Late Autumn Tree Colours

Late Autumn Tree Colours

Late Autumn Tree Colours – These photos were all taken on November 17th 2021. This year winds have been light and some trees have retained their leaves later than normal and with spectacular colouring. To learn more about why deciduous tree leaves change colour in autumn click HEREClick on any photo to enlarge it.

Wildflowers in July

Wildflowers in July

These wild flowers were photographed in early July  at the northern end of The Chilterns on a short walk to Ivinghoe Beacon – Pyramidal Orchid, Common Spotted orchid, Greater Knapweed, Self Heal, Agrimony, Goatsbeard, Mignonette, Dropwort and Clustered Bellflower. Ivinghoe Beacon is located on The Ridgeway which is an ancient track that runs through the Chilterns, an Area of Outstanding Natural Beauty AONB. The chalk grasslands along this route provide a wonderful habitat for wild flowers which are abundant in July. The flowers shown here are not rare but easy to see and photograph. 

Click on any photo to enlarge it.

pyramidal orchid

Pyramidal Orchid Anacamptis pyramidalis

common spotted orchid

​Common Spotted Orchid Dactylorhiza fuchsii 

agrimony

Agrimony Agrimonia eupatoria

greater knapweed

Greater Knapweed Centaurea scabiosa

goatsbeard  'clock'

Goatsbeard Tragopogon pratensis

self-heal close up

Self-heal Prunella vulgaris

 clustered bellflower

Clustered Bellflower Campanula glomerata 

dropwort

Dropwort Filipendula vulgaris

wild mignonette

Wild Mignonette Reseda lutea

Orchids in June

Orchids in June

Two Orchids in flower in June :- The Greater Butterfly Orchid Platanthera chlorantha is found throughout Britain on grassy slopes and woods. It is fragrant at night and pollinated by night-flying moths. The Fragrant Orchid Gymnadenia conopsea is pollinated by butterflies and moths, attracted by its strong scent. It is found throughout Britain on grassland, especially on chalk or limestone and across northern Europe and western Asia. 

Greater Butterfly Orchid

Greater Butterfly Orchid
Greater Butterfly Orchid spurs

The orchid has a very long (26mm) slightly-curved spur at the back. The plant is up to 60cm tall and has 10 to 30 flowers on a spiked inflorescence. It produces nectar which is stored in the long spur.

Greater Butterfly Orchid labellum

The orchid has a  short (16mm) strap-shaped labellum at the front. This is a close-up of the labellum and its entrance. Pollinia are white initially but turn brown with age as shown here. The  pollinia are located either side of the spur entrance and stick to the large eyes on the side of the moth’s head, not to its proboscis.

Fragrant Orchid

Fragrant Orchid

 The plant is 40 cm tall with a 10cm spike of up to 50 flowers.

Fragrant Orchid spurs

The long (13mm) spurs are shown in this photo. Floral scent emission timing (day or night) may vary depending on the type of pollinator targeted. The orchid’s long spur is partly filled with nectar but only an insect with a long proboscis, such as the Hummingbird Hawk Moth or the Painted Lady can reach it. As the insect tries to reach the nectar, the pollinia are attached to its proboscis. 

Fragrant Orchid labellum

The labellum is 3-lobed with 2 ‘petals’ forming a hood over the column. The pollinia can just be seen in this photo and two stigmatic lobes are on either side of them at the entrance to the spur.

Hazel catkins

Hazel catkins

Hazel Catkins

The Common Hazel is a wind pollinated, monoecious tree.  A perfect flower, like those found on Cherry trees, has male and female parts combined but this can lead to self pollination so  some trees separate the male and female flower parts. If the separated parts are on the same tree it is known as monoecious (Greek for one household). Alder, Oak, Beech, Birch, Hornbeam and Sweet Chestnut are other examples of monoecious trees. 

Hazel catkins – the hazel is a monoecious tree with male flowers on hanging catkins and tiny female bud-like flowers with red stigmas. To see catkins on the closely-related Turkish Hazel click HERE

Hazel male catkin in February

The male flowers are on yellow catkins that hang down ready to release pollen onto the wind. There may be over 200 unisexual male flowers on a single catkin. 

hazel male catkin anthers

Each maleflower is covered by a scale which lifts when the catkin is ready to release pollen. Underneath each scale there are 4 pairs of green stamens full of pollen. The stamens split open to release pollen for wind dispersal when the conditions are suitable.

