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Posted on July 2, 2008 by Ash
It has been almost four weeks since the treeblog Set A seedlings were lined up and photographed like recently arrested criminals. In my absence the most recent mugshots were taken last Saturday (Set A Day 458) by my father. But before we get down to business, let’s talk Set B for a moment. The last post revealed a horrific deception: what I thought to be a couple of sweet chestnuts are actually nettles. This means that the only tree seedling produced by Set B is a solitary downy birch. And I’m afraid things aren’t going too well in the downy birch department. I haven’t seen the seedling with my own eyes since the beginning of June, but in the photo from Saturday (Set B Day 106)… it isn’t looking too hot. I don’t think it’s dead, mind, but it’s not exactly radiating health. I’ll let you, dear reader, form your own opinion.
The downy birch is in the centre (see the inset for an enlarged and brightened view). The other two seedlings are weeds.
Not good, is it? Ne’ermind. I’d rather not dwell on the failure that was Set B. Instead, I like to console myself with the dandy Set A:
The Alpha Scots pine. The stem is still bendy but the kebab skewer has done wonders. See the lower needles, from about half-way down? They are juvenile needles. The upper needles are adult – notice how they are arranged in pairs.
The Gamma Scots pine. My father reports that recent heavy winds had bent the soft seedling over (just as previously happened with Alpha), so he had to intervene with a kebab skewer. Again, notice the two different types of needle, adult and juvenile.
Grey alder No. 1. This alder, along with Nos. 2 and 3, has enjoyed a growth boost since being transplanted to a larger pot at the beginning of June. I’m not happy about the lean that’s developing though. A kebab skewer is going to be headed your way, sir.
Grey alder No. 2: the smallest of the alders.
Grey alder No. 3. Transplantation has done this seedling a world of good!
Grey alder No. 4: the Beast. What can I say that I haven’t said a thousand times before? It’s just one rampant seedling. Proper rampant.
…And that’s enough Set A for one post. We still have to cover the cider gums though. All fifteen will be paraded soon in Part II of this super treeblog seedling update. So 'til next time, ta-ta.
Posted on July 7, 2008 by Ash
The latest super treeblog seedling update continues... All fifteen cider gums from Set A are out on parade today. Some have seen exceptional growth since the last update at the beginning of June (Day 432); others have grown very little, and should be met with frowns. The photos were taken a little over a week ago now, on Saturday the 28th of June (with the exception of a couple taken four days later on July the 2nd). Take it away Number 1:
Cider gum No. 1. Only small, but it is one of the few that have grown branches already.
Cider gums Nos. 5 (left), 4 (centre) and 2 (right). Not particularly big, but all three have a bit of a lean on. Perhaps some kebab skewer intervention will be required soonish. No sign of any branching in this trio yet.
Cider gums Nos. 3 (left), 6 (centre) and 15 (right) – the trio pitoyable (all at the same scale). No. 3, affectionately known as ‘the Freak’, is looking less freakish these days but is as underdeveloped as ever. No. 3 was the first of the gums to show branching.
Cider gum No. 7 – the tallest of the gums! Much taller than its supportive skewer. I guess that situation ought to be amended before the top falls over or something. But while being the tallest of the gums, it hasn’t begun to develop any lateral branches yet.
Cider gums Nos. 8 (left) and 9 (right). No. 8 is another gum that has overgrown its crutch!
Cider gum No. 10. Keepin’ it average.
Cider gum No. 11. A little on the small side.
Cider gums Nos. 14 (left) and 12 (right) – the third and fourth tallest gums respectively. No. 14 is one half of the Big Branching Duo, the other half being No. 13 (below).
Cider gum No. 13. Check out all that branchy goodness. And to top it all off, No. 13 is the second tallest gum.
Posted on July 11, 2008 by Ash
Posted on July 16, 2008 by Ash
Many Sorbus species, including the common and well-known rowan [a.k.a. mountain ash] (Sorbus aucuparia) and the less common and less well-known common whitebeam (Sorbus aria), have a habit of forming hybrids (I have a friend that calls trees that readily hybridise like this, such as the European and Japanese larches, ‘sexy trees’). This has led to a bewildering range of species and microspecies throughout the British Isles, often very rare and/or unique to particular locales. Perhaps the best well-known examples of this phenomenon are the ‘Arran whitebeams’. According to the Forestry Commission:
The Isle of Arran is home to two species of tree which do not occur anywhere else in the world, the Arran whitebeam (Sorbus arranensis) and the Arran cut-leaved whitebeam [a.k.a. bastard mountain ash] (Sorbus pseudofennica).
