Botanist makes connections between Judaism and plants

Jon Greenberg, a “biblical and Talmudic botanist,” leads a guided tour of the Montreal Botanical Garden.

Who knew there was an “etrog problem” that perplexed strictly observant Jews for more than a century after a scientific discovery cast doubt on their millennia-old belief about the citrus?

Jon Greenberg – an Orthodox Jew with a PhD in agronomy, whose license plate proclaims, appropriately, that he is from the “Garden State” – does. Clad in his trademark Indiana Jones-style fedora, this “biblical and talmudic botanist” is eager to share his expertise, which bridges the divide between ancient religion and modern knowledge.

Greenberg earned his doctorate at Cornell University and also studied at Yeshivat Hamivtar in Israel.

A science teacher at a Jewish high school in New York by day, Greenberg is the creator of Torah Flora, a program through which he leads Judaic-themed tours of public gardens and talks at synagogues and schools around the United States about plants, agriculture, nature and food, as they relate to Judaism.

Greenberg gave his first tour of the Montreal Botanical Garden in July. His knowledge of the vast landscape came from what he found online, but he felt completely at home once he got there.

Almost every plant he encountered prompted another story about its connection to Judaism. A tangelo tree in the greenhouse got Greenberg started on etrogim, which are used in the celebration of the harvest festival of Sukkot.

He explained that the tradition has its origin in Leviticus 23:40, which says that, on the holiday, Jews should bundle together four species, including “the fruit of a beautiful tree.” The word “etrog” does not appear in the text.

“What is this fruit? The debate in the Talmud deals only with the question of how it can be proven that the fruit in question is the etrog (Hebrew for ‘citron’). The discussion there assumes that it is an etrog; there is no minority opinion that it is something else,” he said.

“Commenting on this passage of the Talmud, Maimonides says that this is an example of a more general pattern: when the oral tradition recorded in the Talmud is unanimous about how a biblical commandment, such as the four species, is to be carried out, this means that this has always been the practice of the Jewish people.”


All this was fine until the advent of the scientific study of the domestication of plants and animals began in the late 1800s.

“No one was able to find archeological evidence of the presence of the etrog in the Middle East before the fourth century BCE (unlike the other three ‘species’), and it was thought to have been confined to East Asia at that time. This conflicted with the Jewish tradition, creating the etrog problem,” said Greenberg.

“The first break in this standoff between Torah and science was the discovery of 4,000-year-old etrog seeds in northern Iraq in the early 1990s. The second was the discovery of late First Temple period – sixth century BCE – etrog pollen embedded in the plaster of the villa at Ramat Rachel in modern Jerusalem, near the city’s ancient site. Because it is not native to the area, this showed that this species was cultivated there during biblical times.”

That discovery spawned a deeper debate, Greenberg continued, namely, whether any of this matters to Jewish religious practice.

“Should we care about this archeo-botanical validation of our tradition, or can we just continue to rely on the Talmud and Maimonides, and let the scientists find their evidence when they can, even if the difficulty of finding it sometimes leads to these apparent conflicts that may later be resolved with further research?” he asked.

The banana posed a dilemma for observant Jews, as well, Greenberg noted, as he stood before the tropical plant. Despite appearances, it is not a tree. The “trunk” is not made of wood; it’s made of leaves rolled tightly together. Therefore, the bracha should be that for “a food of the earth,” like vegetables or herbs, he explained.

At times, it seemed a though Greenberg had a story about just about every plant in the garden. The cinnamon plant nearby was one of the spices used as incense in the Temple, he explained. The papyrus brings to mind the basket woven from the grass in which the infant Moses was born.

The “seven species,” of which the fig was one, were important because they all produced pollen in the period between Passover and Shavuot in the Land of Israel, thereby promoting monotheism. Why? Because the Israelites were less likely to “hedge their bets” and presume that there were separate deities for each crop if they all flowered at the same time, he said.

Greenberg was not so cheerful when he came across an “anti-Semitic” plant: the common Wandering Jew. The purplish vine got its name in the Middle Ages because “it spreads like Jews taking over a town,” he said.

Modern-day Israelis may like to call themselves “sabras,” but cacti are not native to the Middle East, said Greenberg as he passed a prickly specimen.

Greenberg hopes to return to the Montreal Botanical Garden next summer to lead a larger group. He hopes to spread his enthusiasm for showing that Judaism and flora are not strange bedfellows. Indeed, the Torah provides ample evidence of how interdependent they are.


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