NOTES

משנה ד

שתי שורות - Each of the species in this משנה are separated by a תלם, or furrow, as described in the previous משנה, however the foliage of these  particular species tend to grow longer and would bridge that gap, thus, a single row of each cannot be planted next to each other.  Only by pairing rows of these species together, this overlap is muted; the רע"ב says that this is because two adjacent rows of the same species look like a field. 

רבי אליעזר מתיר וחכמים אוסרין - According to R' Eliezer, even though the two identical rows are not adjacent, they are sufficient have the entire plot of land considered to be a field of that variety, thus allowing single rows of the other varieties to be planted next to them.  The Sages say that as long as the two identical rows are not adjacent, this formation is prohibited; the implication of this explanation, given by the רע"ב and others, is that the רישא of our משנה is לאו דוקא dealing with a case where all three species are paired, but rather one adjacent pair is sufficient.

משנה ה

נוטה שער של זה לכאן - I.e. It appears that the text of the משנה ends at this point, and starting with this phrase, the remainder is repetitive, does not appear in older copies, and appears to be the erroneous inclusion of a commentator's text (מלאכת שלמה, שינויי נוסחאות).