When my 3-year old, 5-foot tall and lovely etrog tree suffered a bug infestation last winter, I sprayed a mixture of soap and water on the leaves because I was reluctant to use carcinogenic commercial plant sprays. (I make etrog jelly each year for childless women, as etrog is known as a "segula" for childbearing.) I did too good a job, however, and all the leaves fell off from their soapy shower.
I couldn't bear to part with the naked branches of the tree I'd nurtured all these years. I kept the tree in my dining room, near the sunny wintertime windows, hoping for an agricultural miracle. This past spring, a lone green shoot sprang near the base of the sickly plant . Today, a trio of bright green leaves appeared on an upper branch that is otherwise brown and dry. The situation reminds me of techiat hamaitim, resurrection of the dead, especially since etrog symbolizes the human "heart." It also reminds me of emunah, faith, since I had hopes that the tree could revive (despite the despairing sighs of visitors). Does an etrog have other symbolism to be aware of?
According to Jewish Tradition the etrog tree is very special. There is an opinion in the Talmud that the Tree of Knowledge was the etrog tree. One of the things that makes it so special is that the bark is of the same flavor as the fruit. When G-d created the world, His original command was that the trees as well as the fruit be edible. The etrog tree is the tree that symbolizes this ideal relationship that is supposed to exist between mankind and nature. (Of course mankind has proved over and over again that we are so destructive that if trees were edible we would have uprooted them ages ago!)
The etrog fruit itself is also chock-a-block full of symbolism. According to early sources the etrog symbolizes the heart (its shape is reminiscent of the heart). The importance of the heart is that it both receives blood and pumps blood into the system. That is, it gives as much as it takes! Aside from that there is a very famous statement of the sages that each one of the four species represents a different kind of Jew. The etrog, having both a beautiful smell and taste, represents those Jews who have both good deeds and Torah knowledge. In effect the etrog symbolizes what it is that we should aspire to be!
There is a fascinating midrash which relates that the wife of Potiphar, being upset at her inability to seduce Yosef, began to look less than her normally well-groomed and beautiful self. Her friends became concerned so she invited them round to her house to show them the reason. As they were all sitting around eating etrogim, Potiphar's wife called Yosef to come into the room.
Before she had a chance to warn her friends, they had all cut their fingers with the sharp knives they were using to peel their etrogim, because they were completely transfixed by Yosef's beauty! The symbolism is impossible to miss: Yosef would not succumb to the advances of Potiphar's wife precisely because he was an etrog (if one can say such a thing)! His beauty was more than skin deep!
Hashem should bless you that your tree grow tall and strong and that you continue to be involved in kind deeds for many, many more years to come!