More on Salix city

I walked around the Ocean, anticlockwise, more slowly than the other day, and keeping an eye on as many trees as possible between the path and the lake.

Crack Willows

The first thing I thought was that at the southern end of the Ocean there is a lot of the Crack Willow, Salix fragilis (L.), the majority of the trees on the skyline. Mixed in were Ash, Grey Willow, Alders, Hawthorn, Blackthorn. The upperside of the Crack Willow leaves at this time of year are mid-green and quite glossy, with a whitish grey on the underside. The tip is quite acuminate, while the serrations on the margin are quite prominent, and somewhat uneven. The petiole is generally over 1 cm long, the twigs glossy but of variable colour, or there may be several different types present.

Crack Willow is a complex species aggregate, both in the UK and on the continent. There are many clonal variants, generally unisexual, and most of them are likely to have originated in the catchments and other areas from human activity of one sort or another. The taxonomy is very difficult. The leaves do seem to be a bit more subject to Willow Anthracnose, in comparison to the White Willow, Rusty Willow and Osiers covered below.

I was puzzled not to see obvious glands, usually figured projecting in odd shapes from the junction of the petiole and lamina.

White Willow

Salix alba appears generally to have smaller, neater, leaves obviously glistening white as they billow in the breeze. Close up it may be difficult to see the tiny hairs, except on the edges in profile, in with the minute serrations. The stems are initially silkily pubescent as well, going yellowish as they age. No stipules visible in September, and I didn't see any glands on the petiole.

Osiers

To the south and southeast, and again to the north there are good individual plants and patches of the Common Osier, Salix viminalis, L. One plant had very narrow smaller leaves, and could perhaps have been var. angustissima, but Meikle states that almost any plant will degenerate into this state if sufficiently neglected.

The shoots are generally upright, on what to me seem quite rounded bushes. The short indumentum covering the underside of the leaves and the stems and next year's buds is very attractive. On the stems the indumentum extends about half way down the current year's growth, making the younger stem a lovely silky dull green, but as it wears away, leaving a glossy green epidermis on the older stem. Last year's growth has an matt olive-brown bark covering it. The upperside of the leaves is a dull green, hardly lustrous at all. The revolute margins and the undulations are quite obvious. The underside of the leaves are silky grey with the thousands of tiny apressed hairs, and lots of small veins curving strongly towards the tip, which project downwards below the lamina, so leaving a tiny dip on the upperside of the leaves, and repeating the pattern along the incredibly long laminas. The leaves are often tattered and damaged, perhaps by leaf beetles and/or leafhoppers.

There are, but quite difficult to spot, very long, lanceolate, almost linear stipules. The canaliculate (not very obvious in September) petioles have large boat-shaped bases covering a large proportion of the bluntish woolly catkin-buds laid down for the following year, giving the string of pearls effect noted in the Collins guide. The indumentum of the stem is pierced by orange-brown stomata, generally with a central split. 

Leybourne and Salix city

Its all very difficult when you want to start to get to grips with the genus Salix. At Leybourne there is plenty of scope and there may be Salix alba, Salix fragilis, Salix caprea or Salix x reichardtii, Salix cinerea, and Salix viminalis, together with a large number of variants, cultivars and hybrids. I have suddenly remembered that there is a reference collection of Salix at the Sevenoaks Wildlife Reserve!

This is a suspected Salix cinerea ssp. oleifolia, but it will need checking and re-checking! I noticed one strium on the small section of last year's wood I remembered to collect.

Comma chrysalis, Lawyers Wig and Willowherb Downy mildew at Dene Park

I really find it difficult to get satisfactory photos with the mobile - I don't know whether it is focussing or shake that is the main issue.

The Comma chrysalis was absolutely fantastic - and the photos do  not do it any justice at all. I would never have seen it if it wasn't on some sallow whips that had been largely stripped by what I think might be the Willow Sawfly - see below. The chrysalis was just under an inch long I would have said, and here there is a front view and then a side view. The photo just can't capture the wonder of the silvery patches.

I found two or three of the Sawfly larvae as well, maybe the final instar. They may be the Lesser Sawfly, Nematus pavidus, which seems to be the commonest on Goat Willow.

The Tawny Owl was heard for the third evening in a row, and it was heard twice tonight. Nice to think of this male setting up its winter territory for next spring, presumably having successfully moulted over the last couple of months. "Tawny Owls remain within their nesting territory all the year round and pair-bonds last for life. They are generally monogamous but some males are known to be polygamous. The first territorial fights occur as early as October and November, the male determining the territory, the female the nesting hole. The transition from autumn to winter is marked by a final establishment of territories and pre-breeding behaviour. The female and male tend more and more to roost together. Courtship feeding begins in the winter period (December to February), becoming progressively centred on the future nest site.  In Europe the Tawny Owl usually begins breeding in mid-March." from the website: http://www.owlpages.com/owls.php?genus=Strix&species=aluco.

