Early autumn ‘berries’ in black and white - Dr Terry Mabbett

EARLY autumn is a time for berries in all shapes, sizes and colours. From large, spherical sloes on blackthorn bushes, with an attractive blue hue, to smaller, ovoid and distinctive deep-red haws setting hawthorn hedges aflame in September. Less colourful but in sharp contrast are the jet-black berries on Britain’s most ubiquitous native shrub, alongside the snow-white berries of a naturalised exotic shrub native to North America. 

Be that as it may, blackberry (rubus fructicosus) has much in common with common snowberry (symphoricarpos albus), despite the stark contrast in fruit colour and the 3,500 miles or more which separate the native distributions of the two species.

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Other names for snowberry such as ‘ghost berry’ and ‘wax berry’ are similarly based on its appearance. Bramble is a commonly used synonym for blackberry, but not at all specific because it covers any prickly and rambling shrub of the plant family Rosaceae (rose). As such, 'bramble' may cover blackberry, raspberry and dewberry, and in some quarters even dog rose. 

In Britain, bramble means blackberry, but usually when R. fructicosus is in its well-known weed mode as a prickly, thicket-forming species. But bathed in September sunshine, full of fruit and with the prospect and promise of fruit pies, R. fructicosus is called blackberry. 

As an exotic species introduced from North America for ornamental purposes in parks and gardens, snowberry is treated in a more revered manner. This despite snowberry having its own invasive-weed credentials, like bramble due to highly efficient reproductive systems.

All that said, bramble/blackberry and snowberry each play positive environmental and conservation roles as nectar sources for pollinating insects, fruit for small mammals and shelter for a wide range of birds.

BRAMBLE/BLACKBERRY RUBUS FRUCTICOSUS

Aggregate fruit of Rubus fructicosus are composed of multiple druplets. The fruit grow mature and ripen from green through red and finally black

Rubus fructicosus is native to Europe, including the British Isles, but has a presence across the entire temperate world, often as an invasive weed competing aggressively with native plant species. R. fructicosus is a regulated noxious weed in Australia, New Zealand and USA. 

Such is the colonising capability of bramble that this typically tangled and rambling shrub does not reserve its invasiveness to areas outside of its natural distribution. Native bramble in the British Isles presents land owners and managers with one of the hardiest and hard-to-manage invasive weeds.

Bramble sends strong suckering roots down into the soil and long stems called canes above ground to arch over, under their own weight, and readily root where the node tips touch the soil. The arching stem of bramble is called a stolon and is by definition a creeping horizontal, plant stem or runner which can root at the nodal points (nodes) along its length. 

The bramble stem or stolon is a thick-walled structure with a pithy, porous centre and sharp prickles along its length, initially green/purple in colour but becoming increasingly browner and fibrous with age. Compound palmate leaves have three or five (occasionally four) oval leaflets borne on short stalks, with serrated margins. The deep-green of the upper (adaxial) leaf surface contrasts sharply and starkly with the whitish lower (abaxial) leaf surface. Leaf stalk and mid-ribs (main veins of the leaflets) are all prickly.

Bramble prickles are for the most part distinctly backward facing, narrow and needle-like at first but broadening with an increasingly wide base as the stem ages. Like the stem itself, the prickles are purple in colour indicating presence of high concentrations of the anthocyanin pigment which gives the fruit their red and finally ripe black colouration.

Like the stem itself, they become browner with age to eventually take on a bleached appearance.

Don’t be tempted to call bramble prickles ‘thorns’ or ‘spines’ because they are not. The prickles on bramble and dog rose are actually rigid, sharp hairs which are an extension of the cortex and epidermis of the stem, whereas thorns (e.g. blackthorn) are modified branches and spines (e.g. gorse) are modified leaves.

Bramble stems start life green before turning purple and finally going brown and drying out

In contrast to plentiful and viscously sharp prickles, brambles bear one of the most enchanting summer flowers seen in our woodland. Large clusters of white or pastel-pink flowers 20-30 mm in diameter start to appear in late spring and continue to do so well into late summer. 

