(a) The Mishnah lists garlic of Ba'al B'chi, onions of Rachpa (see Tos. R. Akiva Eiger), beans of Kilki and Egyptian lentils. Besides the name of a place, 'Shum 'Ba'al B'chi' mean might also mean - sharp garlic that cause a person to 'cry'.
(b) What is unusual about ...
1. ... the Kilki'an bean is - that it has a squarish shape.
2. ... the Egyptian lentil is - that one end comes to a point.
(c) The Tana rules that all of the above species - are Patur from Ma'asros, and may be purchased in the Shemitah even from someone who is suspected of transgressing the laws of Shemitah ...
(d) ... because they all grow wild and are considered Hefker (which is Patur from Ma'asros, and are not subject to all the laws of Shemitah).
(a) Rebbi Meir adds to the list, Karkas (a species of cabbage), and Rebbi Yossi, Kotnim (a species of lentils), but the Halachah is - like the S'tam Mishnah (i.e. the Tana Kama).
(b) The Tana also exempts the seeds of Loof ha'Elyon (but S'tam Loof has the Din of a regular vegetable), cress, onions, turnips and radishes from Ma'asros, and permits purchasing them from anyone in the Shemitah- year. 'Loof' is - a species of onion.
(c) Another name for 'Loof ha'Elyon' is - 'Loof ha'Shoteh'.
(d) The Rambam translates 'Zera Loof ha'Elyon' - as 'the upper seeds of the Loof'.
(a) All of these belong to a category of seeds, which is entirely Patur from Ma'asros - because they are not normally eaten (see Tiferes Yisrael).
(b) We would otherwise have thought that they are Chayav - because the original plants were certainly subject to Ma'asros, and we have a principle 'Gidulei Terumah, Terumah' (see Tos. Yom-Tov and Tiferes Yisrael).
****Hadran Alach 'ha'Oker', u'Selika Lah Maseches Ma'asros ****
On to Ma'aser Sheni