What is meant by L in a scientific or botanical name?

Answer 1

Botanical/ scientific names are sometimes followed by an abbreviated form of the person who first described the species (as a suffix).

In your instance L. or sometimes Linn. refers to Carl Linnaeus, the actual "author" of the taxonomic system called binomial nomenclature; this is the system that is in use today to describe each and every species of plant, animal, fungus, bacteria and virus on the planet.

Carl Linnaeus amongst other things was a fervent botanist and described literally hundreds of plant species (using his system) - hence the inclusion of his abbreviated name following the genus and species name.

Answer 2

Carolus Linnaeus also known as Carl von Linné, who also developed the binomial

nomenclature or the Latin name for naming organisms.