Flowers are actinomorphic and conform to the floral geometry of the plant family Rosaceae with five sepals, five petals and many stamens. An actinomorphic flower is characterised by a high degree of symmetry. It can be divided by more than one line through the middle of the flower and into two equal parts which are mirror images of one another.

The insect pollinated and fertilised flowers of the bramble bush develop into fruits commonly called blackberries which mature and ripen from green through red and into black when the first fruits ripen towards the end of July. The number of druplets on a blackberry fruit varies according to size with reports of up 75 or more.

BLACKBERRY IS NOT A BERRY

The term berry is used as a loose name for any soft and fleshy fruit, which the blackberry clearly is, but in botanical terms the blackberry or bramble fruit is a drupe (but a special kind of drupe as an aggregate fruit composed of many druplets).

Drupes and true botanical berries are composed of three layers: an outer pericarp (the skin), a mesocarp and an endocarp. Drupes have a fleshy mesocarp but a leathery or bony endocarp surrounding the seed, usually one seed but sometimes several although only one is viable. A true botanical berry has a fleshy mesocarp and endocarp and by definition (as a botanical berry) must contain multiple seeds. Cherry (prunus) and olive are classic examples of fruits defined as drupes while blueberry and cranberry are classic examples of true botanical berries. The blackberry is clearly not a good example of a drupe because the aggregate character of the fruit muddies the water even more.

BRAMBLE – THE GOOD, BAD AND UGLY

In contrast to an aggressive growth habit and fearsome prickles Rubus fructicosus bears big clusters of delicate flowers and highly attractive to the human eye as well as nectar seeking, pollinating insects

Rubus fructicosus is just one of many Rubus species important for its wildlife and conservation value within the native range, which includes the United Kingdom. Bramble is visited by large numbers of insects seeking and sourcing nectar, and pollinating flowers into the bargain. Visiting and foraging insects are dominated by honey bees and bumblebees, although butterflies are the most colourful. 

A broad range of British butterflies including small tortoiseshell, red admiral, peacock, gatekeeper and speckled wood have been recorded as visitors to bramble flowers. Late season butterflies can also be seen nectaring on over-ripe blackberries in late summer and early autumn. The ripe fruit are eaten by a range of wild mammals, big and small, including dormice, wood mice voles, squirrels, badgers and foxes. An even greater number of birds feast on blackberries beginning in August, including blackbirds, thrushes, starlings, wood pigeons, jays, finches and pheasants. 

Bramble thickets provide good cover for hedgehogs and even good natural cover for game birds. During spring and summer the bramble thicket offers ideal nesting sites for ground nesting and low-nesting birds including wrens, robins, hedge sparrows, nightingales and whitethroats. The biggest and tallest bushes and thickets will tempt blackbirds and thrushes.

Wildlife clearly embraces native bramble, but humans, who are mindful of its prickly presentation and reputation, are understandably wary. I know a tree officer who puts this caution to good effect to preserve the integrity of ancient urban woodland in South Essex from excessive footfall. Hangman’s Wood at Little Thurrock, Grays in the Unitary Authority of Thurrock, which hugs the coastline along the Essex side of the Thames Estuary, has SSSI (Site of Special Scientific Interest) status as home to one of largest bat roosts in the country. The bats roost underground in Deneholes created by medieval chalk mining. 

A bramble thicket which started life as a seedling under a tree which it has now subsumed

Thurrock’s tree officer Liz Wood ensures bramble is mostly left intact to deter dog walkers and others from straying too far from the woodland rides, minimising footfall damage to the woodland. Of course, exceptions have been made, such as when bramble was cleared around veteran oak trees prior to carrying out soil de-compaction work. 

The only time we are not overly cautious about the bramble’s prickly nature is when its arching stems are loaded with luscious black fruit for pies, crumbles and conserves. But a 19th century English poet had some mocking words for the human fruit forager:

To rob the little birds,
Of hips and pendant haws
And sloes, dim covered with dewy veils,
And rambling bramble-berries, pulpy and sweet,
Arching their prickly trails,
Half o-er the narrow lane

From the poem ‘Autumn’ by John Clare (1793-1864).

