Where is the Royal Botanical Garden located?

$A$ student of taxonomy was puzzled when told by his professor to look for a key to identify a plant. He went to his friend to clarify what 'Key' the professor was referring to? What would the friend explain to him?

Which of the following statements are correct?
$I.$ Plants collected during field studies are pressed and dried on herbarium sheets.
$II.$ The label on the right-hand side of the herbarium sheet contains the scientific name,family,and common name of the plant.
$III.$ Botanical gardens contain collections of plant specimens as well as illustrations,slides,maps,and photographs.
$IV.$ Living plants can be observed and identified in botanical gardens.

Statement $P$: $A$ herbarium is a storehouse of plant specimens collected from various places.
Statement $Q$: There are specific methods for preserving plant specimens in herbaria.

Which of the following can provide taxonomical relationships?

Where are maps and botanical books collected and stored?