Mishnah Uktzin 2:1: Regarding olives which one pickled together with their leaves, they [i.e. the leaves] are pure [and are not considered to serve as handles or to preserve the fruit], for they were pickled only for the sake of appearance. The fibers on a zucchini and its flower are pure. Rabbi Yehudah says: so long as it is before the merchant [selling it], it is impure.

זֵיתִים שֶׁכְּבָשָׁן בְּטַרְפֵיהֶן, טְהוֹרִים, לְפִי שֶׁלֹּא כְבָשָׁן אֶלָּא לְמַרְאֶה. כְּשׁוּת שֶׁל קִשּׁוּת וְהַנֵּץ שֶׁלָּהּ, טְהוֹרָה. רַבִּי יְהוּדָה אוֹמֵר, כָּל זְמַן שֶׁהִיא לִפְנֵי הַתַּגָּר, טְמֵאָה:

Mishnah Uktzin 2:2: All pits can be rendered impure, and render impurity, and do not join together [with foods to count towards the measure for impurity]. The pit of a damp [i.e. fresh] date, even when detached, does join together [with the date to count towards the measure for impurity]; that of a dried [date] does not join together. Therefore, the surrounding membrane [of the pit] of a dried [date] does join together, but that of a fresh one does not join together. Regarding a pit which is partially detached, the part opposite the edible portion does join together. A bone which has meat on it, the part that is opposite to the edible part joins together [with the meat to count towards the measure for impurity, since it serves to preserve the meat]. If it had [meat] on one side, Rabbi Yishmael says: we view it as though it [i.e. the edible part] encircles it like a ring [and thus that entire part of the bone does join together]; and the Sages say: the part opposite the edible part joins together, as with savory, hyssop and thyme [where only those parts which are opposite the edible parts join together to count towards the measure for impurity].

כָּל הַגַּלְעִינִין מִטַּמְּאוֹת וּמְטַמְּאוֹת וְלֹא מִצְטָרְפוֹת. גַּלְעִינָה שֶׁל רֹטֶב, אַף עַל פִּי יוֹצְאָה, מִצְטָרֶפֶת. שֶׁל יְבֵשָׁה, אֵינָהּ מִצְטָרֶפֶת. לְפִיכָךְ, חוֹתָל שֶׁל יְבֵשָׁה, מִצְטָרֵף. וְשֶׁל רֹטֶב, אֵינוֹ מִצְטָרֵף. גַּלְעִינָה שֶׁמִּקְצָתָהּ יוֹצְאָה, שֶׁכְּנֶגֶד הָאֹכֶל, מִצְטָרֵף. עֶצֶם שֶׁיֵּשׁ עָלָיו בָּשָׂר, שֶׁכְּנֶגֶד הָאֹכֶל, מִצְטָרֵף. הָיָה עָלָיו מִצַּד אֶחָד, רַבִּי יִשְׁמָעֵאל אוֹמֵר, רוֹאִין אוֹתוֹ כְּאִלּוּ הוּא מַקִּיפוֹ בְטַבַּעַת. וַחֲכָמִים אוֹמְרִים, שֶׁכְּנֶגֶד הָאֹכֶל, מִצְטָרֵף, כְּגוֹן הַסִּיאָה וְהָאֵזוֹב וְהַקּוֹרָנִית: