Sunday, 9 February 2020

Willows

The classic outline of stately White Willows (Salix alba) in the Yare Valley at Buckenham, Norfolk
We probably all have a clear image in our minds of what a willow is when we hear mention of this group of plants. Most people will immediately envisage a large tree on a riverbank, perhaps leaning out over the water and casting interesting shadows and reflections. Some may also picture the wonderful golden colours of a weeping willow beside an ornamental duck pond. While these are classic images of willows, this group of plants also includes lower, bushy plants - collectively known as sallows - which are plentiful in almost any type of wet ground and are often the first woody perennials to colonise damp ground that has been cleared or is drying out due to habitat succession. And there are even smaller species - less than waist high - that grow in coastal dune habitats, while high in the Arctic, willows hug the ground to cope with extreme growing conditions.

A low, spreading mound of Creeping Willow (Salix repens) in the dunes at Holkham, Norfolk

Globally, willows are surprisingly variable. In the high Arctic, Net-leaved Willow (Salix reticulata) grows to barely 10cm in height and produces little, upright catkins above whorls of rounded leaves. I photographed this one a few years ago in Alaska, USA.
Willows are related to poplars and share a few features with them, such as the presence of stipules at the base of the young leaves and petalless flowers that are wind pollinated and clustered together in catkins. Male and female flowers appear on separate plants and those of the sallows seem to be especially popular with bumblebees in the spring.

This close-up of an Almond Willow (Salix triandra) stem shows one of a pair of leaf-like structures known as stipules. These structures are a useful feature in a handful of plant families and can help with species identification.
Male catkin of Goat Willow (Salix caprea). Each single flower is topped with yellow stamens; the number of stamens per flower can sometimes by useful for identification.
Female catkin of Grey Willow (Salix cinerea). Each single flower is accompanied by a dark bract and topped with the two-lobed, cream-coloured stigma.
The species of willow that occur in East Anglia are mostly fairly easy to tell apart, but identification of the sallows is complicated by the freedom with which the various species hybridise. These hybrids can be fertile and further hybridise with other species, potentially creating a bewildering array of forms. We have many uses for sallows and their wood and for this reason, hybrids have been produced commercially and are widely planted in the countryside, further complicating the issue for the would-be botanist. Sometimes, it can be very tempting to quietly move away and go and look at something else!

The golden curtains of branches are very attractive and make Weeping Willows (Salix x sepulcralis) a popular choice next to water in large gardens, parks and municipal plantings. A number of these trees can be seen along the banks of the River Wensum in the centre of Norwich.

Sunday, 26 January 2020

Populated by Poplars!


Straight lines of Balsam Spire Poplar are a common sight in the East Anglian region, where they are widely used for windbreaks, shelterbelts and screening.

Wherever you go in East Anglia, it's difficult to not be within sight of a poplar or two. These trees have long been popular (sorry!) as a source of quick-growing timber and most species do best in damp soils, so the open expanses of the Broads and the Fens were obvious places for them to be planted in large number. Indeed, Britain's largest poplar plantation once existed in Lakenheath Fen - some two square miles of planted poplar hybrids which became famous for its population of breeding Golden Orioles for a while.

Poplars have long been useful to mankind and this has resulted in much time and investment in producing ever more useful forms. The horticultural industry has produced an array of hybrids, in particular by crossing North American poplar species with the European Black Poplar and the resulting hybrids have been crossed again with each other to produce startlingly vigorous trees. In more recent times, efforts have been applied to producing varieties that are more resistent to certain diseases of poplars with the result that many trees we might find in the wider countryside cannot safely be identified to variety, but they can still be recognised as being Hybrid Black Poplars.

Patterns of diamond-shaped studs are an attractive feature of some poplars, including our native European Aspen.
Most poplars that you come across in East Anglia will be planted hybrids, or selected varieties of introduced species. As well as the varieties that are grown in regimented ranks in plantations on wet soils, other varieties are used as fast-growing screens to hide unsightly industrial buildings from residential areas, or as windbreaks to protect crops or to shield sports grounds. In the case of windbreaks, narrow, columnar varieties are typically selected.

