Mushrooms—Selfish, helpful, and rocket fuel

(Mushrooms in halacha, kabbalah, social criticism, and biology; March 2008)

As Purim and spring approach, shady, wooded areas become wet and warm. This is an ideal time of year to search for mushrooms. Eating wild mushrooms can be extremely dangerous, and is STRONGLY discouraged for anyone but experts in mushroom identification. However, some important lessons can be learned by observing how mushrooms grow and how they are understood in halachah (Jewish law) and kabbalah (Jewish mysticism).

Halachah requires Jews to thank God by reciting the appropriate blessing before using or obtaining material benefit from any object. The Talmud (Berakhot 40b) considers several possible wordings for blessings to be recited before consuming plant products such as fruits and vegetables. The conclusion reached is that two alternative forms should be used: Before consuming tree fruits (including nuts) one should thank God “Who creates the fruit of the tree” (“boray pri ha’etz”). Before eating vegetables, the language used changes to “Who creates the fruit of the earth” (“boray pri ha’adamah”).

What kind of “fruit” is a mushroom? Until the early twentieth century, the Western world viewed the world as composed of three types of objects—animals, vegetables, and minerals (non-living things). This understanding was reflected in the division of living things into two kingdoms—animal and plant—in the classification system developed by the Swedish naturalist Carl von Linne in the eighteenth century. Fungi were included in the plant kingdom. However, as biologists learned more about mushrooms and other fungi, increasing amounts of evidence accumulated that fungi are quite different from plants, and should be placed in their own kingdom. (One contributor to this growing body of knowledge was the naturalist and children’s book author Beatrix Potter, whose connection to Passover was described in Peter Rabbit and Hollywood–The Passover Connection.) Around 1950, a five-kingdom system was developed, with separate kingdoms for animals, plants, fungi, bacteria, and protists (organisms such as amoebas and algae that are more complex than bacteria but have no organs). Some biologists have since proposed dividing living things into even more kingdoms.

It is interesting to note that the Talmud anticipated these developments by well over a millennium. The Talmudic discussion of blessings over fruits and vegetables described above concludes that mushrooms are not part of either category. Instead, the blessing said over mushrooms concludes “according to Whose word all things are created” (“shehakol nih’yeh b’dvaro”).

This catch-all form is used when one is about to consume a food that is not recognizable as derived from part of a plant, such as water, meat, or candy. The Talmud accepts this conclusion, while the practical details are described in later works, such as the sixteenth century codification of halachah, the Shulchan Aruch (Orach Chaim 204:1).

What is the reasoning behind this decision? The Talmud points out that fungi do not obtain nutrients from the soil as plants do, and may also grow without soil (e.g., on live or dead trees), and therefore are not “fruits of the earth”. Several later authorities, including the Mishneh Brurah, a popular modern commentary on the Shulchan Aruch, expand on this explanation. Published in six volumes, from 1894 to 1907, some fifty years before the five kingdom system, the Mishneh Brurah distinguishes between the ability of fungi to extract nutrients from decomposing materials (dead trees and soil organic matter) and the functions of plant roots, which anchor plants in place and absorb only minerals from soil. This insight of the Mishneh Brurah is, in fact, one of the important differences between plants and fungi that led biologists to conclude that these organisms belong in separate kingdoms.

Rabbi Herschel Grossman of Yeshivas Ohr Yosef was kind enough to point out to me that the kabbalah provides a symbolic moral interpretation of the blessing over mushrooms that is especially relevant to Purim festivities. This approach is based on the similarity of the Hebrew words for mushroom or fungus (pitriah) and exempt (patur). The kabbalah supplies a meaning for this similarity: Just as a fungus (pitriah) has no roots that must be anchored in soil, an irresponsible person tries to avoid attachment and commitment, and claims to be exempt (patur) from the demands of life in a society. The impulse to behave in this way is universal—We have all at least occasionally wanted to respond to a request or demand with “It’s not my fault!” or “That’s not in my job description.” As Purim and its carnival atmosphere approach, the spring mushroom crop should give us all pause to consider our actions before we indulge to excess.

