One wonders here if the direct object for the phrasal verb bring forth is missing. We expect “bringeth forth fruit”, as in other places in the allegory of the seed:
Elsewhere in the text there are 98 occurrences of “to bring forth” in the active (there are also four cases of the passive, all excluded from this discussion). For 97 cases, the direct object for the verb bring forth is explicitly stated. The single exception is found in a biblical quote where the direct object relative pronoun is lacking but implied: “and none to guide her among all the sons she hath brought forth” (2 Nephi 8:18). Interestingly, this exception is a King James biblical quote that cites Isaiah 51:18, which actually has the direct object relative pronoun (namely, whom) but in italics (which means that the relative pronoun is not in the Hebrew). In any event, there is no other passage like the one here in Alma 32:31 with its unexpressed direct object. 𝓞 is extant for this passage and reads without the direct object, so if fruit was lost from the text, it would have occurred as Joseph Smith dictated the text to Oliver Cowdery. One possibility is that the visual similarity of forth and fruit could have led Joseph to accidentally skip over the word fruit as he read off the text to Oliver.
Of course, there is really nothing wrong with Alma 32:31 since it is understood that every seed brings forth in its likeness. And in the King James Bible, there are 20 instances where the verb bring forth lacks an explicit direct object; and two of these deal with the fruit of plants:
The reading “for every seed bringeth forth unto its own likeness” in Alma 32:31 is perfectly acceptable, although unique for the Book of Mormon.
Summary: Accept in Alma 32:31 the reading in 𝓞, which lacks a direct object for the verb bring forth: “for every seed bringeth forth unto its own likeness”; unique for the Book of Mormon text, this usage can be found in the King James Bible (and more generally in English).