Back with the mosses

Invariably, at this time of the year, my attention turns to those fascinating organisms, mosses. There must be a name for this interest. Bryomania? Hardly in my case; I have never felt the urge to dash off to a remote Hebridean island in search of some bryological gem. Of course, I rarely find anything other than very mundane species but this is no surprise, given that the habitats I investigate are almost equally mundane. But it doesn't stop me from searching, and  I'm always prepared to be surprised. In fact Northamptonshire really does have a poor moss flora. As our county moss recorder, Rachel Carter, recently wrote regarding the results of a meeting: ' The dearth of interesting bryophytes in Northamptonshire reflects the genuine poverty of the [moss] flora'. The county has obviously no coastline, very few exposed rocks, ditto marshes and no acid bogs. 'Bland' is the word that springs to mind.


Walls are always worth checking out and it is only when a wall has been recently repaired with new stone that we realise what a softening effect mosses have; the new section may look neat but the appearance will, to me, always be raw und slightly jarring.


Of course it is wall mosses that are the first to come to the notice of most people. They generally form little green cushions and mosses of this type are known as acrocarpous. The other form of moss, often the bane of gardeners, has a pleurocarpous habit and is typified by the straggling mosses such as Springy Turf-moss, Rhytidiadelphus squarrosus, which colonise lawns, particularly where the soil is poorly drained.  From above the leaves appear to have a star-shaped pattern.

Springy Turf-moss at Windmill Hill, Newnham, Northants.

6 November, 2016

No matter which group a moss belongs to, a careful examination with a lens shown them to be organisms of great delicacy and beauty.  Truth be told, for me the study of mosses represents a steep learning curve, starting with almost zero knowledge. And I constantly get side-tracked, as when I bent down yesterday at the foot of Windmill Hill to look at a lichen-encrusted tree trunk and almost brushed my nose against these wasps.

About a dozen of them had congregated on some oak leaves. What was special about these leaves was unclear. The insects were in a torpid state and were probably moribund. Chances are they'd be dead by nightfall.

A little further on and I came upon a dead branch bearing a troop of tiny fungi. They were cup-shaped with each fruiting body no more than 5mm across. Undoubtedly they were some sort of Resupinatus. Almost certainly the species was R. applicatus, known as the Smoked Oysterling, but as with mosses, they're a bit outside my field.

Smoked Oysterling on a dead twig beside the A45, Daventry.

6 Novembert, 2016

With progress as slow as this I looked around and realised that dusk was setting in and a dew was forming on my clothes. Stupid boy! 

Surprise on a dismal day

Earlier today I trudged around Dennett's Garden Centre in Daventry. In the chilly, grey, sunless conditions I found little to catch my interest. Only yesterday, in brilliant sunshine, I had been photographing a Red Admiral butterfly in my front garden as it imbibed nectar at a Hebe. (Of course we must now refer to Hebe species as shrubby Veronicas - but that is another story.) Where was I?


Red Admiral on Veronica (Hebe). Stefen Hill, Daventry.

31 October, 2016

Back to the garden centre. I stooped to read a label and there on the gravelly path at my feet glistened a wrinkled patch of greenish jelly. Perhaps a 'jelly lichen', I thought, but which one? Putting down a 50 pence coin for scale I took a photograph.

When enlarged the details became clearer. Perhaps a Collema species?

These curious organisms are not my 'thing' but following a careful examination I concluded that it was Collema auriforme. The specific name means 'ear-shaped' and certainly some of the folded lobes of the thallus are rather ear-shaped. It is reasonably common in England and it is not unusual to find it on mortar, but I was inordinately pleased. The day suddenly seemed brighter.

Oaks

Oaks, i.e. Quercus species, belong to the Fagaceae, a family which includes beeches and the Sweet Chestnut. Just over 6oo species of Quercus are known, with a large proportion being found in North America; there are two species native to Britain, Quercus robur and Q. petraea, and two others, the Turkey Oak and the Holm Oak, are widely naturalised. In all cases the fruit consists of an acorn (Old English ac, an oak, and corn, a seed).
Here in the south midlands, and over the south of Britain generally, the commonest Quercus is the Pedunculate Oak, Quercus robur.  The word 'pedunculate' refers to the long slender stalk  - peduncle - upon which the acorns grow. It is found on deeper, often wettish, neutral to alkaline soils, and is found across Europe to the Caucasus and beyond.

