Clearing
heat in Chinese medicine is
a deep concept:
http://sixfishes.com/learn/edu/using-heat-clearing-herbs-to-calm-the-spirit Basically, it refers to
calming down psychologically and treating irritations and similar
conditions. Different herbs
can be used for that purpose, starting with
valeriana:
https://herbalref.com/valeriana-valerian-root-valerianae-radix/
, but also melissa and other herbs with similar effect.

thank you, diane. so it doesnt mean that the plant will slow down perspiration or subjective feelings of heat?

Coby - No ... the heating and cooling refers to the metaphysical way they define things, not actual cooling.

I believe lemon balm is also supposed to be good for this; very useful in Pennsylvania, where it grows very freely and can even naturalize.

some inaccurate info has been offered here.

Heat Clearing per chinese medicine does refer to actual cooling and clearing of pathogenic Heat.....which can be actual heat, inflammations, etc. Also, valerian is a warming herb so it can and often does exacerbate heat signs in those who tend to run warm. (I can't take it for example)

Common cooling/heat clearing herbs include most mints like lemon balm and spearmint as well as most flowers used as herbs like hibiscus, chrysanthemum, rose, etc. push heat out thru the skin, they make us sweat to cool us down. Also very bitter herbs like gentian, coptis, etc. drain Heat and energy downward and out of the body.