The Two Yin-Nourishing "Dong" Herbs: Maidong and Tiandong

Doctor zhou
Maidong (Ophiopogon) and Tiandong (Asparagus) are both Liliaceae plants. Maidong is the dried tuber root of Ophiopogon japonicus, and Tiandong is the dried tuber root of Asparagus cochinchinensis. The tuber roots of these two related plants look similar, their medicinal natures are similar, and both are commonly used TCM yin-nourishing herbs.
Maidong is sweet and slightly bitter, slightly cold in nature, entering the Heart, Lung and Stomach meridians. It nourishes yin and moistens the lung, benefits the stomach and generates fluids, and clears the heart and relieves vexation. It is commonly used for: 1. lung-dryness dry cough, yin-deficiency consumptive cough, and throat impediment and sore throat; 2. insufficient stomach yin, thirst from fluid impairment, internal heat wasting-thirst, and intestinal-dryness constipation; 3. heart-yin deficiency and warm-disease heat disturbing the heart construction, with vexation and insomnia.
Tiandong is sweet and bitter, cold in nature, entering the Lung and Kidney meridians. It nourishes yin and moistens dryness, clears the lung and generates fluids. It is commonly used for: 1. lung-dryness dry cough, paroxysmal cough with sticky sputum, and consumptive cough with blood; 2. kidney-yin deficiency with sore and weak lower back and knees, and steaming bone and tidal fever; 3. internal heat wasting-thirst, fluid damage from febrile disease, dry throat and thirst, and intestinal-dryness constipation.
Judging by their flavors, natures, meridian entry and functions, Maidong and Tiandong share much in common. Both enter the Lung meridian, both nourish yin and moisten the lung, and both treat lung-dryness dry cough. For lung-kidney yin deficiency with lung-dryness cough, the two are often used mutually reinforcement. The Zhangshi Yitong contains a formula called "Erdong Gao" (Two-Dong Paste), made by equal parts of Tiandong and Maidong boiled into a paste; it treats consumptive cough with blood from dryness evil injuring the lung or yin-deficiency lung cough, or dry cough with sticky sputum and blood in the sputum.
Tiandong and Maidong also both treat internal heat wasting-thirst, fluid damage from febrile disease, dry throat and thirst, and intestinal-dryness constipation, because both have good yin-nourishing effects. Maidong is more often used for internal-heat wasting-thirst caused by stomach heat; the famous warm-disease formula Zengye Tang is composed of Xuanshen, Maidong and Shengdi, and works well for no bowel movement for several days due to Yangming warm disease or for intestinal-dryness constipation in the elderly. Tiandong, by contrast, is better at internal-heat wasting-thirst caused by lung heat; it both clears lung heat and nourishes lung and kidney yin. For treating fluid damage from febrile disease it is often combined with Renshen and Shengdi, or with Shengdi, Danggui and raw Heshouwu.
It is generally held that Tiandong is stronger than Maidong at clearing lung heat and nourishing lung yin and is a key herb for lung-yin deficiency; modern pharmacology confirms that asparagine has antitussive, expectorant and antiasthmatic effects, and Tiandong decoction also has marked antibacterial action. Tiandong also nourishes kidney yin and treats steaming bone, consumptive fever, night sweats and seminal emission from kidney-yin deficiency. Maidong, by contrast, excels at nourishing the stomach and generating fluids, and clearing the heart and relieving vexation, treating dry mouth and tongue from warm disease or chronic fluid damage, and restless, sleepless spirits from yin deficiency with heat or warm-disease heat entering the construction-blood.
Both Tiandong and Maidong boost immunity and have antitumor effects, and are commonly used for cancer of the yin-deficiency-with-heat type. Both are root-strengthening herbs that help cancer patients raise immunity, but because yin-tonifying herbs are often cloying and obstructive, they are contraindicated in those with spleen-stomach deficiency-cold, poor appetite and loose stools. Cough caused by wind-cold external contraction or by phlegm-dampness should also not be treated with Tiandong or Maidong.

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