Woodruff

Under the beech trees which are so much a part of my local landscape, in April and May, woodruff reaches its best. This is a member of bedstraw family, Galium, with the specific name odoratum: the plant is rich in coumarin, which also gives scent to new-mown hay, sweet alison and the man orchid. Coumarin is toxic, with a bitter taste, and is an appetite-suppressant in mammals, which may explain why woodruff is one of the few plants to be found abundantly in the open understorey below beeches.

The living woodruff is almost scentless, the coumarin being released only as the foliage dries. The plant can remain fragrant for years and for centuries was used to sweeten the air in houses and churches; the dried leaves were placed among linen, in pillows and mattresses, between the pages of books, and even in the cases of pocket-watches.

The etymology of the second part of the name is not as obvious as I used to think. The Oxford English Dictionary says it comes from the Old English rofe or rife, “of unknown meaning”; this word can denote a wheel or something that creeps or spreads. Skeat links it to the Old High German ruofe, meaning “sweet-smelling”.

The name occurs in the poem “Springtime” (1310):

A-way is huere wynter wo, when woderove springeth

(Away is their winter woe, when woodruff springs)

It’s only by coincidence, then, that the plant, like Sir Walter Raleigh, wears a ruff. As a schoolboy I assumed otherwise. And although I studied the flowers and stem and leaves under a hand-lens, I knew almost nothing of substance about the woodruff. This state of ignorance continues today, just as I am still substantially ignorant about all living things: their evolution, genetics and biochemistry, and the subtle tactics and strategies each has adopted to defend itself from parasites and predators, to preserve, replicate and spread its DNA. That such processes culminate in something we find beautiful is just as much a mystery.

All I really know is that I am very glad to see the carpets of woodruff in spring, and when I see them I know my winter woe is away for sure.

Balsams

Small Balsam

Image: André Karwath

Much is achieved by specialization in the study of natural history, but a more open and discursive approach is often more enjoyable and can lead to some unexpected byways, and, finally, to a deeper understanding of the subject as a whole. For one feature of the living world always holds pointers to another, and another, and so on, a chain of fascination and discovery without end.

The first link in the chain is usually forged lightly enough, with an idle speculation. On a walk through Cassiobury Park, for example, an unusual, weedy-looking plant may be found at this time of year. It grows abundantly in the gloomy woodland near the canal and River Gade in the southern end of the park, especially by the paths in the vicinity of the commercial watercress-beds.

With small yellow flowers and large, toothed leaves rather like those of the Dog’s Mercury, this plant is the Small Balsam, a close relative of the Busy Lizzie which makes such an easy and attractive pot-plant. It is a native of Siberia and Turkestan, and was introduced to this country in the last century, having first been found growing wild here at Battersea in 1851.

In Hertfordshire it occurs mainly in the vicinity of certain towns, including Hemel Hempstead and Watford. Its distribution in the county can be understood when it is known that one of its favourite habitats is timber yards and that seeds were presumably imported in the 19th century as stowaways in consignments of exotic timber from the east. The presence of Small Balsam in the Gade Valley may not be unconnected with the Corner Hall Wharf at Hemel Hempstead of W. H. Lavers & Sons, the well known local timber merchants.

Having been inadvertently introduced, the Small Balsam spread out as far as it could, being checked only by its own needs for moisture and shade. Most balsams are a bit like this, never being found far from water or damp ground. The Busy Lizzie likewise needs plenty of water to keep healthy.

A second alien balsam, the Orange Balsam or Jewel-weed, is also found in Cassiobury Park, as well as elsewhere along the line of the Grand Union Canal. In fact, a map of its distribution in Hertfordshire is tantamount to a map of the course of the canal. A larger, more handsome plant, with orange flowers spotted with crimson, the Jewel-weed got here from eastern North America as a garden introduction, first turning up in the wild in Surrey in 1822. It is now locally common along most of the waterways of the Thames basin and is apparently still on the increase.

Yet a third alien balsam, the Himalyan Balsam, variously known as “Policeman’s Helmet” (from the shape of the flowers), “Jumping Jack” (from its explosive seed dispersal mechanism), or “Nuns” (for no discernible reason!) can be found in the park. A big clump grows beside the third bridge over the Gade (counting downstream), adjoining the most luxuriant growth of the Small Balsam.

Policeman’s Helmet is an even showier plant than the Jewel-weed. It can reach a height of six feet or so, has thick and often reddish stems, and large flowers in every shade of purplish-pink. Again it was introduced in the 19th century as a garden plant, a native of India and the Himalaya, and was cultivated at first as a greenhouse annual. It soon escaped from captivity and by 1855 was to be found spreading rapidly along waterways.

Now these three foreign balsams illustrate a number of the laws by which nature seems to govern her affairs. The vigour with which they have taken over our waterways shows how alien genetic stock, freed from the competition at home, can have an unfair advantage over the home-grown organisms – for it is the same with fauna as with flora. The native stock has not had time to evolve defences against them: the checks and balances built up over tens of thousands of years no longer have any meaning.

