Blog Archives: Beth Chatto Gardens

Murder at the Garden Pond: Thalia dealbata – the (not very) beautiful assassin

An evergreen, marginal aquatic perennial forming a clump of long-stalked, erect, narrowly ovate leaves to 40cm in length, covered with white powder, and slender stems bearing panicles of purple flowers 2cm across’. This, from the Royal Horticultural Society, neatly sums up the rather statuesque plant that we encountered in Beth Chatto’s garden last summer: Thalia dealbata.

As per usual, when in gardens we seek out insects to photograph and were immediately aware that this plant was covered in SO many pollinators. But dead pollinators. On closer examination, each flowerhead was actually riddled with corpses – hoverflies, lacewings, bees, wasps and blow flies, amongst others – a glistening mortuary for those valuable garden assistants, pollinators and predators alike, all stuck headfirst into the mouths of their nemesis.

The scale of the carnage was, quite simply, shocking. Some, still alive, like this Honeybee we managed to release, but most were dead. Lost to the world.

Reference to the internet shows this is a recognised phenomenon. The plant has no reason to kill its visitors – it doesn’t digest them like a truly carnivorous species: it seems that the flowers have an elastic style, used in explosive pollination which can and does trap insects.

In its native central American/southeastern USA range it is normally pollinated by large and powerful Carpenter Bees, capable of extricating themselves from the flower’s fatal embrace. Anything smaller is trapped and starves, mere collateral damage, cannon fodder in the battle for life.

 

But at times of an Extinction Crisis, that is one pressure our array of pollinators, necessary not just for the plant’s but for our species’ continued existence, can do without, dozens of pollinator lives being extinguished unnecessarily for each flowerhead. We raised our concerns with the Beth Chatto gardeners, and they promised to investigate, perhaps to remove the spikes of (to our eyes, rather unlovely – they often don’t seem to open fully) flowers, leaving only the stately leaves to give emergent architecture to the water margins.

And to their credit, the Beth Chatto online sales catalogue does at least draw attention to this antisocial behaviour attribute of Thalia: ‘Please note that the plant has an unusual mechanism for pollination which results in some pollinating insects remaining trapped within the flower, where they can perish. Hover flies appear the most affected.’

No other suppliers that we came across made any such references to the ‘special properties’ of Thalia, so we started a bit of a Twitter campaign to raise awareness, and perhaps get restrictions on the sale of the species, or to at least persuade suppliers to inform potential customers of the plant’s fatal attraction. And perhaps in response to this, we note that six months on, the RHS website now contains the following sentence: ‘Although not carniverous [sic] as such, this plant may trap and kill small insects such as hoverflies and small bees during the pollination process.’ Not the unequivocal recommendation not to buy and grow it that we might have hoped for, but a start nonetheless…

The RHS also provides a list of recommended stockists, of which six are noted for Thalia, one in France and five in the UK (including Beth Chatto’s). Two of those seem no longer to list it on their catalogues, but that still leaves three well-known British aquatic plant suppliers who do without hesitation, one even noting it is ‘much frequented by butterflies, moths and other pollinators’ without giving the full story. And of course other UK suppliers are available, though in the first three pages of a Google search, none referred to Thalia’s nasty little habits, save for World of Water Aquatic Centres which in its information table asks ‘Perfect for Pollinators?’, and gives the answer ‘No’, albeit without explanation.

We shall be contacting suppliers to try and persuade them to at least mention this issue, if not withdraw it from sale , in the hope that insects can be saved and eco-conscious gardeners are not upset at the behaviour of their latest purchase. And future updates to this blog may include a ‘name and shame’ as well as a ‘Hall of Fame’!

Beth Chatto Gardens – sunlight and shadows

The winter thus far remains stubbornly at arm’s length, save for a few frost-washed mornings. The crisp blue light of a midwinter morn has been hard to come by too, temperatures held up and spirits lowered by seemingly unremitting gloom.

But at last today the skies cleared and the garden once again came into its own.

Sunlight and shadows….

Seedheads and sprinkles…

Subtle splendours…

And scentwaves and snowdrops.

 

Beth Chatto Gardens: the reawakening of the year

‘Reawakening of the year’ hardly seems appropriate, as hitherto the winter slumber has been barely discernable, with few frosts, and bees and other insects around us all the time. As worryingly now seems to be the norm.

Maybe ‘renewal’ is a better term: last year’s leafy growth is playing its final role as a blanket protecting the coming seasons’ primordia from environmental extremes, before breaking down into the nutrients they need to fulfil their potential…

…while tussocks of grass and other plants again provide shelter for overwintering invertebrates, and sources of food to seed-eaters. In too many gardens – happily not Beth Chattos – these would have been ‘tidied up for the winter’.

New spring greens are already coming through, with added colour from variegations and coloured bark, perhaps more obvious and appreciated at this time when flowers are at a premium.

And likewise now is the time to appreciate the trees for what they are, liberated from the distraction of blowsy flowers all around. Standing for decades, centuries even, like old furniture they are so often ignored, but what a delight they are, hinting at the riches they have already given us and promises for the future.

Structure and texture are best appreciated when the sun shines, and this is when their trunks play a role for the few insects on show, sheltered spots for basking flies, even on a cold day like today.

On a warmer day, no doubt many more insects would have been evident, roused from winter torpor and needing to feed to replenish resources for any cold snaps to come. Herein lies the value of a garden: in January, the countryside is pretty much devoid of pollen and nectar sources apart from Gorse. But in a good garden, the ‘winter nectar gap’ can be closed, an essential feature in these times of climatic disruption.

