Goat willow and grey sallow

[treecreeper]

I live near an area of damp ground which has a large population of willows. This year I am trying to identify them all, starting with goat willow (salix caprea) and grey sallow (salix cinerea ssp. oleifolia up here ...my books tell me you East Anglians have your own subspecies, you exclusive people!).

I am keeping samples of twigs and catkins in compartmentalised boxes (pictured). When mature leaves are available I will add samples of these to the collection.



I have numerous botanical books to help me, the most important of which are probably New Flora of the British Isles by Clive Stace (1997) and Willows and Poplars of Great Britain and Northern Ireland by R.D. Meikle (1984)

I have separated goat willow from grey sallow by peeling back the bark on the two year old twigs. If it is smooth I have assumed it is goat willow. If it bears longitudinal ridges I have assumed it is grey sallow. But this is rather destructive and I am looking for a better way of separating these species in spring before the leaves are out.

I have been looking at the bracts below the catkins (I don't mean the tiny black-tipped catkin scales which Stace also calls 'bracts'). In all the willows I have looked at there seems to be a difference. Goat willows, both male and (slightly less markedly) female, have rather elongated bracts with only slight reddish coloration. I have called these gorse-bracts because they remind me of the sepals of gorse flowers. Pictures:





Grey sallow, on the other hand, has more compact and rounded bracts with more red coloration. I have called these ladybird-bracts. pictures:





Does anyone have comments on catkin bracts as a diagnostic? It is not mentioned in any of my books.

I have also been looking at the colour of the male catkins. Goat willow catkins invariably have bright yellow stamens but grey sallow stamens are frequently red-tinged. Not every catkin has this red colour, but every grey sallow I examined had at least some reddish catkins, and sometimes the colour was very noticeable:



Interestingly, this feature is mentioned in all my older books but hardly ever in my more recent titles, and not at all in Stace or Meikle.

Any comments on catkin colour?

I'll just add that I have looked at willows further afield (the other end of Meols!) and the distinctions in bract shape/colour and stamen colour seem to hold.

[Hedge Witch]

Hi treecreeper, very interesting thread. Thanks for this. I will be more observant in the field now. And I'll be following others comments with interest.

[Lance Morgan]

Willows are well known for cross pollination and there are many hybrids.

[treecreeper]

Originally Posted by Lance Morgan

Willows are well known for cross pollination and there are many hybrids.

According to the books there an unbroken series of hybrids between goat willow and grey sallow, i.e. backcrossing in both directions. I might get a better idea of this when the leaves come out. I'm not sure how common these hybrids are relative to the pure species. I'm hoping a salicologist will log on to the forum and enlighten me!

[Lance Morgan]

Good Luck TC

[Tiggrx]

Originally Posted by treecreeper

According to the books there an unbroken series of hybrids between goat willow and grey sallow, i.e. backcrossing in both directions. I might get a better idea of this when the leaves come out. I'm not sure how common these hybrids are relative to the pure species. I'm hoping a salicologist will log on to the forum and enlighten me!

The hybrid between Goat & Grey Willows (Salix x reichardtii) is generally quite common and apparently is commoner than Goat Willow in many areas

[treecreeper]

Originally Posted by Tiggrx

The hybrid between Goat & Grey Willows (Salix x reichardtii) is generally quite common and apparently is commoner than Goat Willow in many areas

It's just occurred to me it might not be known in detail which areas these are ...in which case I might be doing some real science!

[Hedge Witch]

Originally Posted by treecreeper

I'm hoping a salicologist will log on to the forum and enlighten me!

Oooh, a salicologist, that sounds interesting

[treecreeper]

Originally Posted by Hedge Witch

Oooh, a salicologist, that sounds interesting

In R.D. Meikle's book (Willows and Poplars of Great Britain and Ireland) he often gives taxanomic history, quoting people he calls 'salicologists' back to the early nineteenth century. So there were specialists then as well as botanical vicars.

RDM has sneaked a bit of humour into what is otherwise a very dry and serious book. In the introduction, under 'Collecting Willows', he writes 'Catkins should be fully developed, but not overripe, and male catkins should be kept apart from females, and separately numbered, not for moral reasons, but because they must normally have come from separate individuals, and may not "belong" together'.

[Hedge Witch]

LOL That appeals to my botanical sense of humour