All gaseous waste in plants exit through

All gaseous waste in plants exit through Stomata.

Explanation:

The excretion of various gases in plants will indefinitely occur through what is called as stomata. These stomata have pores through which the gaseous exchange takes place.

Plants excrete oxygen during photosynthesis and carbon dioxide through the process of respiration. Stomata are nothing but extremely small pores that are mostly found on leaves but some may be found on stems as well.

There are specials cells called the guard cells that are structured in a way that they control the opening and also closing of these pores. Almost all the stomata are found on the downside surface of leaves thereby are protected from major heat loss. Only in aquatic plants, they are mostly found on the upperside.  

not sure if this is what you'r looking for prokaryotes have organelles hope this out at least.