Cystolith is made up of

$A$ vascular bundle in which two patches of phloem are present on both sides of the xylem is called:

Cystoliths, sometimes deposited in plant cells, are crystals of (aggregation of)

Assertion $:-$ Collenchyma forms the hypodermis of dicot stem.
Reason $:-$ This is the reason for flexibility of young dicotyledonous stems.

According to Haberlandt $(1914)$,the conducting part of the phloem is known as:

Apple and potato obtain $O_2$ through