But, as well as all these fast growing hybrids, we have our own native species. The European Aspen can still be found in many woods and along old green lanes and hedgelines across the region, especially on the heavier boulder clays that cover much of south Norfolk and mid Suffolk. Aspen suckers freely and can form open thickets, its leaves being very eye-catching as they tremble in the wind - hence the saying 'quaking like an aspen'. Our other native species is the Black Poplar, a species for which East Anglia holds a significant proportion of the British population. Black Poplars became very rare at one point and efforts were made to boost the population with new plantings. So young trees can now be found quite widely in the region, but the venerable old grandmothers and grandfathers are very much worth seeking out for their individuality and beauty. They stand like wizzened old people, singly in hedgerows and on village greens, or in small groups in the broader river floodplains.

The vast majority of native Black Poplars in our region are male, while female plants are very rare. This may at least in part be due to the intolerance of some people to the clouds of fluffy seeds that the female trees produce. This characterful old lady stands on the common at Old Buckenham, Norfolk.
Poplars are at their best in spring when they are at their most vibrant. First the flowers emerge - little catkins that dangle from the branch tips and waggle in the wind like lamb's tails. Poplars are wind-pollinated, so their flowers are highly mobile to allow the pollen to shake out easily, while they tend to appear before the leaves so that there is less hinderance to pollen distribution and reception. All poplar trees bear either male flowers or female flowers, but not both. The species poplars will have both male and female trees out there in the landscape, but hybrids that are named, selected clones will all be of a single sex and this can help with their identification.

Female flowers of Black Poplar. The female catkins tend to be a little shorter and less mobile than the male catkins and are greenish yellow in colour. 
A close-up of a female catkin reveals the swollen, creamy-white tips to the stigmas, waiting to receive airborne pollen from the male flowers.
Male flowers of Hybrid Black Poplar. The male catkins are dark red in colour due to the colour of the stamens which make up the bulk of the petalless flowers. The catkins are long and highly mobile in the wind, which ensures that the pollen gets shaken out easily.


Soon after the poplar flowers come the leaves. Many of the poplar hybrids have leaves that are washed with rich shades of copper, pink or yellowish-brown and really stand out in the landscape at this time. The leaves gradually become green as they open, but continue to be eye-catching as many of them have flattened leaf stalks that cause the leaf to bend against the wind in a certain way and thus flutter in the breeze.

The bronze- or copper-tinted, emerging leaves of poplars are eye-catching in spring against the backdrop of greens from other plant species. These Hybrid Black Poplars along the River Lark in Suffolk are probably the cultivar 'Robusta', which is particularly colourful in spring.

Poplar time will soon be on us, so I've just put up the poplars page on the website:

http://webidguides.com/_templates/treegroup_populus.html


My favourite East Anglian poplars - the group of old Black Poplars on Icklingham Plains in Suffolk are a wonderful sight.

Wednesday, 20 November 2019

Umbel Mumbles...

Over the past, well, what seems like an eternity of weeks, I have been gradually cobbling together - amid much muttering and mumbling - the pages for the Flora of East Anglia website that cover the Apiaceae. That might sound like an unfamiliar name to some, as it was only within the past few years that the Carrot Family had its scientific name changed from the Umbelliferae to the Apiaceae. The Umbelliferae was certainly a more useful name, since it aludes to the distinctive flower structures of this family - a many-branched cluster that rather resembles the shape of an umbrella that has been turned inside out by the wind.

The carrot family is quite a large family of plants that is well represented in East Anglia and many who have tried will know that identification of the many species can sometimes be tricky. Thus, it has taken a while to try and come up with pages that will help people get to the correct identification and I may well tinker some more to make improvements over time. But for now, I think the pages seem to work quite well.

East Anglia would certainly be a different place without its carrots, parsnips, parsleys, hogweeds and associated species. The family contains a wealth of species that seem to span every habitat - often dominating the scene during their respective flowering periods. And though these species may often all seem to look the same, it is also a family of great diversity, from herbs and root vegetables to some of our most poisonous plants and most pernicious weeds! So here's a series of photographs that celebrates the exuberance of our wonderful umbellifers...

From the rarest of plants to the commonest, the open, spreading heads of massed, tiny flowers are readily recognisable and provide nectar and pollen for a huge variety of insects. Though this may seem like a familiar sight, this flowerhead belongs to perhaps our rarest umbellifer - Cambridge Milk-parsley, a species that survives in just two or three wetland sites in Cambridgeshire and which live under constant threat of their special habitats drying out and being lost for ever (Cambridge Milk-parsley, Chippenham Fen, Cambridgeshire).
Spring wouldn't be spring in East Anglia without the exuberance of Cow Parsley along a thousand miles of byways and highways. April and May belong to Cow Parsley, but other species flower later and the timing of flowering can be a useful part of the identification process (Cow Parsley, Burnham Marshes, Norfolk).

