User:Mapl/Taxonomy

On tagging a plant's taxonomy

Before reading my take on this, I strongly recommend User:Olr/Tagging_von_Bäumen, a very beautiful writeup on this issue. However I try to be self-contained, e.g., because that article is only available on German (although, any online translator may solve this issue.)

The only point where I am currently of different opinion then Olr is that I would always include genus=*. While he proposes to specify a small-leaved lime by

• species=Tilia cordata
• taxon:cultivar=Greenspire

I would further add genus=Tilia just like tagging leaf_type=broadleaved and leaf_cycle=deciduous for every fruit tree, although this can be inferred from any of the taxon ranks. I believe the increased eases for automatic processing outweighs the extra effort.

It goes without saying that what I am proposing is only what I consider the best practice.

Preferred tagging of taxon:wikidata=*

Currently (as of 2025-05-23), the wiki page Key:taxon:wikidata is in a dire state, mostly a duplicate of Key:genus:wikidata, with some minor discrepancies, which makes it even worse.

However I consider it to be the most relevant tag for plants on OSM.

I am missing a discussion, when to tag species:wikidata=* vs genus:wikidata=* vs taxon:wikidata=*.

According to Tag history comparison, it seems like taxon:wikidata=* is getting more popular (still on a low level compared to the other two). According to taginfo on taxon:wikidata, the majority of 80% of elements with taxon:wikidata=* does not also tag species:wikidata=* or genus:wikidata=*.

Linking to wikidata should only be done on the lowest possible level. Inferring parent taxons Q18674606 (Malus domestica) and Q104819 (Malus) from Q504565 (Belle de Boskoop) should be done on the wikidata side. In a case where all data is available, tagging species=*, genus=*, taxon:cultivar=* / taxon=* and taxon:wikidata=* has the advantage, that only the most specific link is provided, but all parent taxons up to genus=* are directly visible in the element.

Legitimate tagging of species:wikidata=* and genus:wikidata=*.

If I only know a plant's genus, for example if I come across an apple tree, I may know that it's species is Malus domestica, or with my limited knowledge, I may even only know it's of the genus Malus. Thus these three variants are legitimate representations:

When only the genus is known.

• natural=tree
• [...]
• genus=Malus
• genus:wikidata=Q104819

When the species is known.

• natural=tree
• [...]
• genus=Malus
• species=Malus domestica
• species:wikidata=Q18674606

When the precise taxonomy is known.

• natural=tree
• [...]
• genus=Malus
• species=Malus domestica
• taxon:cultivar=Belle de Boskoop
• taxon:wikidata=Q504565

The alternative would be to always use taxon:wikidata=* for the most specific known taxon rank. However, that way, an inconsistent state, resulting from adding a more specific taxonomical description without updating the wikidata link, would be less transparent. genus:wikidata=* and species:wikidata=* are much better at communicating what their respective value expresses.

A further situation, where using species:wikidata=*, as described in Key:species:wikidata, the case where a sub-species is not relevant enought to have its own wikidata ID.

Usage of taxon=* and taxon:cultivar=*

While taxon=* should include a string with the complete taxonomic determination of a plant, taxon:cultivar=* only specifies the part which comes after the species. This results in a bit of an unbalance between mapping a Prunus domestica subsp. domestica (Zwetschge) versus mapping a Belle de Boskoop apple

taxon:cultivar=Belle de Boskoop compared to taxon=Prunus domestica subsp. domestica.

This imbalance could only be resolved by mapping Zwetschgen with taxon:subspecies=* or subspecies=*, which only has been done in six instances worldwide. Taginfo subspecies. Hence our best option is to let this imbalance remain and be fine with it.

It seems to be uncommon to map both taxon=* and taxon:cultivar=*, such as in Node 2043958056 V3. This possibly adds too much redundancy with not much benefit.

I have also found places where taxon=* simply repeats the species=* when no more specific taxonomical classification is known, such as in Node 1535792680 V1. This seems to me to be redundant as well.

Further examples from the map.

Only putting this here, so you can compare side-by-side, if you are a visual person like me: I prefer Node 9812329754 V2 (Zwetschge) to Node 7598807045 V3 (also Zwetschge) because it

• has no redundant genus:wikidata=* link and
• exhibits the most specific taxonomic determination taxon=Prunus domestica subsp. domestica.