The fun on Arran doesn’t stop there. A third speicies, the Catacol whitebeam (Sorbus pseudomeinichii), is believed to be the rarest tree in the UK with only two specimens found growing wild on Arran.
[...] “It has long been recognised that one of the botanical highlights of Arran are the endemic whitebeam trees. These are unique trees which are native to Arran and not found anywhere else in the world. But the recent investigations into the genetics of the trees with the University of Bristol have shown that the population is much more diverse than previously thought.
SNH goes on to report that deer fences are being erected to encourage seedlings to grow into mature trees. At present specimens are restricted to cliff faces where they are safe from grazers. Furthermore:
It was previously thought that the Arran whitebeam was a simple hybrid between the rock whitebeam [(Sorbus rupicola)] and the native rowan, and that the cut-leaved Arran whitebeam was a back-cross between the Arran whitebeam and rowan.
According to this article from the Scotsman [15 June 2007] a Catacol whitebeam sapling has been raised by the Royal Botanic Garden Edinburgh, so that the species can be propagated and preserved.
Posted on July 22, 2008 by Ash
It’s been a while since you last got a good look at the treeblog trees, so why not take the time to welcome them back into your life with this one-parter Set A super treeblog update? (Photos kindly taken by my father on Sunday the 20th – Day 480).
First up, the grey alders. All four show fine growth, with Nos. 1, 2 and 3 doing quite well at playing catch-up with the monstrous No. 4. Alas, No. 4 isn’t the perfect picture of health I’ve become accustomed to; notice a few shrivelled leaves amongst its ample canopy. I suppose this may have something to do with how small the pot is in comparison to the tree, so I’ve asked my father for a re-potting favour. I guess they could all do with bigger pots, but that’ll have to wait a couple of weeks for my return.
The Scots pines; Alpha on the left and Gamma on the right. Both of these bendy-stemmers are supported by crutches, as are all the tall cider gums. I think that’s quite shameful, but at least the alders can stand up on their own.
Cider gums Nos. 1, 3, 4, 6, 11 and 15: the Small and the Runts. No. 1 is looking quite good these days, and its one of the proper branchers. No. 4 and No. 11, with its flopped-over top, look like they have produced their first lateral branches. Nos. 3, 6 and 15 are as runtish as ever, sadly.
Cider gums Nos. 2, 5, 8, 9 and 10: the Tall. Aren’t these all pleasingly uniform? Nos. 2, 9 and 8 all appear to have put out their first branches, but I don’t think Nos. 5 and 10 are ready to play the branching game just yet.
Cider gums Nos. 7, 12, 13 and 14: the Very Tall. All have now well exceeded their crutches, so that is a problem that needs remedying. See how Nos. 7, 14 and especially 12 have a pronounced lean in the main stem once it is no longer tethered to a crutch. The strangest thing about this photo is the fact that No. 13, the Branch Master, is a totally different shade of green to the other three. I wonder why? No. 14, the other half of the Branching Duo is almost exactly the same height as its partner in crime, which is nice. The Top Gum (heightwise) - No. 7 - has a branch, but No. 12 hasn’t.
And there ends this super treeblog update - the next one should be online in about a fortnight. Until then, you can look forward to a post about a visit to a very rare tree. So long!
Posted on July 26, 2008 by Ash
Rock whitebeam leaves; upper surface (left) and silvery lower surface (right).
Rock whitebeam (Sorbus rupicola) is a small tree endemic to north-west Europe. According to ukwildflowers.com, rock whitebeam is
Absent from the south east of England and central and Southern Ireland, the few trees which exist are scarce and slightly more frequent the further north you go.
Not so long ago I stumbled across this .pdf document which provides details of rock whitebeam and its distribution in Edinburgh’s Holyrood Park. The document, marked “Edinburgh Biodiversity Partnership”, is over eight years old now so I will take the liberty of plagiarising big chunks of its content:
Rock whitebeam is found on steep rocky slopes or cliffs of basic rock at low to moderate altitude. It often grows in inaccessible situations... Mature individuals readily produce flowers and fruit, the latter probably being distributed by birds in order to regenerate the species in new locations.
Regarding Holyrood Park’s population, the document has this to say:
[Rock whitebeam] has probably never been common in Edinburgh, with numbers particularly declining since the turn of the century. Rock Whitebeam has been known from Holyrood Park since 1813…
Fire damage, both accidental and as a management tool, has probably had the single largest impact on the Edinburgh population of rock whitebeam. Rabbits are keen to eat the bark of the closely related rowan, and so it is likely that rock whitebeam has also been targeted. This may be the main reason for its occurence [sic] only in inaccessible places.