While the riotous mass of Cow Parsley flowers smothers our lane sides, a subtler sheet of knee-high whiteness appears in traditional grassland meadows and thoughtfully maintained churchyards. Spring is also the time for Common Pignut, a plant once collected for its edible root tubers. There are few places where a true carpet of this species can still be seen but it still remains widespread in the region (Common Pignut, Felbrigg Hall, Norfolk).

Can you get more 'Norfolk' than a shiny wall of Alexanders leaves in front of a flint-walled church? Despite its association with and abundance in East Anglia's coastal areas, Alexanders was originally introduced to the UK by monks for use as a salad crop. Changes in annual temperature seem to be benefiting this species and over the past 20 years or more it has been progressing inland and is already proving problematic in the preservation of some roadside nature reserves (Alexanders, Walcott Church, Norfolk).

Some plants have a less affectionate place in our hearts than the mass flowering of Cow Parsley. There can be few - if any - gardeners who have not cursed the day that Ground-elder found its way into the garden or allotment. Most umbellifers form a discreet root that sends up an individual crown of basal leaves and upright, flower-bearing stems. But Ground-elder has a mass of yellowish rhizomes that creep freely below the surface and produce a smothering mat of leaves (Ground-elder, Northrepps, Norfolk).

This family has contributed greatly to the kitchen, as well as to the medicine cabinet. Many species are still popular, such as Fennel, Coriander, Dill, Carrot, Parsnip and more, but others have somehow fallen by the wayside and survive now as curiosities of the past. Northern Angelica in one such species and is still occasionally grown in larger flower borders or historical plant collections, from where they might occasionally sneak out into the wider countryside for a time (Northern or Garden Angelica, Apothecary Garden, Norwich Cathedral).

The mass flowering of 'carroty things' seems to take place everywhere, and yet often involves some very habitat-specific species. While this might seem like a familiar scene, Fine-leaved Water-dropwort is rather fussy in its requirements and only really does well in ponds and depressions that are seasonally wet in winter and spring and dry out in summer. It does particularly well in the fascinating, glacial depressions of Breckland known as pingos (Fine-leaved Water-dropwort, Thompson Common, Norfolk).

Rock Samphire is an unusual umbellifer in that it has developed fleshy, succulent leaves that enable it to survive in salt-laden habitats without being desiccated. It favours rocky coastlines so is more common along Britain's western shores, but it finds a niche on some of the more stable sections of shingle beach in East Anglia (Rock Samphire, Felixstowe Ferry, Suffolk).

Wetlands provide a home for quite a number of our native umbellifers. Perhaps the most obvious in such places is Common Angelica, a stately plant that may reach over two metres in height in wet meadows along river valleys and in wet woodland (Common Angelica, River Bure, Aylesham, Norfolk).

In contrast to the widespread Common Angelica, Cowbane is very much a special plant of the East Anglian Broads, where its saw-toothed leaves are a feature of wet dykes and channels in well-managed, species-rich fens (Cowbane, Catfield Fen, Norfolk).

Getting photos for the website certainly tested my commitment at times! River Water-dropwort was proving a difficult species to photograph for a long time as it likes to grow fully submerged in permanent water courses and can take a little finding. Once found, there's the issue of getting the photographs without ruining the camera! The summer of 2018 saw a prolonged dry spell and water levels dropped well below the norm, allowing a not too soggy wade out into the River Yare for some atmospheric shots (River Water-dropwort, Marlingford, Norfolk).

At the opposite end of the wetland spectrum to the deep water habitats of River Water-dropwort, it seems that the sprawling, leafy stems of Fool's Water-cress are happy pretty much anywhere there's some damp mud to collapse onto! This is a plant that copes well with a wide range of wetland situations and can be found even in muddy ditches beside main roads, complete with old tyres and oily run-off! (Fool's Water-cress, Kelling Quag Lane, Norfolk).

High summer sees a whole new suite of umbellifers appearing and a second flush of colour in grassland habitats. At this time of year, it's Wild Carrot that dominates the scene, a smaller plant than Cow Parsley and a widespread species in many types of dry grassland habitats along roadsides, churchyards, clifftops and similar places (Wild Carrot, East Ruston, Norfolk).
High summer sees our region's coastlines hosting the feathery, aniseed-scented foliage and yellow flowers of Common Fennel. This plant is popular for flavouring fish dishes and does well in grassy places near the coast and on tidal river walls (Common Fennel, Felixstowe Ferry, Suffolk).

