I was under the impression that structural lignin was what really made trees a viable style of growth, and that seems like an odd chemical for a bunch of unrelated plants to all evolve. Is there something I’m missing? Is lignin actually present in all vascular plants?
I wasn’t being specific enough. Cell walls in plants are composed of cellulose, hemicellulose, and lignin. Lignin IS one of the structural polymers that plants produce, and yea, every single vascular plant has and uses lignin to provide structure. Iirc its a polymer produced by every plant, including mosses and other nonvascular plants, it’s just not used to the same extent.
Yea, the evolution of vascularity in plants let them get off the ground in the first place (meaning being taller than a few inches). Vascularity is the first big jump plants made after leaving the water. From there, being taller means outcompeting your neighbors and spreading your babies further. When you have that double whammy of more food + more babies, you get a selective pressure for taller that never really goes away. This is why multiple families have species that have arborized and have continuously done so over their evolutionary history. If the niche is empty, something will jump into it, often sooner rather than later (on a deep time scale) which is basically the whole idea of convergent evolution as a whole.
I was under the impression that structural lignin was what really made trees a viable style of growth, and that seems like an odd chemical for a bunch of unrelated plants to all evolve. Is there something I’m missing? Is lignin actually present in all vascular plants?
I wasn’t being specific enough. Cell walls in plants are composed of cellulose, hemicellulose, and lignin. Lignin IS one of the structural polymers that plants produce, and yea, every single vascular plant has and uses lignin to provide structure. Iirc its a polymer produced by every plant, including mosses and other nonvascular plants, it’s just not used to the same extent.
AH, I see. So, it already existed, but until trees evolved, it wasn’t used to such an extreme extent.
Yea, the evolution of vascularity in plants let them get off the ground in the first place (meaning being taller than a few inches). Vascularity is the first big jump plants made after leaving the water. From there, being taller means outcompeting your neighbors and spreading your babies further. When you have that double whammy of more food + more babies, you get a selective pressure for taller that never really goes away. This is why multiple families have species that have arborized and have continuously done so over their evolutionary history. If the niche is empty, something will jump into it, often sooner rather than later (on a deep time scale) which is basically the whole idea of convergent evolution as a whole.