From a biological point of view, the connection between pitriah and patur runs quite deep. Plants are the basis of their ecological communities. The solar energy that plants collect through photosynthesis is the source of all the energy used by the animals and other organisms in the area that depend on them. Hence the expression “All flesh is grass.” Fungi, in contrast, are decomposers—organisms that obtain their energy by breaking down dead organisms or animal waste, or by living as parasites on living plants or animals. This is perhaps the closest natural analogy to the ‘patur’ attitude.

A similar idea was expressed by the nature poet Wendell Berry in his book of essays A Continuous Harmony. Berry proposed that one can judge the stability of a rural economy by comparing the land areas it devotes to annual crops (plants that live for no more than one year, such as wheat, corn, rice, and beans) and perennial crops (long-lived plants such as fruit trees). He suggested that planting trees is an expression of a long-term commitment to the future, while planting annuals is attempt to realize a short-term gain, rather than an investment in the future of the land and community. This idea can also be seen in the story of Honi the Circle-Maker, found in Ta’anit 23a. Honi asked an elderly man why he was planting a tree that would not yield fruit until long after his own death. The man replied that he was planting for his children, as his own father had planted for him.

Mushrooms, however, contribute even less than annual plants: They do not perform photosynthesis that would bring solar energy into the community. Mushrooms are raised in the dark, on the waste from other farm operations. Berry might well regard the mushroom farmer as the least valuable member of a farming community. One can certainly take issue with this view. After all, just as annual grain and legume crops have provided the staples that nourished every great civilization, decomposers also perform important ecological functions. They release nutrients from dead material, making them available to plants, and prevent huge accumulations of dead material. Edible decomposers, such as mushrooms, also produce a useful crop from otherwise useless dead material.

If the kabbalah regards fungi as a symbol of selfish irresponsibility, mushroom lovers will be pleased to learn about a more positive contribution that a mushroom may soon make to human welfare. A number of fungi have been found to produce substances with antibiotic or anti-cancer activity. In December of 2007, Dr. Ben-Zion Zaidman of the University of Haifa and his collaborators reported the results of their research on anti-prostate cancer activity in mushroom extracts. The group screened over one hundred fungi for the ability to inhibit the growth of prostate cancer cells and to interfere with the stimulation of the cancer cells by male hormones. The most effective agent was an alcoholic extract of the reishi mushroom (Ganoderma lucidum), a fungus found naturally on rotting oak or plum logs in mountain forests. The process by which the extract works is not yet known. However, methods of growing this wild species that were developed by Japanese mycologists (fungus scientists) in the 1970s may eventually enable scientists to produce a practical treatment for prostate cancer, a disease that appears in over 500,000 men each year. More information about this research is available at:

Some readers may also recall a news announcement on February 21 that the U.S. Navy had fired a missile to destroy an American satellite. The satellite posed a danger of falling to Earth with a fuel tank containing a toxic, explosive rocket fuel called hydrazine. What few people know, however, is that edible mushrooms also contain significant amounts of hydrazine—According to Harold Magee’s classic book On Food and Cooking, as much as 500 parts per million (0.05%). Hydrazine can cause liver damage or cancer in mice, but for some reason, not in rats. Its effect on human health is unclear. Magee states that it is not destroyed by cooking, and recommends that people eat mushrooms only occasionally and in small amounts until the effect of hydrazine on human health is better understood.


  1. The blessing of another year and learning from
    Torah: wintertime becoming spring…

    Dr. Greenberg,
    Thank you once again for this essay and all
    the pleasures in its reading and re-reading,
    too. – Chana

  2. Great article!
    Love mushrooms; didn’t know about the hydrazine.

    Never thought of them as selfish; they very often provide me with delicious flavors, especially when butter is also present.

  3. Selfish? Mushrooms are the only reason that anything grows! They create soil, and they allow plant roots to access nutrients. You may be thinking only of the visible fruiting bodies / crops, but most mushrooms are invisible, underground, and a high percentage (perhaps more than any other kingdom) is symbiotic with species from other kingdoms.

  4. Thank you for your comment, Yonah. Fungi and other decomposers are indeed important in maintaining ecosystems, as I pointed out in paragraph 10 (the third one from the end) of this article. The idea of mushrooms as symbols of insouciant selfishness is not a biological one to be taken literally, but simply a metaphor used in the Kabbalah.

    Best wishes and many thanks for your interest in Torah Flora,

    Jon Greenberg

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