Tree seed identification: seven common UK tree seeds

A seed tells you a lot about its origins, even before reading its genetic information. The shapes and sizes of seeds vary between species, as does the capsule used to enclose the seed during the development and dispersal stages. This blog explores seven common seeds and how to recognise them.

Ash keys (Photo: Ben Lee)
Ash keys (Photo: Ben Lee)

Ash seeds

Like all seeds, are produced from the female gametes, found within the flower. However, just because an ash tree produced seeds one year does not mean it will seed the next. Common ash trees have no fixed sex and some trees can change sex yearly. Others are hermaphrodites with branches of the opposite sex interspersed throughout the tree. This makes it hard to predict which trees will set seed in a particular year.

Ash has winged seeds known as samaras. This is a common structure used by seeds reliant on wind for dispersal. The seeds hang as clusters in bunches known as keys. They are around 5 cm long and turn a brown paper bag colour when ripe. The seeds can be seen on ash trees for most of the year as they have a good retention rate. Each year’s seeds are out between September and November.

Beech mast (Photo: Ann Tomlin)
Beech mast (Photo: Ann Tomlin)

Beech

All beech trees are capable of producing seeds as the trees produce both male and female flowers. The trees will have mast years, where an abundance of seeds is produced. This is induced by climatic factors, and observations have shown that drought years are often accompanied or followed by heavy mast years.

The seeds of a beech tree are distinctive and referred to as beech masts. They come in small prickly brown cases. The nuts take on a rather flat triangular appearance with a dark brown colouring and are 1.8cm in length. The seeds are present between September and November.

Holly (Photo: Keith Huggett)
Holly (Photo: Keith Huggett)

Holly

Holly has separate male and female bushes and relies on insects to pollinate it in late spring. Therefore if it is a bad pollinator year there will be a low seed yield. The seeds are encased in a crimson berry and are toxic. The seeds are seen between November and February.

Seeds are mainly abundant in autumn but can be found almost year round.

What seeds can you find in your local wood?

Wych elm seeds (Photo: Louise Taylor)
Wych elm seeds (Photo: Louise Taylor)

Wych elm

This has a distinctive paper thin oily green seed, which turns brown when ripe. It is another seed that is dispersed by wind. The wych elm is one of the early seed bearing trees and you will find it in seeds between May and July. However, any spring storms with high winds can take the seeds away long before July.

Silver birch catkins (Photo:  Brian Legg)
Silver birch catkins (Photo: Brian Legg)

Silver birch

This is another tree that has samaras, which are much smaller than those of the elm. The seeds are a lot smaller again in size than the paper thin wings. They are produced in catkins in large numbers between August and October.

Small-leaved lime seeds (Photo: Didier Descouens)
Small-leaved lime seeds (Photo: Didier Descouens)

Small-leaved lime

This comes into seed in October. The seeds are in little round pods that are found in clusters of four to 10. The seed cover is smooth and can be identified by the lack of ridges, as opposed to large-leaved lime and common lime. The seeds are attached to a leaf bracket which helps the seed to helicopter away in the wind.

Yew seed (Photo: Joe Gray)
Yew seed (Photo: Joe Gray)

Yew

Yew is a native conifer with a difference. When you think of conifer seeds you think of cones. Well, with yew you would be wrong; the seeds form in a structure known as an aril. In the case of the yew, the aril is the red fleshy cup that sits around the seed. It is the only part of the yew that is not poisonous to cattle and wildlife. The yew trees have kept a primitive conifer feature and have separate trees for male and female flowers, so not all yew trees will produce seeds. The yew seeds between September and October.

The UK National Tree Seeds Project is working to ensure we do not lose any of the native tree species through collecting and storing seeds from semi natural woodlands in the UK. This work is generously funded through players of the People's Postcode Lottery.

Seeds are mainly abundant in autumn but can be found almost year round.

What seeds can you find in your local wood?