The only native balsam, the Touch-me-not, is, in plant terms, something of a failure. It puts forth its flowers in damp woods in north-west England and north Wales, being very local even where it is found. It cannot compete effectively. Man’s mistreatment of the environment is going hard with it, while its foreign cousins are actually taking advantage of man and his activities.

The four British balsams, one native and three introduced, are all closely related and are obviously descended quite recently from a common ancestor. In size, though, they show a clear differentiation. Each species occupies a slightly different niche, has a slightly different role to play: this is how new species evolve. They rarely trespass on each other’s terrain. The Small Balsam, for example, is pollinated by hoverflies, the Touch-me-not by bees, and the Policeman’s Helmet by bumblebees. As for the Jewel-weed, it may dispense with pollination altogether, its flowers often all being of a type known as “cleistogamous”.

Cleistogamy (literally, “closed marriage”) is an unusual and somewhat degenerate response to the heavy cost of producing flowers as a means of reproduction. Cleistogamous flowers are of simplified form, with few pollen grains, and automatically self-pollinate at the bud stage. Among our group of balsams there is a pretty smooth gradation in this habit, from the Policeman’s Helmet, in which it is unknown, through the Small Balsam and Touch-me-not, in which increasing numbers of cleistogamous flowers are found, to the Jewel-weed, in which cleistogamy has assumed major importance.

A study of cleistogamy in these four plants would lead us deeper and deeper into the realms of genetics and evolution. A study of their habitat preferences draws us into the fields of plant physiology, ecology, and climatology. A study of their origins takes us to the history of human trade and commerce, 19th century tastes in timber and veneer, the exploitation of Russian and Asian forests to meet those demands ...

And so it goes. Many, if not all, the scientific investigations ever undertaken have had just such trivial beginnings as a stroll through the local park and an idle question like: “What’s the name of that plant?”

(Introduction to these pieces; see all)

Lichens

Image: Ericd

The tenacity of living things sometimes surpasses belief. There is scarcely a square mile of the planet surface, no matter how forbidding, which does not support at least some form of life. The richness and diversity of living systems reach their astounding zenith in the tropical rain forests; their nadir is at the polar icecaps, especially that of the south.

Even in the polar wildernesses of rock and scree, and even, in places, in the ice itself, life may be yet found. The forms here are usually quite simple, single-celled animals and plants. Where conditions relent slightly, if only for an hour or two a day at midsummer, the terrain is colonized by lichens.

In fact, over great tracts of the world’s most inhospitable regions, lichens are the only multicellular organisms able to thrive. They grow abundantly in such daunting places as rocks which are alternately washed by the sea and baked by the sun. They will grow on walls, roofs, tree-trunks, on the bare soil. Some sorts even secrete acids which enable them to grow inside rocks, waiting for the surface to weather away before fruiting.

The key to their success is as strange as it is wonderful, and may be studied here in suburban Hertfordshire as well as in Antarctica or the Sahara desert.

Though given a single scientific name, a lichen is really a partnership of two separate sorts of organisms – a fungus and an alga. Fungi do not have chlorophyll, and so cannot use photosynthesis to manufacture their own food, as green plants (including the algae) do. On the other hand, most algae cannot, unaided, survive extreme conditions. By entering into partnership, the fungus receives sugars and vitamins from the alga, while the alga in turn gets minerals and protection from extremes of dryness and illumination; and both organisms are then enabled to colonize places previously out of bounds.

A handful of the familiar mushroom-type fungi undergo lichenization, as the process is called, but the vast majority belong to a more primitive group, the Ascomycetes.

So specialized have these lichen-fungi become that few are now able to survive for long without an algal partner. The algae, however, especially if conditions are favourable, can often exist independently. Free algae of the right sort must be available for the formation of a new lichen by sexual reproduction, for it is the fungal element alone which produces spores. The fungus is the senior partner, makes up the bulk of the lichen’s structure, and gives the lichen-plant or thallus its characteristic shape; the thallus usually has one of three main types of form: shrubby, leafy, or crust-shaped.

The clustered thalli can appear quite fantastic, like creatures from another world, or the vegetation dreamed up by an artistic imagination on the verge of madness, and the colours, which are always marvellously subtle and soft, come from Nature’s most ethereal paintbox. At different seasons and in different states of dryness the appearance may change dramatically, for during adverse conditions the lichen “shuts down” and waits for things to get better.

Unless conditions are exceptionally favourable, most reproduction is by vegetative, or non-sexual, means. Many sorts produce little powder-dusted pores which also help to keep the thallus aerated; the particles of powder are called soredia, each of which, when dispersed by the wind or by sticking to animals and birds, can grow into a new thallus. Even simpler and more common is dispersal by fragmentation: bits of the parent thallus get broken off, for example by being trampled, and blow away to develop elsewhere.

The pores in a lichen ensure that there is free flow of gases between the photosynthesizing algae and the outside world. Lichens are often efficient at absorbing whatever substances are in the environment, which has had dire consequences for those Lapps and Eskimoes who depend on caribou and reindeer for food.

