In message , Stewart Robert Hinsley
writes
I came across this whitebeam sapling yesterday, but on second thoughts
I'm not sure what it is. Any ideas?

http://florulaurbana.blogspot.com/20...m-is-this.html

Thanks everyone for your suggestions.

My newsfeed was down most of today, but in the interim I've added some
more observations and photographs to the blog. Same URL.

http://florulaurbana.blogspot.com/20...m-is-this.html

There are 4 Sorbus found in the UK which have free basal leaflets -
Sorbus x thuringiaca (******* service tree = aucuparia x aria), Sorbus x
liljeforsii (aucuparia x intermedia), Sorbus hybrida (Swedish service
tree) and Sorbus pseudofennica (Arran service tree). (Note: these plants
may be service trees, but they're still whitebeams in my idiolect.) None
of the other British endemics have, fide Stace, free basal leaflets, nor
are they known to occur in this area; the only Sorbus recorded wild from
the hectad (up to 2000) are aucuparia, aria (agg.) and latifolia. (So
confirmation that I also ran across torminalis today would be nice.)

The first three taxa have scattered records over the British Isles.
(Sorbus x thuringica is about twice as common as the other two.)

Sorbus x thuringiaca and Sorbus x liljeforsii would be expected to have
more free basal leaflets and more lateral veins that the plant I
encounted; hence my second thoughts that it was Sorbus hybrida, rather
than my original misidentification on cursory examination as Sorbus
intermedia. The number of basal leaflets is low even for Sorbus hybrida,
so I was concerned about the possibility of some other taxon irregularly
producing leaves with free basal leaflets, perhaps especially when
young. As today I encountered additional plants with (0)-1-2 basal
leaflets my concerns are somewhat alleviated.
--
Stewart Robert Hinsley