#DailyBloggingChallenge (25/25)
One of the niche topics in #OpenStreetMap is depicting the genus of a tree. The current #botany hardship is to learn the differences between mountain ash (aka rowan) and European ash (aka ash).
One would think they are both from the same genus Fraxinus, since they both have the word "ash" in their name, but actually rowan is from the genus Sorbus.
The next step is to learn how to depict these two species and it comes down to how the leaf stem is connected to the branch, one is compound (ash), whereas the other is staggered (rowan). To add to the trickiness, the leaf of both species consists of compound leaflets. These leaflets are arranged along the leaf stem to create the leaf and each leaflet has its own leaflet stem.
(Of course there are many other differences like leaflet shape and count or bark shape, though trying create a method that can withstand dim lit scenarios like night.)
To imagine the differences between compound and staggered, imagine wearing a shirt that uses buttons vs one that uses a zipper. The buttons need to be aligned with their holes to comfortably wear the shirt, so they are compound. Whereas if you have a zipper, the teeth are alternating, so they are staggered.
In summary:
- rowan (genus: Sorbus) has staggered leaves,
- ash (genus: Fraxinus) has compound leaves, and
- both have compound leaflets
Fun fact: The Fraxinus genus is the predominant genus that has compound leaves.
#gardening #tree #herbalism #foraging #wildcrafting #fieldguide #flora
@cohanf then of course. Sadly this season the rowan dried up, nonetheless there is quite an easy distinction among the leaves. Rowan leaves are like saw blades whereas ash is smooth. The distinction in the bark is first noticeable in mature trees, ash bark has a diamond shape pattern to it.
@barefootstache Of course if your timing is right to catch Sorbus in flower or fruit, it's super easy! I don't personally know anything about Fraxinus, is the bark, size or shape of trunk much different?