One of the main components of the vegetation of the northern tundra is the Reindeer Moss, which, despite its name, is a lichen. It bulks large in the diet of the reindeer and caribou, and is the main source of carbohydrate in that particular food chain. Unfortunately, Reindeer Moss is exceptionally good at absorbing the radioactive fallout from atom-bomb tests which finds its way into the upper atmosphere and is then distributed all over the planet surface. High levels of radioactive caesium and strontium have accumulated in the bodies of the grazing animals, becoming even more concentrated in the bodies of the northern people.

So good are lichens at absorbing toxic substances that they have been used as indicators of atmospheric pollution. The lichen flora of, say, North Devon or rural Scotland is rich in species: 1400 in all have been recorded in the British Isles. But as you approach the industrial centres the number of species falls off rapidly, as does the luxuriance of growth of those that remain.

Our local lichen flora is badly impoverished, simply because the air here is so dirty. The main pollutant is sulphur dioxide, produced by the inefficient burning of fossil fuels. But others, in far smaller quantities, and even more dangerous, are contributing to the continuing decline in lichens: fluorides, heavy metals such as cadmium and lead, agricultural and garden fertilizers and pesticides, and a whole catalogue of other industrial wastes – the list is depressingly long.

Lichens may be regarded like the coal-miner’s canary. We ignore their death at our peril. The few species that remain to us in south-west Hertfordshire survive mainly by growing on alkaline surfaces, such as walls, asbestos roofs, limestone paving, and concrete, which offset to some extent the acidity of the rain.

Yet the ability of the lichens to colonize inhospitable terrain is undiminished. By poisoning the atmosphere, we have altered the balances that have remained unchanged for millennia, and those types which have become adapted to them will die. But already there are new and – almost – sinister types of lichen emerging, able to thrive in the new conditions. One, the aptly named Pollution Lichen, was unknown in Europe before 1860. A recently published guide chillingly gives its status thus: Widespread in industrial and densely populated parts of Europe. Abundant in England.

The writing, plainly printed in lichen thalli for anyone to see, is on the wall.

(Introduction to these pieces; see all)

Nettles

Image: Jerome Prohaska

Near the abandoned watercress beds, within a few yards of the stream, the ruins of an old cottage adjoin the footpath. The rubble is overgrown with stinging nettles, which protect the precincts of the cottage from intrusion.

By the middle of July the nettles have reached their greatest height. They grow here so well because the soil is rich in nitrogen – bequeathed by the middens and latrines of the former occupants. The plants are getting old and tough now, and even more uncompromising than they were in the spring. A bed of “stingers” is agony to walk through with bare legs and arms, and usually receives a punitory slashing from the countryman’s stick.

Is this punishment deserved? The nettle, after all, is only protecting its own, and uses the same irritant, formic acid, that is found in ants’ stings. Both weapons have the same purpose – to repel invaders.

The nettle’s stinging organ is simple but effective, a modified hair, long and hollow and with a swollen base into which the acid is secreted. The point of the sting is formed by a very sharp, very thin scale of silica (the basic ingredient of sand or glass). The scale is so sharp that even the slightest contact causes it to break off in the skin, making a tiny wound, and the acid is then squirted into the wound by contraction of the base, rather as in a hypodermic syringe.

If the plant is wilting, dried, or cooked, the mechanism will not work; and if you “grasp the nettle” you will not be so much stung, for many of the hairs will be bent or crushed before they have a chance to act.

The sting was probably evolved as protection from the browsing lips and tongues of deer and wild cattle, for the nettle was originally a plant of lightly shaded woodland and clearings. It is dioecious (having “two houses”), which means that the straggly catkins of male and female flowers are found on separate plants. The male flower has four stamens, each bearing a pollen-laden anther at its tip. The stamens are sharply bent inwards to the centre of the flower, being released like catapults to send their pollen dust drifting on the wind.

The flowers are rather reminiscent of those of the cannabis plant, and inside a big nettle bed, especially after a long spell of dry weather, the smell is distinctly redolent of the forbidden weed – which is not to be wondered at, because the two plants belong to closely related families.

Like cannabis, which provides the hemp fibres used still in making rope, the nettle also yields fibres which can be woven; at one time in Europe, especially in Scandinavia, nettles were widely used for this purpose. Fragments of nettle cloth have been found in a Bronze Age grave in Denmark, and cloth was produced commercially in Silesia as late as 1920. Indeed the Germans, during World War I, turned to the nettle when their cotton supply was cut off, and used it for making military clothing. Over two thousand tons of fresh plants were taken from the wild, although it needed nearly ninety pounds to make just one shirt!

Nettle makes an unexpectedly good fabric, strong and light and fine, and a nineteenth century Scottish poet, Thomas Campbell, writes of sleeping in nettle sheets and dining from a nettle tablecloth. The stalks are picked in late summer, dried, stacked, and then wetted so that they begin to rot. Next they are dried again, and beaten to remove the rotten tissue from the fibres. The fibres can then be spun into thread, like flax or cotton (though nettle fibres are not so long), and woven in the ordinary way.

The commercial growing of nettles in England in medieval times is perhaps echoed in such place-names as Nettlebed (near Henley-on-Thames) or Nettleden, near Hemel Hempstead.

Besides the cloth, nettles will make the dye, provided it is fixed with the right mordant, alum. Admittedly the colour is rather a dull green, but it was this very quality that led to our use of nettles in the Second World War. We used hundreds of tons of them for dyeing camouflage nets.

