[joha4270]

I don't really think that's a fair assessment, since most of it is in the core. That's some very long and heat resistant roots.

I also can't help but wonder, could trees even use iron if it was plentiful in the upper crust? You need a lot of energy to separate iron oxide into elemental iron. Betting against what evolution can make is usually a bad idea, but that would be a neat trick.

[Anotheroneagain]

Both iron and titanium are ubiquitous in the crust. I think they are the 4th and 9th most common elements, and definitely far more common than carbon.

[shiroiushi]

Yeah, but plants don't normally pull carbon out of the ground; they get it from the air.

[lazide]

No reason they couldn’t, if it was advantageous for them though.

[simmo9000]

Umm... https://en.wikipedia.org/wiki/Biological_carbon_fixation.

[lazide]

What is your point exactly?