Pedunculate Oak. The acorn is situated on a slender stalk. Kentle

Wood, Daventry. 29 October, 2016

The Sessile Oak, Quercus petraea, is commoner in the north and west of Britain. It is a tree of thinner, stony (the word 'petraea' is derived from the Greek petra, a rock) more acidic soils and will often be found quite high up in the hills. In Northamptonshire it is relatively uncommon but there are some acid grasslands in the west of the county and a visit to Newnham windmill produced a result.  Windmill Hill is capped with acid soil - bracken, tormentil and gorse are present - and there stood a Sessile Oak.

The distinctive leaves of Sessile Oak. Windwill Hill, Newnham,

Northants. 31 October, 2016

I was unable to find acorns but the leaf shape is characteristic. with the leaf-blade tapering down to the petiole. By contrast, in the case of the Pedunculate Oak the base of the leaf has a pair of lobes, often referred to as auricles.


Pedunculate oak showing (top of picture) the lobes at the

 leaf base. Daventry, 1 November, 2016

For centuries only one Quercus species was recognised in Britain but with care the differences are easy to see. The leaf of Pedunculate Oak shown below is covered my what I at first thought was sooty mould. I am now convinced that it shows the poo of Harlequin Ladybirds, of which there have been enormous numbers this summer.


Another view of a pedunculate oak leaf showing the lobes

 more clearly. Daventry, 1 November, 2016

It will surprise no one to find that the hybrid Quercus robur x Q. petraea (Q. x rosacea) can be quite frequent where their ranges overlap.
The Turkey Oak, Quercus cerris, can be instantly recognised when in fruit by the long scales on the cup.

Turkey Oak in the grounds of Danetre Hospital, Daventry.

26 October, 2016

These scales turn outward and the cup encloses roughly three quarters of the acorn.

The same tree, showing the acorn...

When not in fruit the leaves are quite distinctive, being relatively slender with up to ten rather pointed lobes on each side.




...and the leaves.

The Holm Oak, Quercus ilex, is sometimes simply referred to as the Ilex. (Our native holly is Ilex aquifolium and the pretty little Kermes Oak, Quercus coccifera, widespread around the Mediterranean, has rather spiny, holly-like leaves.) The Holm Oak is evergreen and not obviously an oak at all, until its acorns are noticed.

The glossy, evergreen leaves of the Holm Oak are

distinctive. Byfield Pocket Park, 29 October, 2016

A small grove of Holm Oak exists at the southern end of Byfield's pocket park and, after a good deal of searching, a couple of the rather small acorns were found.

The acorns of the Holm Oak are rather small. Byfield Pocket Park,

29 October, 2016



The tree is quite resistant to salty winds and has often been planted near to the sea. Many woodlands around Sheringham in Norfolk consist largely of Holm Oak and on the Isle of Wight it has become a pest, and a large-scale eradication program is now being undertaken. Incidentally, many of the leaves of the pocket park specimens displayed the mines of the common Garden Midget Moth, Phyllonorycter messaniella. It probably does little harm.

Holm Oak leaves showing the mines of the Garden Midget, a common

moth larva on oaks. Byfield Pocket Park, 29 October, 2016

Other exotic oaks may be found in collections from time to time - but I must not allow myself to go beyond the remit I have set myself.

A carpet of leaves

On my way to Kentle Wood I pass trees in their autumn glory. The Narrow-leaved Ash, Fraxinus angustifolia, has been widely planted hereabouts and one reason  must be the wonderful autumn coloration of its foliage. It is quite variable - perhaps the nature of the soil is a factor - and ranges from a lovely salmon-pink colour...

Fraxinus angustifolia beside the A45 in Daventry. 27 Octeober, 2016

 ... to a rich maroon purple.

Fraxinus angustifolia again, a little further along the road.

The woodlands of Maine, in the north-east of the U.S.A. are justly famous for their colours in the fall and huge numbers of visitors visit the region to marvel at the sight. Much of the coloration is due to the presence of Acer species - maples and sycamores to you and me - but here in Britain Acers can also take on lovely autumn colours, the intensity of which seems to depend on the weather over the previous two or three months and again, possibly, the soil. Is it my imagination or do trees growing in acid soils develop a brighter red autumn foliage?
The most familiar Acer to most people is the Sycamore, Acer pseudoplatanus. It is probably an introduction but as the pollen is virtually indistinguishable from that of Field Maple there is room for doubt.


Sycamore, Acer pseudoplatanus, beside London Road, Daventry.

26 October, 2016

For some reason the autumn colours of Sycamore are, I find, particularly vivid on saplings.

The autumn foliage of a sycamore sapling. Byfield, Northants.

2 November, 2016

The Field Maple, Acer campestre, is undoubtedly native. It is a generally smaller tree than the sycamore and its leaves often assume a primrose-yellow hue in autumn.

Young (c. 20 years old) specimens of Field Maple, Acer campestre.

