As we know, before eating a fruit that grew from a tree one recites the Beracha of "Borei Peri Ha'etz," whereas before eating a vegetable, that grew from the ground, one recites "Borei Peri Ha'adama."
This gives rise to the question of how we define a "tree" for purposes of this Halacha. According to Rashi (Rav Shlomo Yitzchaki, France, 1040-1104), a "tree" is a plant that retains its branches and stalk all year long. If the stalk and branches remain even after the fruits have been removed, and the following year the fruits will grow again from these same branches, then the plant qualifies as a "tree," and one would recite "Borei Peri Ha'etz" when partaking of its fruits. Rabbenu Chananel likewise brings this view in the name of the Geonim.
The Rosh (Rav Asher Ben Yechiel, Germany-Spain, 1250-1327), however, gives a different definition of "tree" with respect to Berachot. In his view, a plant can be considered a tree even if it loses its branches and stalk each year, provided that the roots remain, such that the stalk will grow anew the following year. Only a plant that has to be planted again each year constitutes a "vegetable" and requires the Beracha of "Borei Peri Ha'adama." If the roots remain intact and automatically produce a new plant the following year, then we consider this plant a "tree" and its fruits would warrant the recitation of "Borei Peri Ha'etz."
One common fruit whose Beracha is affected by this debate is the banana. The banana tree does not remain standing all year round, but its roots do remain and produce a new tree each year. The Shulchan Aruch rules that over a banana one recites "Borei Peri Ha'adama." This ruling follows Rashi's position, that a plant that does not remain intact all year round is not considered a "tree" with respect to Berachot, even if its roots stay in place.
An interesting question arises concerning the eggplant. The stalk of the eggplant remains in place even after the eggplants are removed, but in order to produce more and higher quality fruits, farmers generally cut the stalk and leave it on the ground. A new stalk eventually grows from the old plant and produces new eggplants. Does this plant qualify as a "tree" for purposes of the recitation of "Borei Peri Ha'etz"?
The consensus among the Poskim (halachic authorities) is that since, when all is said and done, eggplants grow each year from a different stalk, it would not, according to Rashi's definition of "tree," be considered a tree with respect to Berachot. And since, as mentioned, Halacha accepts Rashi's definition, when eating eggplant one recites the Beracha of "Borei Peri Ha'adama."
Summary: Halacha defines a "tree" as a plant whose stalk and branches remain intact all year long, even after its fruit is removed. Therefore, over bananas and eggplants one recites the Beracha of "Borei Peri Ha'adama."
