Plants in the bedroom

Bill Williams bwilliam at
Tue Feb 21 14:10:29 EST 1995

In article <3iba7f$p5a at>
onedolphn at (OneDolphn) writes:

> Plants ALWAYS breathe in CO2 and give off oxygen...I've had plants in my
> bedroom for years, and they are all doing fine!

Well, no.  Plants, like all aerobic organisms, ALWAYS breathe in oxygen
and give off CO2:  you got it backwards.  However, when there is enough
light some parts of the plant (usually the leaves) ALSO "breathe" in
CO2 and give off oxygen.  Obviously (since plants do grow) the overall
balance is in favor of photosynthesis (taking in CO2 and giving off

Many botany textbooks note the myth of plants' poisoning the air,
usually crediting it to Jan Ingenhousz, who discovered in the early
18th century that plants gave off "bad air" (just like animals) in the
dark.  J. B. Priestly had previously noted that plants "restored" air,
but he only did his experiments in the light (easier to see what you're
doing that way).  Apparently Ingenhousz did actually advise hospitals
to remove plants from patients' rooms.  There is a good review of the
early history of photosynthesis in Gest, H. (1988) Sun-beams,
cucumbers, and purple bacteria.  Photosynthesis Research 19:287-308.
(Reference in Salisbury and Ross (1992) Plant Physiology.)
Bill Williams
bwilliam at
Dept. of Biology
St. Mary's College of Maryland
St. Mary's City, MD 20686 

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