Kentle Wood, Daventry. 27 October, 2016

And of course the land beneath the trees in Kentle Wood is becoming carpeted in leaves.

As a child I loved shuffling through this multi-coloured layer, kicking up golds, russets and crimsons in whispering showers. I was not alone in this joy and the present generation of children are equally enthusiastic. My boyhood friend Trevor Hold was also familiar with this joy:

                                           
                                           "See me somersault," he cries

                                            diving onto the mattress of dead leaves,

                                            and seeking a womb, he burrows like a mole

                                            among the brittle death-shapes

                                            of oak and sycamore,

                                            then pokes out a face

                                            laughing in resurrection.

                                                        'Boy among leaves' from 'Mermaids and Nightingales'

                                                                          by the late Trevor Hold, 1991

 Gradually, as the weeks pass, a task force moves in to work on the breaking-down of this seasonal bounty. There are the larger, obvious invertebrates such as woodlice, millipedes, slugs and snails, but anyone sifting through this material will quickly become aware of the generally smaller springtails. These vitally important creatures are a bit of a taxonomic puzzle: they are obviously arthropods, but just where do they fit in?   Should we regard them as an odd group within the insects? That would be convenient but not very satisfactory. As we delve into the leaves they leap around like tiny seashore shrimps - and this is what causes difficulties. Springtails possess an organ called the furca and the unique nature of this mechanism, allowing them to leap for surprisingly long distances, is the problem. How and when did it evolve?


I am embarrassed to admit that, although I have the necessary key to the springtails, I never seem to find the equally necessary time to identify them.

Important though these creatures are, pride of place must go to the minute fungi and bacteria that ultimately return this organic treasure to the soil to form humus. The vital role of these organisms cannot be overstated and we ignore them at our peril. (A recent report by the United Nations Food and Agricultural Organisation predicts that the earth may only have 60 years left for growing crops given the present rate of soil destruction and loss, so soil renewal by processes such as leaf fall are vital.)


Personally, if I investigate dead leaves I am in search of a different group of creatures, the spiders. In the depths of winter, when all seems lifeless, the number of spiders going about their business can be astonishing. Some are active hunters, ever on the move, pausing at intervals to allow the hairs on their legs to detect the slightest movement. These hairs, generally only visible under a microscope, are called trichobothria; they are incredibly sensitive but, from the point of view of an arachnologist, also important in the job of identifying the species in question, particularly with regard to 'money spiders'. Other spiders employ a different strategy, building a simple web and playing the waiting game; for both these groups springtails must form an important prey item.
The carpet formed by autumn leaves is a vital but, as far as I am concerned,  under-investigated habitat. I must use the next few weeks to start and remedy this situation.


* Sycamore is generally regarded as an introduction but not all botanists are convinced. For some the jury is still out.

Ladybirds

Odds are that the first beetle recognised or observed by a child will be a ladybird. At one time it would probably have been a Two-spot Ladybird, Adalia 2-punctata, or a 7-spot Ladybird Coccinella 7-punctata. Unfortunately today it is as likely to be a specimen of the aggressive Harlequin Ladybird, Harmonia axyridis - aggressive in that this recent arrival to our shores is partial to the larvae of other ladybirds (but also its own species).

In most areas the commonest ladybird is still the 7-spot, which has three spots on each wing-case (elytron, plural elytra) and one on the suture, i.e. the dividing line.  The spots are not present when the adult first leaves its pupa but develop within the first few hours.

Seven-spot Ladybird in my garden at Stefen Hill, Daventry.

12 June, 2016, above its black pupal case.

I photographed this specimen of the 7-spot in my back garden as it left the black pupal case; the elytra slowly took on a red coloration and the spots gradually appeared like a photograph being developed. This species in particular is aphidophagous but other species eat aphids too. In his book on ladybirds ('Ladybirds', Richmond Publishing, 1989) the late Michael Majerus divides the apparently defenceless aphids into kickers, walkers and droppers. The first group kick out at an attacking ladybird, the second group attempt to move away - apparently quite a successful strategy - and the droppers simply fall to the ground.
Anyway, I digress.

Calvia 14-guttata at Sixfields, Northampton. 2 June, 2016

Ladybirds come in a range of colours and this brown species, Calvia 14-guttata, was on a shrub near Sainsbury's at Sixfields, Northampton. It is quite frequent and is known as the Cream-spot Ladybird.