They also provided a ready source of chlorophyll. The nettle is rich besides in calcium, potassium, iron, sulphur, and vitamins A and C. The young shoots, which do not sting, can be eaten in spring as a salad or cooked like spinach and served with butter and pepper. When dried, they make a herbal tea. A year or two ago I experimented with some wild herbal teas, and although most were pretty disgusting, the nettle tea I could at least drink more than once. It had a delicate aroma and was curiously warming, like a glass of brandy. When added in small quantity to an Oriental tea, the nettle imparts a most unusual and exotic flavour which is well worth sampling.

Nettles figure in a number of herbal beauty formulae. An infusion of young or dried leaves is supposed to make a very good skin toner and an astrigent bath additive.

It is as a medicinal herb, though, that the nettle really comes into its own, and has been used, with greater or lesser success, in recipes to treat a wide range of maladies, including bronchitis, whooping cough, pleurisy, and other chest complaints; diabetes, dropsy, gout, rheumatism, varicose veins, menstrual problems, diarrhoea, constipation (yes, both!), stomach ulcers, and piles.

Some of these cures are undoubtedly effective in some cases, and the nettle was a highly prized addition to the pharmacopoeia in former times.

In return for all this bounty, our ancestors were able to forgive the nettle its sting. Next time we pass this ruined cottage by the stream and feel like wielding the big stick, perhaps we should do the same.

(Introduction to these pieces; see all)

Plant Odours

Hound’s-tongue flowers

Image: Fornax

The accurate identification of wild plants is not always easy, and the botanist must use all his faculties in trying to track down a name for his specimen. One of the most useful yet unreliable senses is that of smell: unreliable because no two people ever seem to react in quite the same way to the same odour. To quote Linnaeus, the founding father of modern systematic botany: “... a scent which is disgusting to a boy is most pleasing to a hysterical woman. A countryman entering a drug-store turns faint with the scent of the perfumes, but recovers when a heap of cow-dung is presented to his nostrils ...”

Besides which, smells usually defy description. The human sense of smell is not very acute, and our language simply has insufficient words for the job.

One of the strangest and most characteristic odours in the plant world is generated by the foliage of the hound’s-tongue, which smells of mice. For me this invariably generates memories of the north Norfolk dunes where I found my first specimens: a commingling of marram, hot sun, and the resinous drift of the air through Corsican pines. Any description that I attempted of the smell of hound’s-tongue would be coloured by this, and meaningless to anyone else.

Nonetheless, a plant-smell, once learned, can be a powerful aid to the memory, even if this knowledge must remain a personal thing and incapable of being accurately transmitted to others.

Animals have no such problems. They have no urge to classify or analyse, and smell is simply one part of the whole which makes up their existence. In some groups smell is just as, if not more, important than vision or hearing, and this is true of many insects, for whom, in the main, plants produce their rich and bewildering variety of scents.

The chemistry of plant odours is immensely complicated. The scent is produced by the oxidation, on exposure to air, of essential oils. The oils are stored in special glands, whether in the flowers or elsewhere in the plant. Glands may also be found in the outer skin of stems and leaves, or the oils may be stored in capsules deeper in the tissues, so that the scent is only released when the plant is crushed.

In flowers, these glands are on the upper surface of the petals, or on the sepals or bracts if these replace the petals. The oils are produced continuously; in the final stage of manufacture, the fluid is left as a mixture of oil and sugar, and it is not until this mixture starts to ferment that the scent is released.

The fragrance given off by a broad bank of wild thyme or a hawthorn hedge in bloom will carry a long way, in insect terms. One function of plant odours is undoubtedly to attract pollinating insects: the brighter and showier the flower, the less likely it is to have a strong perfume. Certain moths and butterflies secrete scents similar to those produced by plants, and in many cases these insects will only visit the flowers which smell like themselves.

On the whole, though, scent is thought to be relatively unimportant in bringing pollinating insects from a distance. It is much more important at close range. In experiments with porcelain flower-models, insects approached in the ordinary way, but would not enter until the models had been brushed with scent from a real flower. So it would seem that the scent modifies the behaviour of the insect in some manner, encouraging it to go through those actions which lead to pollination.

Another function of plant odours is to serve notice on a would-be browser that the plant is distasteful or poisonous. The chemicals adopted here are often trimethylamine and propylamine, which are present in the early stages of putrefaction, or indol and its related compounds, which likewise have a horrible smell. When the depredations of leaf-cutting insects and their larvae are taken into account, this must be vital to survival.

Protection from attack by fungi and bacteria is equally important: it has been estimated that the essential oil of thyme is twelve times more antiseptic than carbolic acid. The oils of lavender and rosemary are just as strong.

Thyme, lavender and rosemary are all members of the Labiatae, the family of plants which includes many of our best-known herbs, such as basil, mint, and marjoram. Labiates tend to be plants of dry, open ground and sunny places, and as such need some protection against excessive water-loss. As part of their armoury they are usually thickly coated in fine hairs, which help to reduce evaporation from the open pores or stomata on the leaves.

