NOTES

משנה ח

סדן של שקמה - This variety of sycamore is actually a species of fig tree native to the Middle East and eastern Africa (ficus sycomorus).  The רע"ב says that even though it is a fruit tree, it grows in forests, was not cultivated and was primarily used for lumber (פרק ו, משנה ד).  The משנה ראשונה says that even though it bears fruit, the fruit are inconsequential ("אינו חשוב הפרות שלו דמדבריות הן") and, although it is therefore considered a tree that does not bear fruit, nonetheless it is אסור  to graft vegetables into it.  Furthermore, the משנה ראשונה points out, the חדוש of this משנה is that even though, in all of these grafts, the intent is not to combine the different species to produce a new hybrid, but rather to have one nurture the other in some way, nonetheless this constitutes sufficient intent for the graft to be אסור. 

פיגם - Many translate this as rue, but there are several varieties of rue, most of which grow as shrubs or trees, which would not be consistent with the context here of ירק באילן.  Common rue, however, was grown as an herb, which is more consistent with this context.

קידה לבנה - This tree is often identified as cassia or Chinese cinnamon, a species of the cinnamomum genus, whose bark is usually sold and labeled in the United States as "cinnamon" (although it is not "true" cinnamon, a related species in the same genus native to Sri Lanka).

החצוב - It is not known what exactly this plant is, though it is the subject of discussion in (:ביצה (כו and (.בבא בתרא (נו; from there it is at least apparent that it had roots that penetrated deep into the ground without spreading laterally, and was used by Yehoshua to mark the boundaries within Eretz Yisroel.  Jastrow speculates that it is cistus, a perennial flowering shrub, whileכלאי זראים והרכבה identifies it as squill, a bulb-forming perennial herb.

שיהא מקרו - Both the רמב"ם and the רע"ב say that this means that the fig scion will temper, or cool (לשון קור), the stronger or hotter flavor of the חצוב; a second פשט given by the רע"ב is that the scion cools the rootstock with its shade, like a beam or a rafter (לשון קורה) would.  The (מלכת שלמה (בשם הח' הרב יהוסף אשכנזי raises two problems with these interpretations:  First, it is doubtful that a valuable fig branch would be used in the service of a plant used solely for fodder, as was apparently the case with חצוב.  Second, these פשטים are not consistent with the arrangement of the other pairs in this משנה (at least according to the מלכת שלמה), as in every other case it is the first species that is benefitting from the second.  As such, he concludes that the fig shoot here is benefitting from the חצוב by being planted in this shrub, as it has a more secure and protected location for it to put down roots.  (There is a גירסא of the ירושלמי that reads "שיהא מקורו" (i.e. "so it should be its source") which is consistent with this position.)

זמורה של גפן - Note that there are several other conditions governing planting grapevines near other plants to avoid the prohibition of כלאי הכרם that are the subject of later פרקים, according to the ירושלמי this משנה is dealing with an instance where all of those conditions have been met, and focuses only on the separate prohibition against grafting.

שתהא זורקת מימיה לתוכה - The תוי"ט brings the ר"ש, who, citing the ירושלמי, indicates that it was the root of the vine that was placed in the watermelon, not just a detached branch.

הטומן - According to the רע"ב, by placing bundles of turnips and bundles of radishes together, it is evident that they were placed under the ground without the intent to grow them there, but merely to store and preserve them, thus avoiding and prohibition of כלאים.  The מלכת שלמה disagrees and states that even burying individual bundles of either turnips or radishes is sufficient to show the intent was for storage.

אם היו מקצת עלין מגולין - Some are of the opinion that this requirement is only for the plants' removal on Shabbos; either because this way one can take them out by pulling them by their leaves and not directly disturb the soil with one's hands ([:רע"ב, רמב"ם, רש"י [שבת, נ), or because the protruding leaves prevent the removal of the plant from giving the impression that a new hole had been dug ([.ריטב"א [שבת, נא).    However, according to ר' האי גאון the משנה reads "אם היו מקצתן מגולין", as according to him part of the bulb of the turnip or radish needed to be exposed.  He apparently held that our משנה is addressing individual turnips or radishes placed under the soil, and if only their leaves are left above ground, it is as if it was planted, not merely placed there for storage.  Therefore, he held that the requirement was for part of the bulb of the plant to remain exposed, and not just to avoid problems on Shabbos, but necessary to avoid the other restrictions mentioned by the משנה as well.

ולא משום שביעית - This applies to the אסור דאורייתא of planting during שמיטה, but even if the stored vegetables were to grow while underground the אסור דרבנן on consuming produce that had grown during that year would not apply either.

רבי יהודה אומר, אינו כלאיים - According to the רע"ב, R' Yehuda holds that the פסוק of "שדך לא תזרע כלאים" implies that two different seeds are being planted (as implied by the plural "כלאים") in soil that already has something planted there (which is implied by the word "שדך" as opposed to bare ground which would probably be denoted with the word קרקע or ארץ).    Thus, in a patch of barren ground, three seeds would need to be planted, one to make it שדך and another two to be the כלאים in that field.