Who is known as the father of botany?

$A$ system of classification in which a large number of traits are considered is

Which study is essential for the identification and study of diverse organisms in the biosphere?

The best definition of a species is:

The common name of pea is simpler than its botanical (scientific) name $Pisum$ $sativum$. Why then is the simpler common name not used instead of the complex scientific/botanical name in biology?

$Nicotiana$ $sylvestris$ flowers only during long days,while $N.$ $tobacum$ flowers only during short days. If raised in the laboratory under different photoperiods,they can be induced to flower at the same time and can be cross-fertilized to produce self-fertile offspring.
What is the best reason for considering $N.$ $sylvestris$ and $N.$ $tobacum$ to be separate species?