[the8thbit]

"Be charitable and intellectually curious. What would "open" look like?"

To really be intellectually curious we need to be open to the idea that there is not (yet) a solution to this problem. Or in the analogy you laid out, that it is simply not possible for the system to be "open source".

Note that most of the licenses listed under the "Licenses for Other Works" section say "It is incompatible with the GNU GPL. Please don't use it for software or documentation, since it is incompatible with the GNU GPL and with the GNU FDL." This is because these are not free software/open source licenses. They are licenses that the FSF endorses because they encourage openness and copyleft in non-software mediums, and play nicely with the GPL when used appropriately (i.e. not for software).

The GPL is appropriate for many works that we wouldn't conventionally view as software, but in those contexts the analogy is usually so close to the literal nature of software that it stops being an analogy. The major difference is public perception. For example, we don't generally view jpegs as software. However, jpegs, at their heart, are executable binaries with very domain specific instructions that are executed in a very much non-Turing complete context. The source code for the jpeg is the XCF or similar (if it exists) which contains a specification (code) for building the binary. The code becomes human readable once loaded into an IDE, such as GIMP, designed to display and interact with the specification. This is code that is most easily interacted with using a visual IDE, but that doesn't change the fact that it is code.

There are some scenarios where you could identify a "source code" but not a "software". For example, a cake can be open sourced by releasing the recipe. In such a context, though, there is literally source code. It's just that the code never produces a binary, and is compiled by a human and kitchen instead of a computer. There is open source hardware, where the source code is a human readable hardware specification which can be easily modified, and the hardware is compiled by a human or machine using that specification.

The scenario where someone has bred a specific plant, however, can not be open source, unless they have also deobfuscated the genome, released the genome publicly, and there is also some feasible way to convert the deobfuscated genome, or a modification of it, into a seed.