The aromatic oils produced by these plants also help to reduce evaporation. The oils are not soluble in water and create a haze round the plant, reducing water-loss but still allowing the exchange of oxygen and carbon dioxide to continue in the leaves. Labiates often grow clustered in dense patches, and it is intriguing to think that they create their own protective shell using nothing more substantial than odour.

But how to explain the smell of hound’s-tongue? To know that it is caused by esters of certain fatty acids does not get us very far. Nor does it help much to know that the same odour occurs in the entirely unrelated lizard orchid, although both plants are pollinated by bees.

Unless plant-nibbling insects are put off by the smell of mice (or goats, as some people describe it), we are left with as curious a puzzle as could be hoped for. Such are the pleasures of botany.

(Introduction to these pieces; see all)

Bluebells

Image: Wikimedia Commons

Among the many sights and sounds to be treasured from this evening’s walk through the woods and fields is one which never fails to come each spring, yet never fails to surprise.

Each day now the twilight lasts longer and longer, and once the sun had set the thrushes continued singing almost until darkness. A cuckoo was calling very late, and after nine o’clock I passed through the northern end of Harrock’s Wood, where, under the hazels, a seemingly solid yet insubstantial mass of bluebells stretched into the wood for as far as the eye could see, the colour deepening and becoming more mysterious with the dusk.

For those plants which grow in the woodland understorey, the single most important factor is the amount of light available, and most of them, the bluebell included, must get their flowering finished before the full canopy of leaves is out.

In the first half of May the leaves of the dominant woodland trees begin to emerge from the bud-cases in which they have passed the winter. At first the leaves are pale-green, soft, and almost translucent, but they quickly harden as the chloroplasts – the chlorophyll-containing bodies – are brought into use, and within a week or two the tree is a fully functional factory, running on sunlight and producing sugars and oxygen.

The bluebell is tolerant of shade, but does not need it and grows well in full light. The reason it is primarily a woodland flower probably has something to do with the greater humidity to be found inside a wood: bluebells have exacting requirements for moisture, and the soil must be neither too damp nor too dry. They also like ground, such as that in a wood, which remains undisturbed for many years, and the best displays are always found in old-established woodland.

With its blade-shaped leaves and long hollow stalk or scape, the bluebell is a typical member of the lily family – which also contains such oddities as the asparagus, tulip, onion, and garlic. The flowers are bluish-violet because that colour appears most prominent to the ultraviolet-sensitive eyes of the insects which pollinate them, and are carried, up to sixteen at a time, in gracefully drooping, one-sided racemes. The anthers are creamy white, unlike the blue anthers of the garden or Spanish bluebell, Endymion hispanicus.

The wild bluebell is rather puzzlingly called Endymion non-scriptus, or “not written-on”. Gerard, the herbalist, in 1597 described the “Blew English Hare-bels, or English Jacint”, jacint being another spelling of “hyacinth”. Among the ancients, jacint or jacinth was a rare gem of blue colour, probably sapphire. Then, recounted by the poet Ovid, there is the legend of Hyacinthus, a youth “beloved of Apollo”, as the phrase discreetly puts it. Hyacinthus was accidentally killed by Apollo (another version blames Zephyrus, the West-wind), and on the spot where he died a flower sprang up – the lily or hyacinth. On the petals Apollo inscribed the letters AIAI (the Greek word for “alas!”), which can indeed be seen on certain sorts of lily to this day.

The early herbalists tried to describe everything in terms of classical learning. The bluebell was plainly a hyacinth of some sort, and was originally placed in the genus Hyacinthus, but the word AIAI was not to be found on its petals – hence it was non-scriptus.

William Turner, in the third part of his Herbal, published in 1568, recommends the bluebell as a remedy against spider-bite, an idea pinched from the Greek writer Dioscorides, who was anyway describing another sort of hyacinth. Turner also says that the boys in his district “scrape the roote of the herbe and glew theyr arrowes and bokes wyth that slyme that they scrape of”, and indeed the slimy sap of the bluebell can be boiled down to make a strong and practical glue.

This sap covers the fingers of those who indulge in the mindless and illegal habit of bluebell-picking. The peculiar noise and feel of the stems when they are broken has given rise to one of the bluebell’s most vivid vernacular names, “snapgrass”. The Victorian poet Gerard Manley Hopkins writes in his journal: “The stalks rub and click ... making a brittle rub and jostle like the noise of a hurdle strained by leaning against”, which is as apt a way to put it as can be imagined.

He also describes the bluebells making “falls of sky-colour”; bluebells are seen at their best where they grow in sheets and clumps and spread a broad carpet of blue. As soon as they are picked, within minutes, they begin to droop, and in a vase or jamjar at home they look completely miserable and out-of-place. It is much better to leave them for others to admire.

If the truth be told, picking the flowers does less harm than treading on the leaves, which are fleshy and easily damaged. The bluebell spends the dark summer under the trees in renewing the food reserves held in its bulb, and if the leaves are squashed the whole plant will become sickly or die.

Private, relatively untrodden woodland, like Harrock’s Wood, is the place to see bluebells in the mass; but even in overused woods, litter-strewn hedgerows and spindly copses, bluebells in healthy groups are still a frequent sight. Perhaps they are more resilient than they look.

