The Source is not a hoard of forms but a rule — a few lines that, applied and reapplied, unfold into endless structure. The output is vast; its source is tiny. What looks like an ocean of detail is the shadow of a short program, run.
A real L-system: an axiom plus one rewrite rule, expanded DEPTH times, then drawn by turtle graphics. The source (axiom + rule + depth) is a handful of characters and stays fixed; the output string grows exponentially with depth. The compression ratio output/source is computed live — the sprawling figure genuinely IS the short rule, run: its whole description length is the source, not the pixels.
'The source code of reality' is the figure. What is literal is Lindenmayer-system expansion — a formal grammar whose output has low Kolmogorov-style description (it equals its generator). Real structures aren't guaranteed to be so compressible; this is a chosen family that is.