View photos of the medicinal plant Pinus leiophylla var. chihuahuana (Chihuahua pine), profiled in Medicinal Plants of the Western Mountain States (as Pinus spp.).

A passage from Medicinal Plants of the Western Mountain States:

As part of a formula, oleoresin tincture imparts a stimulating–antimicrobial influence. After ingestion, the oleoresin’s aromatic terpenes are secreted/excreted into the bronchial environment. Here they serve to loosen thickened bronchial mucus and inoculate the surrounding airspace/lung tissues with antimicrobial volatiles. Coughing become more productive and any potential bacterial (and likely viral) growth is inhibited. Formulated as a syrup ingredient (10%–25%), the oleoresin tincture complements cough suppressants like Wild cherry or Pleurisy root very well.