(Introduction to these pieces; see all)

Introduced Trees

In recent years hundreds of thousands of evergreens have been planted by English gardeners, whether for hedging or as specimen conifers. Many of the trees sold here belong to a species called Lawson’s Cypress, which has been bred into a bewildering variety of cultivars and crossed with other cypresses to make such hybrid forms as the Leyland Cypress. The Western Red Cedar or Arbor-vitae is another common kind, and there are several others.

Most of these come from the western seaboard of North America. The climate there is mild and equable and ideal for trees: the giant redwood is one of the most famous inhabitants of the forests at California and Oregon.

Our own climate is also oceanic and in certain ways is even better for the growth of trees. What some people might not guess is that the tiny conifer bought today at a garden centre may – unless it is a specially-bred dwarf form – have the potential to grow to a height of a hundred feet or more.

The suitability of Britain for trees is not reflected in the diversity of the native tree flora. Britain was cut off from the rest of Europe at a fairly early time. This, together with the fact that the ice sheet came as far south as the Thames, combined to deprive us of many sorts of plants, including trees, that are common on the Continent, and our native flora only has about thirty-five species of trees.

However, conditions here are just about perfect for the sustained slow growth which makes the finest specimens, and our introduced tree flora is one of the most varied in the world – containing at least 500 species to be found generally, along roadsides, in parks and gardens, and over 1,200 more in special collections. One such arboretum at Westonbirt, in Gloucestershire, has no fewer than 540 different species.

Once started, tree-watching can become a compulsive hobby. All you need is a good book – trees have the great merit of not running or flying away when you get near them, and can always be revisited with a more knowledgeable friend if you are not sure of your identification.

The charm of trees is not easy to convey in words. Their obvious qualities of permanence, grace and silence lend them nobility. Each species has its own particular style, its own solution to the problem of life, that colours everything it does and every particle of its substance.

When you are examining closely, under a lens, a spray of pungent Incense Cedar, or a shoot of Hornbeam or Silver Maple, you enter another realm where normal scale does not apply. Each leaf is perfection, complete in itself. No matter how many times it is replicated, the quality is maintained, the flavour of the tree remains intact. The flavour extends to the shape the tree makes in the landscape, and here again each species is unique. An expert can tell one kind of poplar from another while passing in the train.

For tree-addicts there is no arboretum locally, and excluding Kew and the London parks, the closest collection of any merit is at the Savill Garden, near Windsor. Nonetheless, you do not have to go far to find unusual trees – probably no further than your nearest street-planting or municipal park.

Cassiobury Park, for example, is the next best thing to Watford’s own arboretum. Especially in the area near the Shepherd’s Road to Stratford Way path, there are many fine specimens of North American oaks – including Red, Pin, and Scarlet Oaks. To the east of this path are specimens of such exotics as Hupeh and Kashmir Rowans, Sweet Gum, Indian Horse Chestnut, and Monterey Pine. Nearby, standing with Cedars of Lebanon, is a young Giant Redwood and, by the croquet lawn, a Japanese Red Cedar.

Further down the hill is a Tulip Tree, and near the paddling pool are many Western Balsam Poplars; by the river, next to the children’s railway, is a single specimen of the Swamp Cypress, a native of the southern U.S.A. and one of the few trees in the world able to thrive with its roots submerged in water. The black, boggy soil by the Gade is perhaps the best place for it but even so it looks ill at ease, like an animal in a zoo cage, and you come to realise that it really has no business there.

However much fascination exotic trees add to the view, there are not many to compete with our own natives in planting schemes, formal or otherwise. The colours of the beech and oak are in complete harmony with the colours of English skies; and to these trees, and to the kind of forest they make, our native animals and lesser plants are completely adapted.

The exotic trees are comparatively lifeless. Some birds, including the Greenfinch, are slowly learning to exploit the sterile conifer hedges, but compare the number of nests to be found in a hedge of hawthorn or yew. Pressure on land is now so intense that there can no longer be much justification for planting alien species.

And, if you are thinking of buying a conifer this weekend, it might be a good idea to leave enough money in your will for your children to buy climbing irons and a pruning saw!

(Introduction to these pieces; see all)

Up from the Pit

Here and there in this region on the edge of the Chilterns the soil consists of marl – a mixture of clay and calcium carbonate which was formerly used as fertilizer. The marl was dug with spades and wheelbarrows and hauled away on horse-drawn carts.

The abandoned pits can be encountered almost anywhere in the countryside. Most are fairly small, no more than fifty or sixty feet across and twenty or thirty deep. Sometimes they are used as tips for broken washing machines, rolls of rusty barbed wire, milk crates, and similar debris. Occasionally they are put to more ingenious use. The golf course green nearest the Iron Bridge in Cassiobury Park, for example, lies at the bottom of an old marl pit, the green itself thus hidden from the golfers on the tee.

In places that pit slopes pretty sharply; as children we used to toboggan there. Other depressions, a few as large, may be found nearby in Whippendell Wood.

