[dr_kiszonka]

Very nice renders!

Since you are an expert, could you share whether L-systems have any practical applications?

[knutae]

Aristid Lindenmayer used it originally as a model to study the growth of algae, so it has some scientific applications. While computer graphics is the most common use case, L-systems have also been used for generating music.

http://algorithmicbotany.org/papers/ has a list of papers and other related texts, including the classic book The Algorithmic Beauty of Plants.