Autumn leaves and seeds

Delve a little deeper and you'll discover that autumn leaf litter has so much more than just the usual papery delights in store.

It's autumn, the nights are drawing in, and the wildlife's starting to look a little... haggard. The trees are littering the ground with much more than just leaves and a walk in the park reveals squirrels twitching with excitement as they leap through the leaf litter examining acorns and chomping on chestnuts.

But do you know your sycamore samaras from your ash achenes, your chestnuts from your conkers? Or which leaves turn to mush on landing and which hang around for fidgety wellies to frolic in?

The keys to life

Samaras, whirligigs, spinning jennies, helicopters or keys... whatever you call them, these incredible aeronautical seed-carrying spinners can be seen throughout autumn wherever large deciduous woods are found.

The keys of the field maple are almost straight and can have a pinkish tinge.

Most of us remember playing with these spiralling seeds at one time or another, but did you know that the angle of the key wings can tell tale of the different trees from which they fall?

If you find a key with broad wings which are joined in a straight line it's invariably our native field maple. The wings spin as the seeds fall slowing their descent and allowing winds to blow them far away from the tree. For more information about field maples and help with their ID, download this Field maple sheet from Nature Detectives [PDF].

Montpellier maple keys have wings almost side by side. Image © Matt hunt.

Our native sycamore tree is actually a member of the maple family too. It has keys with wings that are a little longer and thinner, and joined together at around a 120 degree angle.

Other keys you might spot include those of the Norway maple, where the wings will be at a more acute angle, and the less common Montpellier maple, for which the wings are joined at such an acute angle that they are almost side by side.

If you can't tell what sort of spinning seed it is that you've found then look around for the tree it came from and see if you can identify its parent.

Ash tree keys hang in a bundle.

The European ash has distinctive bundles of dangling keys with a singular wing. The wings have a more symmetrical structure than those of sycamore or maple trees and a smoother surface to the touch. With their one wing, ash seeds fall to the ground in more of a twirling motion. Ash seeds will actually hang on the tree late into the winter so you will be most likely to see these still on the tree during autumn.
For more information about ash trees and help with their ID download this Ash sheet from Nature Detectives [PDF].

Lime tree seeds hang off leaf-like bracts.

From a distance the tiny fruit and leaves of the lime tree native to the UK also look like keys. The fruit grow dangling down beneath a yellowish bract which is a specialised leaf that, when released, enables the seed to drift further from the tree.

The non-native large-leaved lime's bracts can be distinguished from those of the native lime as they will have more than two fruit.

Littering leaves

There aren't many better ways of getting your children engaging with autumn nature than a good leaf hunt.

Sycamore leaves are big culprits in problem leaf litter. They turn to mulch almost as soon as they hit the ground and are slow to break down. Birch and ash are also similarly slimy and slippery with brittle twigs making them a big problem for Network Rail in autumns past.

Horse chestnut leaves browned and shrivelled by leaf miner caterpillars.

The railway lines suffer mostly from sycamore, Norway maple, poplar, ash, lime and horse and sweet chestnut leaves as these are the biggest.

Beech trees' oval leaves the lobed leaves of the oak rot more quickly making them good for leaf compost.

Other distinctive leaves in autumn are those of the horsechestnut which can be seen shriveled and brown even in early autumn as they suffer from the presence of leaf miners. These hungry caterpillars aren't thought to cause any lasting damage to the tree but do cause the leaves to curl inwards.

Going nuts

Squirrels and jays will be busy burying nuts in the autumn, caching them for the cold winter when food will be scarce.

Acorns from the English oak have stalks.

Acorns are a classic favourite of squirrels and are easily identifiable by their smooth oval shape and round caps. They tend to be green on the tree and browning by the time they fall. There are two types of oak that are common in the UK: the English oak and the Sessile oak. You can tell them apart by the acorns which are stalked in the English oak and stalkless (sessile) in the sessile oak.

Watch a fabulous clip of an acorn growing from the BBC archive.

Conkers. Image © John Parish.

Another easily recognisable nut is the conker. The fruit of the horse chestnut tree, it is significantly larger than an acorn, smooth and round, and shiny when it first breaks free of its spiky shell. Conkers are reddish brown in colour with a whitish patch on one side and are well-known icons of autumn across Britain.

The traditional British game of conkers has been played for centuries and the World Conker Championships take place in Northamptonshire in mid October so start practising now!
 

Sweet chestnuts have long spiked cases. Image © Elaine123.

Sweet chestnuts are very different to the conkers of the horse chestnut tree on examination as they have much longer and denser spikes on their cases. The cases also have very little flesh compared to the conker.

The nuts themselves are also smaller with slightly downy skin and have a more irregular shape, commonly with one concave and one convex side to them.

Sweet chestnuts are edible to us when ripe but have to be cooked and removed from their husks.
 

Beech nuts some in cases covered in spiny burs.

The common beech tree has nuts much smaller than acorns and chestnuts. They come in pairs inside cases covered in spiny burs. The curled burs catch onto the fur of passing animals allowing the nuts to be distributed far from the parent tree.

Beechnuts are edible to humans but are barely worth the effort as they are so small and need to be removed from their husks individually. You'll easily spot the nut cases around woodland floors and they're especially crunchy under foot, but the nuts themselves are much smaller.

Whatever you're after amongst the leaf litter, the best time to go rummaging is in the early autumn before the squirrels, mice and birds have eaten the lot! If you're out with young children check out Nature Detectives autumn downloads for exciting activities to take with you.