C3 vs C4 vs CAM

	C3	C4	CAM
In hot areas	Cons: shut their stomata (stopping CO2 entry) and increase photorespiration as temperature increase	Pros: overcome the tendency of photorespiration by using a more efficient enzyme to fix CO2 in and shuttles fixed carbon via malate or aspartate to bundle-sheath cells. In these bundle-sheath cells, RuBisCO is isolated from atmospheric oxygen and saturated with the CO2 (released by decarboxylation of the malate). Cons: additional steps, however, require more ATP.
Examples	most small seeded cereal crops such as rice (Oryza sativa), wheat (Triticum spp.),  barley (Hordeum vulgare), rye (Secale cereale), and oat (Avena sativa);  soybean (Gycine max), peanut (Arachis hypogaea), cotton (Gossypium spp.), sugar beets (Beta vulgaris), tobacco (Nicotiana tabacum), spinach (Spinacea oleracea), potato (Solanum tuberosum)	Corn	Pineapple, agave
Pros	More efficient than under cool and moist conditions and normal light because requires less machinery (fewer enzymes and no specialized anatomy)	Fast growing in warm/dry areas Minimize photorespiration Photosynthesizes faster than C3 plants under high light intensity and high temperatures because the CO2 is delivered directly to RUBISCO, not allowing it to grab oxygen and undergo photorespiration. Has better Water Use Efficiency because PEP Carboxylase brings in CO2 faster and so does not need to keep stomata open as much (less water lost by transpiration) for the same amount of CO2 gain for photosynthesis.	Fast growing in hot/dry areas Minimize photorespiration Fix CO2 at night Better Water Use Efficiency than C3 plants under arid conditions due to opening stomata at night when transpiration rates are lower (no sunlight, lower temperatures, lower wind speeds, etc.). When conditions are extremely arid, CAM plants can just leave their stomata closed night and day. CAM-idle: Oxygen given off in photosynthesis is used for respiration and CO2 given off in respiration is used for photosynthesis. This is a little like a perpetual energy machine, but there are costs associated with running the machinery for respiration and photosynthesis so the plant cannot CAM-idle forever. CAM-idling does allow the plant to survive dry spells, and it allows the plant to recover very quickly when water is available again (unlike plants that drop their leaves and twigs and go dormant during dry spells).
Cons		Needs more ATP	Stomata open only at night
Enzyme	Rubisco	Pep carboxylase	Pep carboxylase