Sukkah 11a and Sukkah 11b, kinds of bed coverings within a sukkah that do not invalidate it, what to do with items still growing out of the ground that we want to use as sechach, whether cutting it away from the ground after it already is on top of the Sukkah is enough of an action to make it sechach, and why sechach has to grow from the ground and not be susceptible to ritual impurity.