As well as an abundance of Common Fennel, East Anglia's coastal river walls provide a home for one of our rarest umbellifers with one of the best names - Corky-fruited Water-dropwort! This unassuming plant has persisted, despite much change and development in the area, for many years on an unremarkable stretch of grassy bank while the citizens of Ipswich pass to and fro within easy reach on a daily basis (Corky-fruited Water-dropwort, Belstead Brook, Ipswich).
The umbellifer family has its darker side, with a number of poisonous or potentially injurious species lurking in its midst. Most infamous, perhaps, is Giant Hogweed, a species originally introduced to this country as a garden curiosity. Especially in hot weather, the caustic sap of this species can leave rupturing blisters and chemical burns on bare skin and much time and effort has gone into controlling its spread. It still persists along overgrown sections of the major rivers and on waste ground, but hopefully efforts to contain it are paying off. Despite its reputation, it is nevertheless a wonderfully architectural plant and the initial interest in it is easy to understand (Giant Hogweed, Overstrand, Norfolk).

Hopefully this post gives you an insight into this fascinating family and you will be out next year, exploring East Anglia's wildlife riches and dipping into the Flora of East Anglia to check up on your identification skills!


The joys of spring - Cow Parsley in abundance in a North Norfolk village.

Friday, 5 April 2019

Catkin Time!

The word 'catkin' seems to derive from an old Dutch language and translates as kitten - the diminutive of cat. Catkins are common as the flower structure type for many of our trees and early country folk readily identified the furriness of these structures and compared them to furry animals. Indeed, the term 'pussy willow' for the furry catkins of sallows has the same root, while the longer, dangly catkins of trees such as Hazel and birch are also known as lamb's tails - again, a comparison with the familiar.

So why do we see a sudden mass of catkins on such a wide range of trees at this time of year? They are, for example, common amongst the oaks, beeches, hazels, birches, willows and poplars, as well as a few smaller groups of trees. What's the connection and why now? Well, trees are often large and stand head and shoulders above other vegetation. This puts them up into windier locations than those enjoyed by smaller plants - so why not use that to your advantage? Many trees are wind-pollinated rather than insect pollinated; to facilitate this, they produce huge volumes of pollen, since this is a rather random method of getting pollen from male flowers to female flowers; producing huge amounts will increase the chance that pollen will find its rightful destination. Another way to aid this distribution method is to have freely articulating anthers that waggle in the wind and thus shake out the pollen. So we see many species of trees having loosely connected rows of anthers, arranged in pendulous spikes that waggle in the wind. As an aid to encouraging cross-fertilisation with another tree, trees that produce catkins have the male and female flowers carried separately, with the females typically being much smaller and not pendulous. Most of these trees carry male and female flowers separately but on the same tree; but some species (notably the willows and poplars) have male and female flowers on separate trees.

But why are so many of them around right now? Well, if pollen is being shaken out into the wind to be carried afar, it helps to have as few obstacles in the way as possible. So deciduous trees produce their catkins in the spring, before leaves clothe the branches and get in the way.

Here's a few examples of the catkins that will be dangling away in our countryside this spring:

Hazel (Corylus avellana) catkins are perhaps the original 'lamb's tails' and smother the branches in late winter or early spring (some optimistic individuals appear before New Year's Day!)

Silver Birch (Betula pendula). Birch catkins are rather similar to those of Hazel, but appear later in the year with the first leaves - often not until late April or even early May - and are spotted with dark bracts.

Female Silver Birch catkins start life as an erect spike, with reddish stigmas poking out between the green, protective bracts. The become pendulous as the seeds develop.

Hornbeam (Carpinus betulus) is a member of the birch family and this can be seen in the structure of the male catkins, which have the pollen-bearing anthers protected from the worst of the weather by a series of bracts. 
Female Hornbeam catkins are quite different from those of birches - and very different from the male catkins. They have relatively large, leafy bracts with silky hairs that protect the white, hair-like stigmas from bad weather.


European Beech (Fagus sylvatica). Beeches have rather short, oval catkins, but they hang on long stalks that project them away from the unfurling leaves. Here you can see three male catkins on the left, with their now withered and spent anthers, then a chunkier female catkin to the right, with its 'brush' of hair-like stigmas.

