Molecular Abundances in Late Spectral Type Stars
(The statements below summarize and explain the trends seen in the previous two visuals.)

(1) Most molecules become progressively more abundant as T decreases.

(2) There are several notable exceptions to (1), especially CN, CH and C₂ which decline after reaching a peak because
     most C tends to become tied up in CO and CO₂ and therefore unavailable to form other carbon-bearing molecules. 
     (These exceptions occur in stars of normal abundances which have N(O) > N(C).)

(3) In carbon stars (which have N(C) > N(O)) most of the O-bearing molecules decline in abundance after reaching a peak
     because most O tends to become tied up in CO and CO₂, (i.e., the roles of O and C are exchanged).

(4) Especially at higher temperatures, most molecules tend to be more common in dwarfs than comparable giants because
     of higher atmospheric pressures.