Four Urban Poplars

Four Urban Poplars

Four Urban Poplars with all images and text taken from the book Field Guide to the Trees of Britain and Europe published by Reed New Holland in 2017, author Alan Birkett and ISBN 9781921517839

Male Aspen catkins
Grey Poplar male catkin


 Poplars have male catkins that release pollen in late March and early April. They open before the leaves so are easy to see. The first photo shows the male catkins of an Aspen. This is a Poplar that tolerates cold conditions. It is a smaller tree than most Poplars. It is a species that grows in cool regions across the whole of Europe and west Asia. (The American Aspen is a different species). It is more likely to be found in the north and west of Britain and is common in the Scottish Highlands. It is typically found in oak or birch woodland. It can spread by sending suckers up from its roots. Male and female flowers are on separate trees.  The second photo shows the male catkin of a Grey Poplar. This is a natural hybrid between the White Poplar and the Aspen. It may have been introduced. It has a wide distribution in Europe and Western Asia. It is common throughout Britain. It is easily confused with the White Poplar but it grows faster and becomes a larger tree. Because the tree is a hybrid it may show aspects of both parents.

Balck Poplar male catkins
Hybrid Black Poplar male catkins

The first photo shows the male catkins of a Black Poplar. This is a large tree, native to Northwest Europe, including England and Wales where it is usually found as the variety ‘betulifolia’. It is endangered. It is common in the Vale of Aylesbury and in Manchester but rare elsewhere. This odd distribution is probably the result of local planting for timber. The tree is generally found growing close to water and nearly always leans. The bark is distinctive. Old trees have deep cracks that swirl round the trunk. Most of the trees are male and bear colourful catkins in spring. In 2002 there were estimated to be 7000 trees in the whole of the UK with only 600 females. This was probably an underestimate so there may be as many as 15,000 trees left in the UK but a disease known as “Scab” is attacking the ones growing near Manchester.

The second photo shows the catkins of a Hybrid Black Poplar. These hybrids arise when the European Black Poplar is crossed with the American Eastern Cottonwood. Some hybrids are natural but many are artificial. Hybrid Black Poplars are common. Some have been planted for timber production but others have been planted in large numbers in new towns and developments because they grow rapidly. They are generally known by their ‘cultivated variety’ name such as ‘Robusta’, ‘Regenerata’, ‘Serotina’, ‘Eugenei’ etc.

Early Flowering Tree

Early Flowering Tree

The Cherry Plum is a thorny shrub or small tree and is frequently planted in urban areas because it is one of the first trees to come into flower in the spring. It is also known as the Myrobalan Plum. It is native to a region from the Balkans to central Asia and has been cultivated in Britain from the 16th century. The word “Myrobalan” was originally used for the sharp-tasting fruit of an Asian tree before it was applied to this plum. 

Its white flowers come out before the leaves in early March. It is often confused with the Blackthorn, which has almost identical flowers. The flower of the Cherry Plum is bigger than that of the Blackthorn but apart from that they are very similar. However, the Plum is the earliest to flower (usually in March) and the blackthorn flowers four  weeks later in April. To learn more about a comparison between Cherry Plum, Blackthorn and Wild Cherry flowers click HERE


Tree in August

The fruit in July. The plum is yellow or red and can be eaten raw or used in cooking.

There is a cultivar of the Cherry Plum called Prunus cerasifera ‘Nigra’ which looks similar and flowers at the same time but has  pink flowers and purple leaves.

Ash flowers in March

Ash flowers in March

Ash flowers in March

The Common Ash Fraxinus excelsior produces flowers in March before the leaves. Ash trees have a complex reproductive system. The flowers have no petals and may be male, female or bisexual. In any population some trees have only male flowers and produce pollen, some only female flowers and produce seeds and some have  bisexual flowers  and produce pollen and seeds.

Common Ash tree male flowers

The  photo shows male flowers in March, before the leaves. Ash flowers have no petals. This photo of a male flower cluster shows the purple anthers that split open to release pollen onto the wind.

Common Ash tree male/female flowers

The  photo shows flowers that have male and female parts. It shows the female styles and stigmas sticking up above the male anthers. When (male) pollen falls on the (female) stigmas, fertilisation takes place and fruit formation begins. Stigmas on the flower are not receptive to pollen when it is being released by the same flower. This avoids self-fertilisation.

Comon Ash tree female flowers

The photo shows fertilised female flowers in April. The purple fruits are just starting to form and the leaves are just coming out.

Common Ash tree fruit

The  photo shows how the Ash fruits, known as keys, hang down in bunches in July. Each fruit is technically called a samara. The word refers to any dry fruit which has flattened wings attached to it to help in its wind dispersion.