They might be small, but tree seeds are fascinating structures that can reveal a lot about the tree they came from.

Take a look at how you can identify seven of the most common UK tree seeds, and find out how their individual features help them disperse far and wide.

Did you know?

Ash trees have no fixed sex and some 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.

1. Ash (Fraxinus excelsior)

Ash seeds are known as 'samaras' or 'keys'. They develop through late summer and autumn, hanging from branches in large bunches until they fall from the tree in winter. Each 'key' is around 5cm long and turns the colour of a brown paper bag when ripe.

Ash seeds have a classic winged structure which helps them catch the breeze and be carried away by the wind.

Did you know?

Studies show a correlation between drought years and mast years, with drought conditions and dry summers being followed by heavy masts.

2. Beech (Fagus sylvatica)

The seeds of beech trees are referred to as 'masts', with particularly seed-heavy years known as mast years. Beech masts are enclosed in tough brown cases covered in prickles, and the seeds themselves are quite flat and triangular, dark brown, and usually around 1.8cm in length. You can usually see them littering the ground between September and November.

Did you know?

Holly trees rely heavily on insects for pollination, which means that in bad pollinator years the seed yield will be low. This then also affects birds like blackbirds and thrushes which feed on the berries in winter.

3. Holly (Ilex aquifolium)

Bright red holly berries are known as 'drupes' and can be seen between November and February each year, making them a popular Christmas symbol.

Each holly berry is a complicated structure. It holds a hard seed in its centre (this is the fruit), then around this lies a fleshy orange layer called the mesocarp, and on top of that, the red outer skin, or exocarp.

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Did you know?

Caterpillars of the white-letter hairstreak butterfly feed on elms. Sadly, this beautiful insect has declined dramatically since Dutch elm disease arrived in the UK, wiping out its larval food source.

4. Wych elm (Ulmus glabra)

Wych elm is a surprisingly early seed-bearer. Its seeds, known as samaras, appear between May and July.

The seeds themselves are unmistakable – contained within a paper-thin, oily, winged case, which turns from green to brown when ripe. As winged seeds, each samara is whisked away by the wind, with spring storms often decimating wych elms of their seeds long before the end of their season in July.

Did you know?

Silver birch is monoecious, meaning both male and female flowers (catkins) are found on the same tree. Each flower looks different, however. Male catkins are long and yellow-brown in colour, while female catkins are smaller, short and bright green.

5. Silver birch (Betula pendula)

Silver birch seeds aren't immediately noticeable as they grow inside the tree's female catkins between August and October. Once they're pollinated, the catkins thicken, change colour from bright green to dark crimson, and disintegrate, allowing the seeds to be borne away by the wind.

Like wych elm, silver birch seeds are known as samaras and are also enclosed in a papery case. They're much smaller, however, and the case is almost translucent.

Did you know?

The case of a small-leaved lime seed is smooth and lacks ridges, which can help you tell it apart from a large-leaved lime or common lime seed.

6. Small-leaved lime (Tilia cordata)

The seeds of small-leaved lime trees look like small brown nuts. They're hard, and usually no more than a few millimetres long.

Small-leaved limes usually fruit in October, when the seeds appear in clusters of between four to 10 round pods attached to a single leaf bracket. This helps them helicopter away in the wind.

Did you know?

The fleshy aril is the only part of the yew that isn't poisonous. It's a favourite autumn food of blackbirds, thrushes, fieldfares and dormice. Birds can't process the toxic seed in their digestive system, so it's dispersed, in-tact, in their droppings.

7. Yew (Taxus baccata)

Yew is a native conifer with a difference – rather than the usual cones produced by species like Scots pine, it has small, red, fleshy fruits called 'arils'.

Yew trees usually fruit between September and October, but not all of them. Separate trees carry male and female flowers, so not all yews will produce seeds.

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