Moreover, some of those plants have a scent that intoxicates even the most jaded human snout, from spicy Wintersweet to rich Witch-hazel, the delicate lily-of-the-valley fragrance of Mahonia to the ultra-sweet wafts of Sarcococca.

 

Cockaynes Reserve – landscapes, wildscapes and groundscapes dressed in the fires of autumn

The first frosts of winter arrived a couple of days ago, but winds have been light and so the fiery hues of autumn remain around Cockaynes Reserve for now. From trees to reedbeds, leaves are bronzing as if to intensify the feeble sunlight, although today it wasn’t making much impression on the cool easterly air-flow…

Wildlife was of course hiding away, as often as not in plain sight: almost everything we saw seemed to be painted in the palette of decaying chlorophyll, from all manner of fungi to seeding Reed heads to Feathered Thorn:

And then there were the Groundscapes, the pattern of leaf-shapes and colour beneath each species of tree, as distinctive now as at any time of the year. For me, these unique combinations are the shroud of the passing year: here lies Field Maple, Silver Birch, Ash, Sweet Chestnut, Hornbeam, Oak and Hazel.

The Beth Chatto Gardens throughout the Seasons: September

Summer returning with a flourish, sun streaming from a cobalt sky, but the signs are there… autumn is upon us, the leaves are turning. And also falling, seemingly on the early side, perhaps one result of a droughty August.

Before the fiery flames of high autumn sweep through Nature’s realm, delicate pastel shades  are more to the fore…

…with colour-bursts and blasts to remind us of the summer now departed.

A lower sun extracts hues, textures and patterns from the garden that may otherwise be missed.

Still plenty of nectar and pollen sources around…

…and insects to take advantage.

Others basking wherever they can, to warm up enough for the the final act, their legacy, producing the next generation. It was especially good to see several shrubs festooned with the metallic green matchsticks that are Willow Emerald damselflies, only recently established in Britain, but now a reliable feature of early autumn here.

 

In the wider countryside, Ivy is the final main course of the season, its flowers vats of nectar and pollen, enveloped in a heady, sensual, musky poll of scent, and the persistent hum of a myriad of visiting wings. Even with blowsy blossoms as a distraction, the allure of Ivy which has decided to make the garden its home still pulls them in.

Down at the ponds, Thalia, that (not very ) beautiful assassin (see last month’s blog), is still exerting its fatal attraction.

Spiders too are taking their toll on the insects, but at least they – unlike Thalia – eat their victims.

And it was particularly exciting to be shown a Wasp Spider which has taken up residence in the Dry Garden, feasting on the local grasshoppers. While not uncommon in rough grassland right by the estuary, this is the first time we have seen it in the Beth Chatto Garden, a space for plants and all that they encourage.

 

The Beth Chatto Gardens throughout the seasons: August

High summer, those languid, lazy days of sunshine and leisure…if you are human. But for the rest of the world, a time of frantic activity, flowering, seeding, feeding and breeding. Many of the flowers are fading, evidence their job is done, though some like Echinacea and Asters reserve their finest show for the later months, just as the throngs of insects need it the most.

And what a range of insects and other invertebrates, from butterflies and bugs to micromoths and flies, with as always spiders taking their share:

But  wear and tear on leaves is also a positive sign, indicative of the feeding activity of those mobile garden adornments which will bring movement, excitement and joy to next year’s borders.

Down by the water’s edge, summer was only just bursting, with swathes of colour, and flashes of magic from dragonflies and damselflies.

But all was not as serene as it seemed. Large clumps of flowering Thalia dealbata in the ponds were clearly a magnet for insects of all sorts, hunting nectar and pollen…

…but on closer examination, each flowerhead was riddled with corpses – hoverflies, lacewings, bees, wasps and blow flies – a mortuary for those valuable garden assistants, pollinators and predators alike, all stuck headfirst into the mouths of their nemesis.

The scale of the carnage, was quite simply shocking. Some, still alive, like this Honeybee we managed to release, but most were dead. Lost to the world.

Reference to the internet shows this is a recognised phenomenon. The plant has no reason to kill its visitors – it doesn’t digest them like a truly carnivorous species: it seems that the flowers have an elastic style, used in explosive pollination which can and does trap insects In its native central American range it is normally pollinated by large and powerful Carpenter Bees, capable of extricating themselves from the flower’s fatal embrace. Anything smaller, mere collateral damage, cannon fodder in the battle for life.

But at times of an Extinction Crisis, that is one pressure our array of pollinators, necessary not just for the plants but for our species’ continued existence, can do without, dozens of pollinator lives extinguished unnecessarily for each flowerhead. The Beth Chatto online sales catalogue does at least draw attention to this antisocial behaviour of Thalia, but none of the other websites I have visited, nor the RHS make any reference to it. Time for a campaign, maybe a ban, but at least removal of the flowering spikes before they open. It’s not as if they are especially attractive, the main value of the plant being its architectural emergent foliage.

On a happier note to end with, one of the great advantages of being naturalists is that people bring us specimens. And so it was today when a proffered pot revealed its treasure, a Tanner Beetle Prionus coriarius that the Education Team had just found, something that neither of us had seen before.  A large, blackish longhorn, it is considered to be rather rare in Britain, found at scattered localities in the south of the country, and is usually associated with ancient woodland or extensive natural landscapes like the New Forest. Its larvae, like those of Stag Beetles, develop over several years inside rotting wood, and the National Biodiversity Network map shows one previous record close to Elmstead Market, but very few others in and to the east of Colchester.