The male catkins of Common Oak (Quercus robur) are typical of most oak species. They are looser and more open than the catkins of other tree families and hang in bundles rather than singly. These should be appearing in about another two weeks time, in mid-April.
Black Poplar (Populus nigra ssp. betuloides). These are the female catkins of our native Black Poplar, a rather rare species in the UK, although a recent trend to plant more has boosted the population. Poplars carry male and female flowers on separate trees and this can be useful if you find one of the many hybrid poplars that abound in our landscapes. Hybrid poplars mostly derive from deliberate cross-pollination of various forms, or selections from a range of plants to produce named clones which are all identical and propagated vegetatively. Thus, whether the tree is male or female (as determined by the flowers) is a useful part of the identification process should you find one of these.

Male catkins of native Black Poplar. The male catkins of black and hybrid poplars are red due to the colour of the pollen-bearing anthers. Poplars have the annoying habit of growing tall and flowering towards the top of the tree, but the difference between male and female catkins can be told with binoculars or by looking for fallen catkins on the ground.

Close up of a female catkin of Populus x canadensis 'Regenerata' - a widely-planted variety in East Anglia. Each bract has a whiskered fringe and has beneath it a swollen, whitish stigma, sticky and waiting to receive wind-blown pollen.

Close up of a male catkin of Populus x canadensis 'Robusta', a spreading, imposing cultivar. Beneath each fringed, whitish bract can be seen a cluster of purple-red anthers full of pollen.

The Goat Willow or Great Sallow (Salix caprea) is a common native of damp woodland and also widely planted. It is one of several shrubby willow species that is referred to as 'Pussy Willow' when the catkins first emerge, covered in silky hairs. Here, the yellow male anthers have now pushed through the silky hairs and changed the appearance of the flower head.

Female catkins of Grey Willow or Grey Sallow (Salix cinerea). Female willow catkins tend to appear narrower than the catkins of male plants as they don't have anthers that need to be pushed out into the wind. Here you can see that the silky flower head is studded with pale, greenish stigmas.

Just to show some willow variety, here's the more slender male catkin of Purple Willow (Salix purpurea), a less common species than the other sallows above, but still fairly frequent in Broadland and parts of Breckland.

If you are into solitary wasps and their intriguing life-styles, catkins can provide plenty of entertainment. These swollen lumps are not fruits, but galls, caused by the presence of tiny cynipid wasps that lay their eggs in the flower clusters and leave their larvae to develop inside. These galls are on the male flowers of a large Lucombe Oak (Quercus x crenata) in Earlham Road Cemetery, Norwich - a place where I shall be leading a tree walk later in the year!




Sunday, 10 March 2019

Daphnes - A Heady Scent of Spring

The Daphnes are hugely popular as garden ornamentals and this is largely due to the remarkably strong scent of their flowers, which comes right at the time when we all need a break from the weather. We have two native daphnes in the UK - the deciduous Mezereon (Daphne mezereum) and the evergreen Spurge-laurel (Daphne laureola) - and they both flower from February to March. Both these species can be found in East Anglia, but only Spurge-laurel appears to be native here, with Mezereon favouring limestone soils elsewhere in the country.

Now is the time to get out and look for Daphnes, so I have just added them to the Flora of East Anglia website pages!

The native Spurge-laurel has greenish flowers that are tucked in amongst the leathery, evergreen leaves - perhaps to protect them a little from frosts. But their subtle appearance belies their wonderful scent which is always a real treat in the late days of winter or early in spring. I often find these while there is still snow on the ground - although maybe not this year!

Mezereon is perhaps the best known of our daphnes, since it is hugely popular as a garden plant. The intensely purple-pink flowers of Mezereon look stunning when they appear on bare stems, before the leaves open. A good colony of these plants grows on a protected reserve in West Suffolk but was most likely introduced; either planted by a well-meaning person or perhaps bird sown from berries.

Mezereon flowers are followed by a second colourful display, provided by its shiny berries that start off green and turn bright red. These are much favoured by birds and occasional plants that pop up around our region perhaps originate from berries that have passed through an avian gardener!

As we come into the final year of field work for the BSBI's Atlas 2020, I am reminded that there are always surprises to be found out there, as the natural world never stands still. In spring 2017, a group of us in the Norfolk Flora Group working on recording for Atlas 2020, came across a number of plants of Twin-flowered Daphne (Daphne pontica) in woodland to the West of Norwich. How these came to be here, we've no idea, but they were well-established and had clearly been present for some time. It's possible that someone planted them to provide berries for Pheasants, but it seems an unlikely choice of species for that, so perhaps they simply found their way there via the local bird population from a nearby garden. This is a new species for the county list and certainly an unexpected find!