Yeah makes sense though. And for those reading Persian lime is the regular lime found in US grocery stores. Kaffir lime (one of the cornerstone species not included on the ternary axes) is the lime used in Thai food
I recently learned about the fact that Sichuan peppercorns are actually related to citrus, so was looking for where the connection is... As it turns out[1], there is a "citrus family" (Rutaceae[2]) and a citrus genus (Citrus[3], in that family). The Sichuan plant is a member of the family, but not the genus (that would be Zanthoxylum[4]). Confusing!
During lockdown I started growing clementine from seed. One of the interesting details of this genus is polyembryonism: multiple seedlings emerging from one seed. Apparently, one of the seedlings will be a clone of the motherplant and the rest will be the product of pollination/genetic reshuffling. My clementine seeds all had 2 seedlings per seed but other attempts (with lemon I think) yielded 3 or more).
During my reading I came across a lot of contradictory info about the origin of the clementine: some papers say it’s an unknown hybrid, other clearly state it’s a mutation instead of a hybrid. So it’s interesting to read the hybrid parentage in this triangle, stated with confidence.
Polyembryony is the reverse of what you think: one embryo is a result of pollination and all the others are clones. The sexual reproduction embryo is often less vigorous and sometimes doesn't develop at all. It makes it easy to reproduce "true" plants, but also makes it difficult to produce hybrids for some species.
Chinotto (apparently called mirtle leaves bitter orange in English?) also has some confused origin (perhaps it's a mutation of some other bitter orange, but it's unclear), and afaict it's not in this chart, or I can't find it.
There are lots of citruses missing; the ones in the chart are only the ones I could find reliable values for (from the sources at the bottom). I'll add more if I can find other reliable sources. For what it's worth, I think the etrog is basically a pure citron variety.
Yeah, that's definitely an issue. If I get a chance, I'll curate images to add!
I assume the esrog is the primeval citron but I've noticed that Jewish tradition (which rejects the use of hybrid citrons) allows some surprisingly different citrons in practice, popularly associated with Israel, Morocco, Yemen, Corfu etc. These differ considerably in eg rind thickness.
According to wikipedia they are cultivated from a hybrid of mandarin orange and Ichang papeda, the latter being from another wild lineage than the three shown.
You might need several more dimensions (assuming this quoted claim is correct - it does come with a Citation Needed)
> Recent genetic analysis shows the papedas to be distributed among distinct branches of the Citrus phylogenetic tree, and hence Swingle's proposed subgenus is polyphyletic and not a valid taxonomic grouping, but the term persists as a common name.
they discuss that, they were not hybridized to the same extent. They do discuss the key lime ancestry as orthogonal, it would be cool to use a tetrahedron instead to show that.
