On plain texts and ciphers (a thought experiment)

[Wladimir D]

A constructed language doesn't have to follow natural language tendencies for grammar. As an example, mathematics is a form of constructed language that is well understood by mathematicians, so well that they can write jokes to each other in "math' that can't even be translated into regular English (programmers have these kinds of jokes too, humor that simply isn't explainable to a nonprogrammer) but it doesn't follow natural language rules of grammar and many aspects of it can't easily be expressed in words (which is why students of math have to learn the symbology in addition to listening to lectures on the concepts). In fact, different branches of math and physics have different "grammars" and a mathematician specializing in one can't necessarily read the others.

A constructed language to explain plants and cosmology (assuming the text is meaningful and in some way related to the images) probably wouldn't lean toward the math side, it would probably lean more toward the linguistic side, but it's still possible to describe things in ways that are quite different from natural language grammars (which, in themselves, can be quite variable).

 JKP / You forgot to mention the language of chemical formulas.

In addition there is an international "language" of radio telegraphist, in which a combination of symbols which denotes a concept. There is also "informal slang" for the transmission of not normative lexicon.