The Shulhan Aruch rules (Orah Haim 206) that if a person recited the Beracha of "Boreh Peri Ha’etz" over a food that requires the Beracha of "Boreh Peri Ha’adama," he has not fulfilled his obligation, and he must then recite "Ha’adama." Something that grows directly from the ground – such as lettuce or other vegetables – cannot be said to have grown on an Etz ("tree"), and thus even after the fact, the recitation of "Ha’etz" does not fulfill the obligation, and the correct Beracha must be recited.
In the reverse case, if one recited "Ha’adama" over a fruit which requires "Ha’etz," he has fulfilled his obligation Be’di’abad (after the fact). Since fruits grow on trees which grow from the ground, the Beracha of "Ha’adama" is appropriate for fruits, even though of course one is supposed to recite "Ha’etz" over fruits. Therefore, after the fact, one has fulfilled his obligation if he recited "Ha’adama" over a product requiring "Ha’etz."
It is unclear whether a person who recited "Ha’adama" in such a case and then immediately realized his mistake should correct himself, or just eat the fruit. Some contend that since the Beracha of "Ha’adama" suffices after the fact, there is no need for the person in this case to correct himself. Others, however, argue that the person should correct himself in order to recite the Beracha that is supposed to be recited. This question has not been definitively resolved one way or the other.
In a case where one mistakenly recited "Ha’adama" over a fruit, the Beracha covers all foods on the table that require "Ha’adama." Thus, for example, if a person recited "Ha’adama" over an apple, and there are vegetables on the table, then he does not have to recite "Ha’adama" a second time over the vegetables. Although his Beracha of "Ha’adama" was recited by mistake, nevertheless, it covers all the vegetables in front of him.
This applies also to one who mistakenly recited "She’ha’kol" over a food requiring a different Beracha. The Beracha of "She’ha’kol," after the fact, covers all foods. And so if one mistakenly recited "She’ha’kol" over a fruit, for example, his Beracha covers the fruit as well as any other foods in front of him, such as water. This is mentioned by Yalkut Yosef, citing his father, Hacham Ovadia Yosef.
Finally, the Radbaz (Rav David Ben Zimra, Egypt, 1479-1573) ruled that if one mistakenly recited "Ha’adama" over a fruit, and other people at the table listened to his Beracha with the intention of fulfilling their obligation, they fulfill their obligation even though the Beracha was recited mistakenly. This can happen on the night of Rosh Hashanah, when the head of the household customarily recites "Ha’etz" over an apple or date for everyone at the table, who fulfill their obligation by listening to his Beracha. If he mistakenly recited "Ha’adama" over the fruit, both he and they have fulfilled the obligation. This is the Radbaz’s ruling, and it was accepted by later Poskim.
Summary: One who mistakenly recited "Ha’etz" over a food requiring "Ha’adama" has not fulfilled his obligation, and must then recite "Ha’adama." However, if a person mistakenly recited "Ha’adama" over a food requiring "Ha’etz," he has fulfilled his obligation. (If he realized his mistake immediately after reciting "Ha’adama," it is uncertain whether he should correct himself.) This recitation of "Ha’adama" covers all foods on the table requiring "Ha’adama," and if others intended to fulfill their obligation by listening to this Beracha, they, too, fulfill their requirement, even though the Beracha was not the proper Beracha.
