Which plant uses the most carbon dioxide?

Question

Is there a plant that uses a higher percentage (related to mass) than the usual or is it mostly just related to mass, since the carbon builds plant mass? Thanks.

Answer 1

I suspect that it is unlikely that different plant species differ very much in relative carbon content (i.e. grams C per gram dry weight).  Photosynthesis is the sole route for entry of all but a few mineral constituents of the plant.  Thus, more than 99% of the plant weight can be considered a product of photosynthesis.  Most of this dry matter is composed of carbon, oxygen, and hydrogen in the relative ratio of 1:1:2.  Certainly these elements undergo a great deal of redistribution among the various organic constituents but the relative ratio does not change much during metabolism.  Respiration does not change this picture since it produces CO2 and H2O in the same proportion that photosynthesis takes up these compounds.