Shevi'is, Chapter Seven, Mishnah 5. This mishnah lists additional items that are considered food, and are therefore subject to the laws of shevi'is.
"Lulvei zeradim v'hecharuvin":
"Lulvei zeradim" - the young shoots of a tree called zeradim, identified by the translators as the tree known as the service tree.
"V'hecharuvin" - the young shoots of the carob (also called the boxer tree).
Regarding these items the mishnah says: "Yesh lahem shevi'is v'lidmeihen shevi'is" - the sanctity of shevi'is applies to the shoots themselves, and also to money received in exchange for them. And likewise "Yesh lahem bi'ur v'lidmeihen bi'ur" - the laws of bi'ur apply to them and to their money.
"Lulvei ha'elah v'habutnah v'ha'atadin":
"Lulvei ha'elah" - the young shoots of the elah, which appears throughout Tanach, and which some translate as the tree known as the terebinth.
"V'habutnah" - pistachios.
"V'ha'atadin" - thorn bushes, and certainly there were particular bushes that were fit for eating.
Of these too the mishnah says "Yesh lahem shevi'is v'lidmeihen shevi'is" - the laws of shemittah apply to the young shoots while they are still fit for eating, and the sanctity of shevi'is applies to money received in exchange for them as well.
But the mishnah then teaches something new: "Ein lahem bi'ur v'lo lidmeihen bi'ur" - the shoots of the elah, the butnah and the atadin are not subject to the law of bi'ur, and neither is money exchanged for them. The reason: they remain attached to the ground and do not disappear, and therefore the laws of bi'ur do not apply to them.
"Aval le'alin yesh bi'ur":
The leaves of these types of plants are subject to the law of bi'ur, "mipnei shenoshrin me'avihen" - the leaves do fall off from their source, from the branches, and therefore the laws of bi'ur apply to them, since they are cleared from the field - that is, they do in fact vanish and disappear from the field in the end.
In summary: in this mishnah we learned about additional items that are considered food and are subject to the laws of shevi'is: the shoots of the zeradim and the carob carry both the sanctity of shevi'is and the law of bi'ur, both they themselves and the money exchanged for them; whereas the shoots of the elah, the butnah and the atadin carry the sanctity of shevi'is, they and their money, but are not subject to bi'ur, because they remain attached to the ground and do not disappear. The leaves, by contrast, fall from the branches and are cleared from the field, and therefore the law of bi'ur does apply to them.