When I said that 'other species eat aphids', I implied that some had an alternative food source. Several species are herbivorous, and feed on mildew. The familiar yellow and black 16-spot Ladybird, Micraspis 16-punctata, is one such species, while the tiny 24-spot Ladybird, Subcoccinella 24-punctata, feeds on clovers and vetches.
Of course, the larvae of ladybirds are also distasteful and bear warning marks to deter birds and other would-be predators. The picture shows the almost fully-grown larva of a Harlequin Ladybird, Harmonia axyridis.


Larva of a Harlequin Ladybird, Daventry town centre,

24 May, 2016

Once the larva emerges from the egg it must find food quickly. The larva of the Two-spot Ladybird, Adalia 2-punctata, will only survive for about a day, perhaps a day and a half, before dying. It will survive on meagre rations but be smaller than a well-fed specimen.
I suppose around three quarters of the ladybirds I encounter are Harlequins and the remainder are largely Seven-spots, but occasionally others make an appearance. The Eyed Ladybird, Anatis ocellata, is nationally quite common but is largely confined to pine trees and their relatives.

Eyed Ladybird, Anatis ocellata, on a fence in Byfield, Northasnts.

25 October, 2016

When one turned up in Byfield I was quite surprised as I have not recorded it there before and pines in the area are few and far between. It is one of our largest ladybirds and each black spot is edged with a cream-yellow border, making it quite distinctive. I must be more observant.

Spines and cyanide

I recently posted a blog bearing the title of  'Autumn Leaves', in which I considered the phenomenon of leaf fall. 'But what of plants such as holly?' I hear you cry.


Its evergreen nature has made this tree very important in ritual over the millennia, for whereas the winter appears to bring about the death of deciduous trees, to be followed by a rebirth in spring, holly appears immortal. Of course holly does lose its leaves, but at a fairly constant rate throughout the year and anyone attempting to crawl under a holly tree becomes quickly aware of this when hands and knees receive sharp prickly reminders, especially as the dead leaves are slow to rot.


By bearing its tough, waxy leaves throughout the winter holly is able to take advantage of early spring sunshine but the downside is that its leaves are available to hungry animals which can, and do, browse the trees. Interestingly, studies in south-eastern Spain, reported in the Botanical Journal of the Linnean Society, have shown that when holly is browsed there is a rapid response at molecular level, with far spinier leaves being produced. This tendency for leaves on higher branches to be free of spines has been known for centuries and a vague memory led me to a poem by Robert Southey. In it he wrote:


                          No grazing cattle, through their prickly round,
                          Can reach to wound;
                          But, as they grow where nothing is to fear,
                          Smooth and unarmed the pointless leaves appear.


                                                                   The Holly Tree, Robert Southey 1774-1843


Be that as it may, even the smooth leaves are tough and unpalatable to many animals and are avoided where better browsing is available.  Even insects tend to eschew (rather than chew!) the leaves but one exception is the fly, Phytomyza ilicis. Here its very familiar mine is photographed on a spine-free holly leaf, but they are just as happy on a spiny leaf as, for this insect, the spines are irrelevant. (The caterpillars of the Holly Blue butterfly, Celastrina argiolus, normally restrict their diet to the flowers and buds.)


Phytomyza ilicis on a holly leaf in the churchyard at Norton,

Northants. 22 October, 2016

Another tough-leaved evergreen is Cherry Laurel, Prunus laurocerasus. This is a very popular garden shrub but, unlike holly (no relative), it is not native to Britain.




Cherry Laurel is familiar in gardens, often being used for

hedging. Daventry, 21 October, 2016

Whether in gardens or in semi-wild shrubberies it is rarely nibbled by deer, rabbits and so on and yet its leaves are unarmed. The defence is more subtle yet equally effective: the leaves are laced with cyanide. To be more precise, cyanogenic glucosides in the form of prunasin and amygdalin are present. (I know: I'm not an organic chemist either.) These substances are also present in the cherry-like berries, with nasty consequences for children who might be tempted to sample them. If I am out and about looking for leaf-mining insects I give Cherry Laurel only the briefest of glances although the presence of a tiny moth, the Apple Leaf Miner (Lyonetia clerkella) is sometimes confirmed, its larvae producing characteristic sinuous mines pale against the dark leaf.


Cherry Laurel is a member of the rose family, Rosaceae, as is the Almond, Prunus dulcis. The smell of cyanide is often likened to almonds and the kernel of the almond nuts does contain cyanide. This is no more than a harmless trace in the edible varieties but the nuts of ornamental almonds are to be avoided as there the levels of cyanide compounds make them distinctly toxic.

Not to be eaten! Ornamental almond at Newnham, Northants.

22 October, 2016

Back to evergreen shrubs, and I must mention Ivy, Hedera helix. To what extent will stock eat it? What defences does it have? According to the old song:


                             Mares eat oats and does eat oats and little lambs eat ivy...