The marl was first dug at about the time, a couple of hundred years ago, when the grand landscapers were at work transforming the parks of the wealthy. This was also the heyday of the great furniture makers, whose factories at High Wycombe had an almost insatiable demand for hardwood. These factors combined to ensure the widespread planting of beech – a noble, imposing tree for planting schemes both formal and otherwise, and a valuable source of first class timber.

The grounds and park attached to Cassiobury House are now reduced to a fraction of their former size. In what remains – the present Cassiobury Park, the adjoining golf course, and especially in Whippendell Wood – evidence of this beech-planting can everywhere be seen.

For such a large tree the beech is not long-lived. After two centuries – a mere seventy or eighty thousand dawns – some of the planted specimens are piecemeal beginning to die. They are apt to shed a large bough without warning; it can be dangerous to linger too long underneath.

On the higher and sloping ground in particular the beeches have reached their best. In maturity they are massive, smooth-boled monsters with elephantine limbs and silvery-grey elephantine skin, sometimes bearing scars. A hundred pellet holes from a wanton shotgun blast, unleashed perhaps by a poacher who prowled the woods before any of us were born, have each expanded to the size of a ten-pence piece – or a florin, as he would have called it. The carved hearts and initials of forgotten lovers, expanding steadily with the years, have become indecipherable. One tableau has been so altered by the tree as to resemble the secret markings on some Druid stone, forming the face of a deity: the pagan protector of all things in the woods, not least of them the beech.

The beech nuts, or beech mast, are sometimes, as in this last autumn, shed in such prodigious quantities that they sound like rain in the days and weeks of their fall. They form an important source of winter food for many animals and birds; the population size of such species as great tit and chaffinch can be related directly to the abundance of the mast crop.

Each nut is quite small, half an inch long or so, of a pattern called by botanists “triquetrous”, with three sharp-edged sides and a small rounded base. It opens at the tip in spring and there emerges a creamy white radicle which pushes down into the soil.

Competition among the seedlings is so intense that each has less than one chance in several hundred thousand of reaching maturity. The adult trees blot out the light, spreading a canopy a hundred feet or more overhead, and in the autumn send down a blizzard of leaves which, slightly toxic, inhibit undergrowth of any kind.

Only where a large tree has fallen, or where the ground has been otherwise cleared, do the saplings stand a chance. Then the race is on: the first up to the light is the winner, and the rest are left to die.

This may be seen plainly at one of the old marl pits in Whippendell Wood. Digging there must have been abandoned about a century ago and the soil left to its own devices. Surrounding the pit are veterans of the planting era; at the very edge are several whose roots have grown in a tangle down the slope. These trees are the parents of those that have sprung up in the pit itself.

The young beeches began with a handicap. Some have as much as thirty feet to make up before even reaching ground level. They have grown fast, with smooth, clean trunks, not wasting time or effort on producing limbs. Everything depends on reaching the canopy.

But the older trees have already taken the opportunity of spreading their branches further and further into the gap, greedily consuming the free space. Only one or two of the young beeches in the middle of the pit have any hope left. When existence itself is the prize, even these silent grey leviathans care nothing for their offspring.

(Introduction to these pieces; see all)

Giants and Pygmies

Not far from the lane is an area of the wood which a Georgian forester must have thought suitable for Norway spruce. He may have dreamed of leaving them to his grandson’s son to sell as masts for sailing ships, or simply as the raw material of the new literacy. He planted well; his trees grew strong and tall, but as they grew the markets changed. Steam replaced sail; cheaper woodpulp came from Scandinavia. The trees matured and were not harvested, and yet lived on.

Now many of these giants are reaching their term. Some are dead already, the bark peeling, the exposed heartwood bleaching grey, the roots and base sprouting telltale brackets of white fungus. A few have already crashed, and where the trunks and branches block the rides they are quickly cleared by men with chainsaws. The timber is good for little by that stage; it is probably burned.

In a quiet part of the spruce grove, a few yards from the nearest path, one of the trees, similar to its neighbours in every outward respect, has been singled out by a tawny owl. To the same broken stub of branch the bird comes time after time to rest and in peace and silence digest its meals. This December morning, in the half light of dawn, it is here again. Its great head turns; it blinks, makes a slight retching motion, and brings up a wet grey mass, a pellet of indigestible fur, bone, earthworm bristles, feathers, claws. The pellet tumbles eleven feet to the ground and comes to rest among a score of others of varying age.

Preserved in these capsules is the history of the owl’s diet. If you know how to read them, the fragments of bone reveal much about the small mammals of the wood. Of course, the owl may have its personal likes and dislikes; it is not an impartial sampler. To get information of scientific value requires the dissection of many pellets from many owls over a great period of time, as was indeed done by one zoologist in a clever and original study. Taking these few home in a plastic bag, though, might tell us something, perhaps, that we do not already know.

With a lens and textbook the tiny bits of bone, cleaned now and dry, can be roughly sorted. Skulls in various stages of destruction, halves of lower jaws with or without teeth, assorted molars and incisors. Vole this side, shrew that. A wood mouse skull, or what’s left of it. This lumpy-looking thing is a mole’s humerus. A flat, fluted wishbone: the lower mandible of some dunnock-sized bird.

