White-flowering trees that signpost spring – Act 1: Early Spring

SPRING in Britain is a poorly defined and demarcated event. Two official start dates are 1st March (the beginning of the traditionally recognised three-month spring period) and 21st March (spring or vernal equinox), but for me, spring is a sequential period starting early in the New Year and from then on signposted by a sequence of white flowering trees.

As January advances, everything is perceptibly brighter, with days becoming lighter and longer. This is the start of the laboured progression from winter into early spring, and a time of anticipation, with the ‘threat’ of spring as exciting as the season itself.

The start and sequence of spring is clearly subjective, but the blossoming of our common and mostly native white-flowering trees gives as good a guide as any. The benefit of using these as sentinels of spring is their generally ubiquitous occurrence and easy accessibility to rural dwellers and ‘townies’ alike. Most will grow and flower anywhere and everywhere, from parks and gardens to waste ground and railway embankments.

Their exact flowering time varies from year to year depending on weather conditions and local anomalies. Dates and times referred to in this article are based on casual observations made in London and the Home Counties over the last 50 years.

Despite being the first wild Prunus species to flower, the blossom and foliage of cherry plum show at the same time.

FIRST WHITE WEDDING OF THE YEAR

British springs are essentially white affairs, with white blossom on trees, white flowers on the ground and white clouds in the sky.

“Spring goeth all in white,

Crowned with milk-white may,

In fleecy flocks of light,

O’er heaven the white clouds stray.”

April, 1885 by Robert Bridges (1844–1930)

Most British native trees bearing white flowers belong to the family Rosaceae. And, together with a 500-year-old introduction called cherry plum (also in the Rosaceae) and common elder, there are sufficient white-flowered species blooming in sequence to define and demarcate a typical British spring.

The first white blossom to venture out in the woodland is the cherry plum or myrobalan plum (Prunus cerasifera), a 16th-century introduction from western Asia, now naturalised in hedgerows, scrub and woodland, especially in southern England. On cold, crisp days in February, when little else is moving, the delicate white flowers of the cherry plum (larger but more thinly spread than those on later-flowering blackthorn) appear clean and washday white against clear blue skies.

The appearance of the snow-white flowers on P. cerasifera traditionally coincides with the first white flowers (snowdrops – Galanthus nivalis) on the woodland floor. Pure white snowdrops are closely associated with Candlemas, the ancient pagan festival of light on 2nd February, the same date as Groundhog Day in the USA, similarly used as a marker for the progress of spring.

Prunus cerasifera is at home in thickets and neglected hedgerows and, when seen from a distance, brings early light relief to the dull, brown background of other woodland trees and shrubs, which are still in winter condition. Cherry plum is at its best whenever February has long periods of high pressure to give crisp, cold days with blue skies. Cherry plum shows remarkable resilience to night frosts, but this first white wedding of the year is rapidly blown to bits by strong south-westerly winds and driving rain, even if the temperature is much higher. The flowering period may extend over several weeks when calm and cold conditions prevail to leave the blossom almost stranded in time.

Confusion with blackthorn is common, with some texts failing to acknowledge the existence of cherry plum and erroneously claiming blackthorn blossoms in February. There is much genetic variation within the population, probably due to hybridisation between cherry plum and native blackthorn (Prunus spinosa), as well as other closely related Prunus introductions, mostly from Asia. In southern England there will be white blossom at the woodland margin, in the hedgerow, in parkland and on waste ground from late January through to mid-April, depending on the year, with pure-line cherry plum at the start and pure-line blackthorn at the end.

Two ornamental cherry plums with red leaves and pink flowers are popular for roadside planting in the suburbs. These are: P. cerasifera ‘Pissardi’, discovered by one Monsieur Pissard, French gardener to the Shah of Persia, who sent the tree to France in 1886; and P. cerasifera ‘Nigra’, with its darker red leaves and rose-pink flowers. The trees often sucker and, if poorly managed, end up pink-blossomed surrounded by a white-blossomed shrub, growing from the wild-type rootstock. Suburban streets built from the 1930s onwards are still lined with mature cherry plum trees offering an early display of pink spring blossom, followed by dense red foliage throughout spring and summer. The dense canopy of branches, twigs and leaves has become an increasingly popular early-spring nesting site for birds like pigeons, ringed doves and the magpie following its relatively recent adaptation to the urban environment.  

Blackthorn forms huge thickets in high, uncut hedges and bursts into bloom during April.

BLACKTHORN IN BLOOM

Next in line to flower is the true native P. spinosa (blackthorn or sloe), often confused with P. cerasifera. Prunus spinosa is intensely thorny compared to the occasional spines of P. cerasifera and bears smaller flowers on shorter pedicels (3 mm), later in appearance and considerably more crowded on the stems. Blackthorn blossom is pure white, borne on dark-coloured branches, giving the shrub its name. The blossom is profligate year after year and seemingly unaffected by previous late summer/early autumn conditions when the flower bud initials are formed (so much that the lichen-encrusted branches are almost completely hidden by dense clusters of white flowers).

Blackthorn rarely flowers with enthusiasm earlier than the end of March, but once in bloom it is more intense, albeit shorter-lived than cherry plum blossom, especially during warm spells. By the same token, it is much less resistant to late frosts, which reduce fine displays of blossom to a mass of brown, withered flowers literally overnight. 

The essential difference between pure-line P. cerasifera and P. spinosa is that the distinctly toothed leaves of the former emerge at the same time as the flowers, whereas flowering in blackthorn will be done and dusted by the time the leaves emerge in the second half of April. There is a huge range of Prunus hybrids in the environment offering intermediate displays related to flower shape, size and timing, as well as density of thorns and appearance of leaves in relation to the time of flowering.

Blackthorn will sucker freely and, if left to its own devices, forms huge thickets to provide stunning displays of white blossom for a week or two in early April. Strong north-east winds in late March and early April regularly coincide with the appearance of blackthorn blossom, settled like snow along the black branches. Country folk traditionally call this last spell of really cold weather the ‘Blackthorn winter’.

“While yet we wait for spring, and from the dry

And blackening east that so embitters March,

Well-housed must watch grey fields and meadows parch,

And driven dust and withering snowflake fly.”

Growth of Love by Robert Bridges (1844–1930)

Early April is boom-time for blackthorn and butterflies like the peacock, which will have just come out of winter hibernation to find blackthorn blossom a readily available food source. They will also nectar on flowers of the less well-known wild plums, including damson and bullace.

Lone native wild pear tree by the roadside in North Yorkshire, perhaps a remnant of an ancient hedgerow (picture courtesy of Dr Roderick Robinson).

The final event which wraps up this first act of spring is the wild pear tree bursting into bloom in the first half of April. Increasingly rare in their true wild form, pear trees can still be found in almost every location from hedgerows to railway embankments, but many are adulterated with genes from domestic pears. That said, the canopy of a large pear tree in full bloom, on a sunny, early April day, whether truly wild or ‘mule’, is a sight that takes some beating. True wild pear trees can usually be distinguished by a preponderance of wicked-looking thorns. Wild pear in bloom tells me that spring has really arrived, with no turning back.

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