...and up to a point this is true. According to my book - admittedly rather old (it was produced by the Ministry of Agriculture, Fisheries and Food) - 'Poisoning in animals can be ... serious, as large quantities of leaves and berries are sometimes eaten'. It appears that substances called saponins are present in all parts of the plant, although this doesn't stop the ripe berries being an important late-winter food for birds such as thrushes. It seems that at one time farmers would give cattle a few ivy leaves as a 'tonic' and this practice seems to have been harmless. Incidentally ivy belongs to the Araliaceae, a family largely of tropical lianas, and is completely unrelated to the Poison Ivies of North America. These latter plants belongs to the Cashew Nut family, the Anacardiaceae.


So we should not be surprised to find that otherwise palatable plants use a variety of defences to ward off hungry animals. Across the plant kingdom a huge range of dodges are employed, some quite bizarre - but  that is another topic.
Postscript
A day after publishing this blog I noticed a holly lookalike in a nearby garden and I couldn't resist giving it a mention. It is, of course, the variegated form of Osmanthus heterophyllus.

Despite spiny, evergreen leaves it is not in the Holly family, Aquifoliaceae, but is a member of the Olive family, Oleaceae.

Autumn leaves

The autumn winds have begun their job of stripping leaves from the trees. Among the first to go seem to be those of ash; a few briefly clung to my car windscreen a couple of weeks ago before being whisked away. In ten weeks or so the trees will be revealed, Ishtar-like, in their naked state.



The shedding of leaves is of course, amongst other things, an excretory mechanism. A number of abscissional cells develop to form a weak point at the petiole base, allowing the leaf to fall without damaging the tree. As the leaf falls it leaves a scar and in the case of the Horse Chestnut it is very distinctive. The scar resembles a horseshoe, complete with nails, and it is widely believed that this feature has given the tree its common name. For clarity (?) I have shown the scar upside down.


Horse Chestnut twig. Stefen Leys Pocket Park, Daventry.

10 October, 2016

As the leaves fall they take with them various substances such as tannins which would otherwise be harmful. These unwanted substances can include toxic metals and much interest is being shown in using trees not only to remove these metals from contaminated soils, but as a way of 'harvesting' these potentially valuable materials.


Oak leaves turning gold. Aston le Walls Pocket Park.

9 October, 2016

So the leaf, in falling, takes with it unwanted and harmful chemicals. But there is another very good, obvious, yet often overlooked reason why a tree will shed its leaves. As summer advances the leaves will begin to experience many kinds of attack from other organisms to a point where a leaf is rendered almost useless.


One source of trouble can be galls. The photograph shows a dozen or so galls of Neuroterus quercusbaccarum, the Common Spangle Gall. These are overwhelmingly on the under side of an oak leaf and a group like this will probably not have much effect.


Oak leaf with Spangle Galls. Aston le Walls Pocket Park.

9 October, 2016

However, the upper side of the leaf is also affected, and a severe attack will render the leaf unable to photosynthesise.

The upper side of the galled leaf.

Some problems can be referred to mildews. The leaves of this sycamore, Acer pseudoplatanus, photographed recently in Byfield, have been attacked by Uncinula aceris, making the leaf look as though it has been splashed with white paint. Again, they will now perform very inefficiently.




Acer sapling beside Byfield Village Hall. 12 October, 2016

Also affecting sycamore is the fungus known as Tar Spot, Rhytisma acerinum. It has been known from Europe since 1794 and, according to the literature, can affect a number of Acer species. However I have only found it on sycamore; Field Maple, Acer campestre, seems largely unaffected even when the two species are growing side by side. Cleaner air was thought to be allowing the disease to become more prevalent but there is little evidence to back this up.



Tar Spot on sycamore, Badby Road West, Daventry.
14 October, 2016

Caterpillar damage is also an obvious problem. In my own garden my Rose 'Canary Bird' has had some of the leaves skeletonised by the larvae of the Rose Slug Sawfly, Endelomyia aethiops.




Damage caused by the Rose Slug Sawfly, Stefen Hill,

Daventry. 19 October, 2016

These now-useless leaves can be shed during the autumn but the caterpillars will have formed a cocoon in the soil beneath the rose; they will return next spring to wreak further havoc unless I take appropriate measures. Incidentally males of this species are extremely rare and so reproduction is almost invariably by parthenogenesis. As a rule the depredations of caterpillars are of little consequence but severe infestations by, for example, box tree caterpillars, can eventually lead to the death of the affected plant.


There is no doubt that the autumn leaf fall is a phenomenon worthy of our attention and not just Nature's way of providing us with beautiful photographs.