Although fire is no longer used as a management tool in Holyrood Park there is always the possibility of accidental fires being started. Indeed, the prevelance [sic] of fire may increase as gorse, which is highly flammable, is likely to extend its range as a consequence of the recent removal of grazing cattle and sheep from the Park and the fact that it is no longer collected for winter fodder.
Hearing that there were rare trees within a short distance of our flat, last Monday (July 21) I went on a mission with my flatmate and fellow ecologist to Dunsapie Crag to see a rock whitebeam up close. We were in luck: there were three of them at the Crag. There was a big one high up the rocky Crag face, which I presume to be the aforementioned ‘mother tree’; a smaller one beneath the ‘mother’ but still on the face; and a smaller one still growing in the grass beneath the Crag.
The ‘mother tree’.
The youngest rock whitebeam with Dunsapie Loch in the background. The leaves in the photos at the beginning of this post belong to this tree.
All three Dunsapie Crag rock whitebeams.
We didn’t go and have a look for the rock whitebeams that the “Edinburgh Biodiversity Partnership” said were on the face of Raven’s Crag, but on the way back around the west side of Arthur’s Seat we spied a couple of young specimens just below the path.
Two more Holyrood Park rock whitebeams - new discoveries?
And coming in a future post… more whitebeam wonders at Edinburgh’s Botanic Gardens.
Posted on July 29, 2008 by Ash
Well, I was down at Edinburgh's Royal Botanic Gardens on Sunday (third time that week) and it was a glorious day. I had myself a good time walking around in the sun admiring trees and taking several hundred photographs. My favourite bit of the Gardens is the Highlands area just on the left when you come in at the East Gate. Not because it is particularly well laid out, or that there are any especially interesting specimens in there, but because it is planted with the things that I am most familiar with and fond of: Scots pines, silver and downy birches, gorse, heather, bilberries (blaeberries), rowans, brooms, alders, foxgloves… These kinds of flora are familiar to me from trips to the Highlands, but mainly from living on the edge of the Peak District, where all of the above are abundant.
Only a few hundred trees of each species exist, clinging perilously to the steep rocky slopes of two remote glens at the north of the island.
This is the smaller of the two S. arranensis trees. As you can see, it is only a young 'un.
And these are some of the leaves of the small S. arranensis.
This is the larger S. arranensis. A poor photo, but it gives an idea of the form.
Leaves from the top...
...and some from the bottom.
The S. pseudofennica, squeezed in between a rowan and a birch.
S. pseudofennica leaves...
...and the silvery undersides of even more leaves.
I found a paper by Robertson, Newton and Ennos (my dissertation supervisor and one of my old lecturers) - Multiple hybrid origins, genetic diversity and population genetic structure of two endemic Sorbus taxa on the Isle of Arran, Scotland (Molecular Ecology (2004) 13, 123–134) – that clears up the origins of both of these Arran whitebeams. From the abstract:
In this study, we use an array of genetic markers in a population analysis to elucidate the hybrid origins of the Arran whitebeams Sorbus arranensis and S. pseudofennica, two woody plant taxa endemic to the Isle of Arran, Scotland. It has been proposed that S. arranensis was derived by hybridization between S. aucuparia [rowan] and S. rupicola [rock or cliff whitebeam], and that subsequent hybridization between S. arranensis and S. aucuparia gave rise to S. pseudofennica. Analyses of species-specific isozyme, nuclear intron and chloroplast DNA markers confirm the proposed origin of S. arranensis, and indicate that S. aucuparia was the female parent in the hybridization. Analysis of microsatellite markers suggests that there have been at least three origins of S. arranensis on Arran. Microsatellite markers also support the proposed hypothesis for the origin of S. pseudofennica, and indicate at least five hybrid origins of this taxon.
And from the Introduction, an explanation of the origins of S. rupicola, the subject of the last treeblog post:
...S. rupicola... (rock whitebeam), itself an autotetraploid derivative of S. aria [common whitebeam]. It is most likely that S. aucuparia was the female parent involved in this cross because S. rupicola produces seed apomictically, but has significant pollen fertility of 20%.
Being the kind and generous human being that I am, I have attempted to sum up all of that information in the following simplified graphic:
Now, I think I'll end the post here. I have more material for a future post about whitebeams in Holyrood Park (again), but I think regular readers must be sick of Sorbi by now so I'll lay off 'em for awhile!
When I was photographing the S. pseudofennica this fly accosted my hand. So I took a photograph and was pleased to see what a big fly looks like from so close.
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