But bramble has refused to remain within its native range. R. fructicosus, along with many other similar Rubus species, has spread around the world as invasive weeds. Even within its native European range, R. fructicosus graduates from a status as useful wild plant to invasive weed by going wild, invading man-made environments including coppiced woodland, pastures, parks and gardens. 

Landowners and managers have two separate control options, although neither on its own is at all satisfactory. Cutting back to ground level will offer some respite, but the speed of growth of bramble is such that hardly a season will pass before substantial re-growth is achieved and the problem is back. Application of herbicide without first cutting back leads to an inordinate amount of poison being plastered across the environment to cover all the foliage in the thicket. 

The only sustainable way forward is a combination of mechanical and chemical control.

This involves cutting back bramble stems close to the ground and waiting for the first flush of regrowth to appear, which is promptly spot-sprayed with an appropriate systemic herbicide. The active chemical will enter the leaves and be translocated (carried) in the phloem tissue to kill the root system.

COMMON SNOWBERRY (SYMPORICARPOS ALBUS)

Common snowberry is exotic and looks the part. All except one of 15 species in the symphoricarpos genus, including S. albus which is naturalised in the UK, are native to the Pacific North West area of North America covering parts of USA and Canada.

However, those who know their botany will quickly recognise a closely related plant species native to the British Isles. That plant is the honeysuckle (lonicera pericylymenum) because both honeysuckle (woodbine) and snowberry are paid-up members of the plant family caprilfoliaceae. 

Snowberry is naturally found along the banks of rivers and streams in swampy thickets, in forests and on rocky hillsides. This shows snowberry is generally unfussed about light levels or soil type, which makes it the ideal shrub for more difficult planting areas suffering from deep shade and shallow soil. 

Snowberry’s natural versatility can be exploited by landowners who value the dense-growing shrub for a wide range of applications in difficult locations as hedges, for riparian planting to stabilise the riverbank soil stabilisation, preventing soil erosion on hillsides and for land reclamation and game bird cover.

SNOWBERRY BOTANY

Chestnut-brown-coloured stems bear paired, oval-shaped leaves with wavy margins.

Small, pink and white, bell-shaped flowers are borne in clusters while fruits are the white berry-like drupes containing two nutlets (bony endocarp) inside which is the seed.

Indeed like the ‘blackberry’ the ‘snowberry’ is not a botanical berry but a drupe. When the white berries are broken open, the mesocarp inside resembles a fine granular snow.

Snowberry plants will root sucker to form dense thickets while the plant’s vigorous root system is what provides fast anchorage for successful soil stabilisation and erosion control plantings and projects along water courses. This is essentially the same reason why S. alba is such a useful species for hedgerow establishment, especially when hedges within the 2 m high x 2 m wide range are required. 

In this instance, the growing plants will require continual hands-on management so that landowners end up with a well-managed and manicured hedge and not a dense thicket.

Snowberry in early October and bearing a collection of mature and immature fruit, a single flower and with leaves still green and firmly attached to the plant

Selective removal of suckers to open up the shrub is not only important for hedge structure, but crucially important to improve air-circulation to minimise the wide range of fungal diseases afflicting snowberry. Diseases like anthracnose, powdery mildew and rust thrive in the high humidity created by the naturally dense shrub canopy of common snowberry. This can be catered for by planting seedlings further apart than would normally be done for hedgerow species growing to within the 2m high x 2 m wide range.

Snowberry is nominally a deciduous shrub, but hangs onto its leaves well into autumn and winter and will continue to grow during mild spells. In October, snowberry in southern England is still sending up a profusion of leaf-laden new shoots. When the leaves finally drop, tightly knit bunches of white fruit stay on the now bare and frosty shoots – explaining why yet another common name in North America is ‘ice apple’.