Among the shrew jaws there are two, both right-hand halves, which are obviously smaller than the rest. And here, in the as yet unsorted pile, is an upper skull barely half an inch in length. It once belonged to a pygmy shrew, the smallest of all our mammals. Handled like this, turned in stainless steel tweezers under a desk lamp, it seems impossible that a skull so small could once have held a mammal’s brain or housed even such a quick, ferocious and hyperactive soul. Shrews do not live for long. Their existence is all aggression, greed, sex, a headlong madness to cram each minute full.

A year or two ago you found one drowned in the greyish fluid that had gathered in the bottom of a discarded preserving jar. The jar had been inside a sack of rubbish dumped in the ditch by a passing motorist. A fox, smelling chicken bones, perhaps, had torn the sack open and out had spilled the jar, coming to rest among the nettles. There it had lain, waiting for the shrew to find it and stumble inside.

That death was easy enough to understand; but what caused the end, last July, of the shrew you found dead in the middle of the path? The body was cool, but still limp. There was no sign of injury or any other cause of death. The nervous system, already running on maximum, may simply have conked out; or there could have been a failure in some vital valve of the perennially over-revved and overloaded heart. A pygmy shrew is miniaturization taken to extremes.

At that size nature is pushing the very limits of design, just as, at the other end of the scale, it is pushing the limits when the huge crown of a long dead spruce, yielding at last in the lifelong fight with gravity, splits off and falls with a thunder that makes the whole forest quake.

(Introduction to these pieces; see all)

In the Valley

They were once the masters of the dank, damp places, undisputed lords of the river. They were magic and to be feared. If you were so brave as to cut one down the stump bled. The timber did not rot. The foliage was dark, the bark black, so black that, even in winter when the leaves had gone, the ground under the alders was always gloomy and oppressive.

The alders were here, of course, thousands of years before we were. Their pollen has been preserved in samples taken from peat bogs; their seed has been found among the earliest remnants of ancient man. At that time the whole of England was one vast forest. The dry ground was the scene of a strange, imperceptibly slow and protracted yet ferocious war of attrition waged between several species of trees. The prize was the possession of the landscape: the winner, in the first age, was the small-leafed lime. Then came men with their animals. Lime leaves were gathered as fodder. The lime’s defences were weakened and in came oak. Oak forest dominated England until the arrival of metal and the growth in the human population signalled its end.

But below all this, in the marshy places, where the soil was too wet to interest the farmers, the alders were yet safe. They survived here using the same weapon that had held off the limes and oaks: a special sort of root system that produces its own free nitrogen and enables the roots to withstand prolonged or even permanent immersion. The roots, together with the unique mixture of sedges and rushes which accompanies alder woodland, gradually consolidate the marsh, raising the level and sending the water elsewhere. Once the best ground higher up had been put to the axe, we began to drain the water-meadows, and to maintain this drainage the alders had to go.

Extensive alder woodland, or alder carr, as it is called, is now virtually unknown in England. The few alders that are left to us are thinly scattered along the margins of lakes and rivers, and only survive there by default. They are given gracious permission to remain, to represent their ancestors in the valleys where once they held sway. There is something sad about them now, as though they cannot forget past glories. The aluminium sign, “PRIVATE FISHING, NO DAY TICKETS, BY ORDER”, the two iron nails unfeelingly driven into the heartwood and allowed to rust, are just another humiliation, too minor even to notice or resent.

Even the river itself has been destroyed, an impossible act in the imagination of the ancestors. It is now a canal. The otters have gone, the trout, the variety of dragonflies. From the old times only the siskins really remain, ever faithful: small, acrobatic finches, streaked green, yellow, and black. With goldfinches and sometimes redpolls and blue tits they make flocks which move through the alder tops, prising the seed from the small, woody, cone-like lanterns of the old female catkins. The seed is rust-coloured and rich in oil, very nourishing for the finches on a dark November afternoon such as this. The siskins are especially busy, preparing for a long and chilly night spent immobile, losing heat, roosting high up in the alder branches. Their cry is a thinner, more metallic, version of the greenfinch’s wheeze, quite unmistakable, even when you and your bicycle are jolting and crunching along the towpath. You stop and look up, hoping for a glimpse of them at work. Alder seed is coming down in sparse showers. The seeds will float away if they hit the canal. Small as they are, much of their surface is given over to two minute waterwings. It must be hard work to eat enough to make a meal, but the siskins do it. In this, like the alders themselves, the siskins are too narrow and specialized. That is why they are relatively uncommon these days, much less plentiful than the goldfinches. The siskins’ diet is virtually restricted to the seeds of alder, birch, and of a few other trees; the goldfinches can take many other sorts of food besides: thistle and burdock seed especially, insects too. And, even among the alders, the goldfinches are more enterprising and opportunistic. At this very spot last winter a party of goldfinches was on the ice, picking up the alder seed where it had fallen. In this way the goldfinches saved themselves their usual exertions, and the food needed no special finding. It was there, spread out as though on a table.

The siskins are moving on. Dusk is approaching and you have only dynamo lights, not the safest way to illuminate rough ground, so perhaps you had better do the same.

(Introduction to these pieces; see all)