Willowherb (Za Cao)Willowherb (Za Cao)

Botanical Name: Epilobium augustifolium

Willowherb (also called Willow Herb) is not to be confused with the Willow Tree (also called Willow White). Willowherb is a lovely plant known mostly for being nutritious and edible, but it is also a good medicine for treating whooping cough and asthma. It is often used with the herb saw palmetto to treat prostrate problems. It is known for its ability to treat urinary tract infections, chronic diarrhea, intestinal irritations, and skin problems ranging from eczema, acne and burns to wounds and boils. The juice of the flowers is highly antiseptic and can be simply squeezed from the fresh petals.

Below is an overview of Willowherb (Za Cao), combining and interpreting the best of Western Science, Traditional Chinese Medicine (TCM), Shamanism, Folklore and more. Gain a balanced and thorough understanding of the healing properties of Willowherb (Za Cao).

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Western Name: Willowherb

Also Known As: Fireweed, Rosebay Willowherb, Spike-primrose, Boisduvalias, French Willow, Blood Vine, Wickup, Tame Withy, Blooming Sally.

Organs/Systems: Lung, Bladder, Prostrate

Key Western Actions & Medicinal Uses: Demulcent, Tonic, Astringing, Antispasmodic, Mucilage, Anti-inflammatory.


Pin Yin: Za Cao

Also Known As: N/A

Meridians: Lung, Kidney

Key TCM Actions & Medicinal Uses: Clears Heat/Resolves Phelgm: colds, asthma, coughs.  Seeds used to Tonify Kidney Qi and Yang: impotence.

Basic Habitat/Botany:

A genus in the Onagraceae family, containing about 160-200 species of flowering plants. Willowherb is a herbaceous plant that can either be annual or perennial, and a few are sub-shrubs. The leaves are mostly opposite or whorled, simple and ovate to lanceolate in shape. The flowers are usually smallish and pink, but a few species are red, orange or yellow. The fruit is a slender cylindrical capsule containing many seeds, embedded a in fine, soft, silky fluff, that are dispersed by wind. The plant blooms for only a month.

Willowherb is native to North America and Europe with nine species native to Great Britain. Generally found in subarctic, temperate and subantartic regions. Willowherb is quick to carpet large swathes of ground and may dominate an ecosystem. Most will not tolerate shade trees and prefer recently disturbed patches, yielding to other plants over time.

Willowherb (Za Cao) Parts Most Frequently Used: Leaves, Roots, Young Shoots, Seeds

Flavors/Temps: Bitter, Astringing

Caution: Infusions of leaves can be too bitter causing stomach disorders.

History/Folklore: Willowherb is often considered a weed in the garden. In WWII, it rapidly colonized derelict bomb sites during the many bombings of London. In America, it springs up on ground recently cleared by fire, lending it the name of “fireweed.” It has also been known to colonize sites disturbed by oil spills and so is often used to re-establish vegetation in these areas.

The young leaves, roots and shoots are edible, with the shoots being eaten like you would eat asparagus.  The dried leaves make a good tea.

As fodder it is popular with goats and cows and sheep will eat it too.  It is believed in Finland to increase the milk production of cattle.

The down of the seeds has been mixed with cotton or fur in the manufacturing of stockings. Willowherb has been used in Russia as a tea substitute.

Native American Indians prepared a tea from the root to use as an enema to treat infant constipation. The peelings off the stems were dried and used to make strong cords for fishing.

Willowherb is emotionally considered useful for treating stress, the feeling of being burned out and for washing away an old way of life.

In China, typically only the seeds are used for treating Kidney Qi and Yang.

The name of the genus, Epilobium derives from the Greek words, “epi” meaning upon and “lobos,” meaning a pod, from the fact that the flowers stand upon the top of a long, thin, pod-like seed-vessel.

Key Constituents:

Rich source of Tannins and Vitamins A and C. Mucilage. Bioflavonoids, Pectin, Potassium.

Did you know?

Fireweed, a sweetner?

Willowherb (also called Fireweed) is used as a sweetner in Northwestern North America, where it is put in candy, jellies, ice cream and syrups.


A Rich, Spicy Honey

In late summer, willowherb’s flowers yield pollen and copious nectar which make a rich, spicy honey.

Fun fact!

An Anti-inflammatory

Native American Indians applied the sap from the stem to wounds, making use of the plant’s anti-inflammatory properties.


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