The area for a territory in good woodland may be as little as 12 Hectares, and the area bounded by the track walk is 26 Hectares, so there is perhaps enough room in this central patch for perhaps two territories, and perhaps more in the wood as a whole. However I have only heard the one male, and it could be the same male as heard for the past few years, and therefore possibly the same pair, as pair-bonds are generally for life (although a few males are thought to form polygamous bonds - that must be hard work!). Any young produced over the years will presumably have dispersed to new vacant territories in the area, if any have been available!

"Tawny Owls lay from two to six eggs, but sometimes only one. The eggs are almost round and pure white and are about 46.7 x 39mm. Normally, they are laid at intervals of 48 hours, and are incubated for 28-29 days by the female alone. When the young have hatched, the male brings more food, either to the nest or to the female waiting nearby. Once the chicks are 6-7 days old the female may leave the nest only to hunt, otherwise remaining near the young. Fledging occurs after 28 to 37 days. Tawny Owls are dependent on their parents for food up to three months after leaving the nest.  As the young owls gradually learn to fend for themselves they also establish territories." (ibid.).

As well as the owls taking up territory, other signs of the developing season are the profusion of different fungi, including these Lawyers' Wigs, or Shaggy Inkcaps, Coprinus comatus, at the start of the track to Ringlet Triangle. This is the best of a bad set of photos. The season is rushing along. Already some have completely deliquesced.

This is a very edible fungus, but other species at least are NOT to be mixed with alcohol within the same week! Eat quite young and very fresh for best results!

The access trail is just wonderful

Dr. Beverley Glover from the Plant Sciences Department in Cambridge suggests that the surface of petals has multifaceted functions. There appear to be projecting cells or groups of cells - these can be extremely useful perhaps for insect feet to grip onto, or for the light to be concentrated - this may make the petals look brighter, or perhaps rather more importantly the increased radiative energy input could warm the petals up - there is certainly evidence that bumblebees prefer warmer flowers.

Warmer nectar could also be important for bees searching for food on cold mornings - they have to warm themselves up, they may not want to have warm up the nectar they are drinking as well!

Flowers appear to have had such surface projections from an early stage in evolution. Flowers that don't have them, appear to have secondarily lost them.

Of course sallows don't seem to have these issues - they do not have petals, so clearly they do not have these projections? However they certainly seem to smell delicious at close range. They also attract huge amounts of insects, in conditions that may not always be the warmest! Here is a Bombus terrestris that is enjoying the sallow catkins along the outward path of the access trail at about 6 in the evening.

The Buff-tailed Bumblebee, Bombus terrestris, was accompanied by numbers of Bombus vestalis, the Southern Cuckoo Bumblebee. Here you can see the white tail and the yellow edges at the boundary of the tail, contrasting somewhat with the true orange of the front thoracic band. This looks like mimicry of the buff tail of the Buff Tailed Bumblebee!

The yellow at the tail is not always clear - hopefully this bee is still B. vestalis!

This is a better and therefore more reassuring shot, of the same bee. You can see the yellow edge to the white tail more easily at this angle. Note also the shiny thorax, easily seen in this photo.

Here is a close-up of the antenna - 12 segments altogether, rather than 13, shows it to be a female

Also on the sallow were one or two relatively small black bees - female flower bees, Anthophora plumipes. I haven't seen these on Sallow before, but there were plenty of males by this tree, but at ground level, nectaring off the Ground Ivy, Glechoma hederacea.

However when I looked at these photos of one of the other apparently small black bees there was clearly a bit of a red-tail, so realistically that led me to either Bombus lapidarius or Bombus ruderarius. I looked as closely as I could and the hind leg on the left looks as though any hairs on the rear tibia were black, not red, so that pointed to the commoner species, Bombus lapidarius. On the right hand wing you can also just see the pale cross bar in the small cell (first submarginal cell) at the front of the wing.

Sallows and shovellers at Whetsted

It was a lovely warm afternoon and the sallows in the hedgerow between the gravel pits looked very promising. The insects seemed to be making their specific choices of the ripest or tastiest trees, and some were therefore much more popular than others, which appeared deserted.

Just beyond the first of the three big oaks, a sallow was attracting honeybees, filling their leg baskets with yellow pollen:

Moving on to other sallows in the row, as well as quite a few more Honeybees, Apis mellifera, I found three species of bumblebee, Bombus terrestris, rupestris and hypnorum. B. hypnorum, the tree honeybee is a very new species to the UK, having arrived since 2000, on the back of a significant expansion of its range in Europe. As this is a new species for me I had it checked out on ispot, and David Notton from the Natural History Museum, and Stuart Roberts from BWARS, amongst a few others, kindly confirmed the ID.

There was also a bee-fly, Bombylius major, hovering as it fed.