Warm Acrid Herbs that Release the Exterior

What are the entering channels of Ma Huang (ephedrae herba)?

The Lung governs the exterior, and Ma Huang releases the exterior, so Ma Huang enters the Lung channel. Ma Huang also stops cough, which is another reason it enters the Lung channel. And then, Ma Huang promotes urination to treat edema, so it enters the UB channel. The UB channel is also the most exterior channel, and Ma Huang treats Tai Yang excess patterns.

Source: Bensky, D. (2004). Chinese Herbal Medicine: Materia Medica. Seattle, WA: Eastland Press. p. 4 [Q313]