple tree. So there's no reason to claim that a club-moss tree isn't a tree. Bamboo, maybe you would have a point, but not club-moss trees. https://en.wikipedia.org/wiki/Tree https://en.wikipedia.org/wiki/Tree
- tempguy9999 7y ago
  Very good points, thanks. I know that legumes fall into their own group so if a locust bean is a legume then naturally it must be more closely related to soybean vines than an apple - but I just never thought of it that way. A rather new perspective. Personally I wouldn't class a cycad as a tree, nor a date palm, and I wouldn't call a lepidodendron one either, but after a bit of reflection I've no good reason to take that view, so thanks for all this!
  - kragen 7y ago
    Note that “dendron” is usually translated to English as “tree” but of course that's a pretty weak argument—there's no requirement that words in different languages denote precisely coextensive categories.

kragen 7y ago

"Tree" is a paraphyletic taxon; today you have conifer trees, angiosperm trees, cycad trees, and so on, all of which are more closely related to non-tree plants than to each other. Even among angiosperms, you have lots of different trees that are more closely related to non-trees than to each other — a black locust tree is more closely related to a soybean plant than it is to an apple tree. So there's no reason to claim that a club-moss tree isn't a tree. Bamboo, maybe you would have a point, but not club-moss trees. https://en.wikipedia.org/wiki/Tree https://en.wikipedia.org/wiki/Tree

tempguy9999 7y ago
Very good points, thanks. I know that legumes fall into their own group so if a locust bean is a legume then naturally it must be more closely related to soybean vines than an apple - but I just never thought of it that way. A rather new perspective. Personally I wouldn't class a cycad as a tree, nor a date palm, and I wouldn't call a lepidodendron one either, but after a bit of reflection I've no good reason to take that view, so thanks for all this!
- kragen 7y ago
  Note that “dendron” is usually translated to English as “tree” but of course that's a pretty weak argument—there's no requirement that words in different languages denote precisely coextensive categories.