 

hazel male catkin anthers

Close-up showing the catkin after the pollen has been released and the stamens have turned brown. After pollen release, the male catkin soon drops off.

hazel female catkin

The  female flowers resemble a bud, with crimson stigmas that protrude when they are ready to receive pollen. The flower buds are located on the branch above the catkin, to avoid self-pollination.

hazel female catkin close-up

The female flower bud is shown in close-up in this photo. Each bud has several flowers. Each flower has 4 stigmas to collect pollen. If fertilised, each flower will produce  one nut, known as a cob.

hazel nuts or cobs

 One to four nuts are produced from one bud, depending on how many flowers were fertilised.

Autumn Leaf Colours

Autumn Leaf Colours

Autumn Leaf Colours

Autumn leaf colours can be used to identify trees in Britain – some trees have leaves that turn yellow, others red and some stay green until they fall.The most striking thing about deciduous trees in autumn is not that they shed their leaves, it’s the fact that the leaves on some trees change their colour before they fall. Why does this happen – the leaves have been green all spring and summer? Why don’t the green leaves just drop off without changing colour and why on some trees do the leaves turn yellow and on others red. In fact most trees in Britain, for example Common Alder and Common Ash, shed green or brown leaves but about a third of all species turn either yellow or red. 

In Britain our landscape consists of trees that originated in Europe, America, Asia and Australia. Most trees of European origin turn yellow with hardly any turning red. European tree species that turn yellow include the Norway Maple, Field Maple, Aspen, Silver Birch, Common Beech (yellow then brown), Common Hornbeam, Willows, Poplars and Limes.  The Ginkgo  introduced from China, has yellow autumn leaves. In America there are some native trees  such as the Quaking Aspen, Tulip Tree, some Oaks, some Maples and some Hickories that are yellow in autumn but many more that turn red.  Here are 8 examples of trees that turn yellow.

Not all conifers are evergreens. Some are deciduous and shed their leaves in autumn. Examples are the Swamp Cypress and the Dawn Redwood. For information on these trees click HERE

 

norway maple tree in autumn

Norway Maple 

aspen trees in autumn

Aspen

Lombardy poplars in autumn

Lombardy Poplar

ginkgo tree leaves in autumn

Ginkgo

Hornbeam

Broad-leaved Lime

Silver Birch

Field Maple

Nearly all the trees that turn red in autumn in Britain  were introduced from North America or Asia. Examples are the Red Maple, Sugar Maple, Red Oak, Scarlet Oak, Pin Oak and Sweet Gum from North America and  Japanese Maple varieties such as ‘Ozakasuki’, Sargent’s Cherry, Persian Ironwood, Snowy Mespil and Pillar Apple from Asia. A few European trees, such as the Wild Service Tree and the Bird Cherry turn orange/red and some, such as the Norway Maple and the Common Rowan, may turn orange/red under stressed conditions. Some varieties of European trees with red autumn leaves include the Sycamore ‘brilliantissimum’ and the Claret Ash ‘Raywood’. Here are 8 examples of trees that turn red in autumn.

sweet gum tree in autumn

Sweet Gum is native to south-eastern USA and Central America. It was introduced to Britain in1681 

claret ash tree in autumn

Claret Ash ‘Raywood’ is a variety of the Caucasian Ash and was introduce to Britain in the 1920s 

japanese maple 'ozakasuki' leaf in autumn

Japanese Maple ‘Ozakasuki’ is a variety of Acer palmatum

persian ironwood leaves in autumn

Persian Ironwood. Introduced from Iran in 1841

red maple leaf in autumn
Red  Maple Acer rubrum is the most common tree in North America.
acer saccharum sugar maple leaf

Sugar Maple Acer Saccharum is one of the main sources of maple syrup in Canada

Sargent's Cherry Prunus sargentii leaves

Sargent’s Cherry Prunus sargentii was introduced to Britain from Northern Asia in 1890

Red Oak Quercus rubra leaf
Red Oak Quercus rubra. Goes bright red in North America but is this colour in Britain. One of  most common oak species in North America. Introduced to Britain in 1724

Two main theories

A leaf is the main photosynthetic organ of a tree. This is a process in which carbon dioxide from the air is combined with water in the presence of light to produce sugars and oxygen. The molecule that carries this out is called chlorophyll. It absorbs red and blue wavelengths of light and reflects green so that the leaf appears green to us. It is a complex molecule with a ring of nitrogen at its centre surrounding an atom of magnesium. Shorter days and lower temperatures trigger leaf fall but this is a multi-step controlled shutdown process. Some trees just discard green leaves but in other trees  the chlorophyll and proteins in the leaf are broken down and essential nutrients, such as nitrogen, are re-adsorbed and stored in the shoots and roots until spring. 

As the chlorophyll breaks down, the leaf loses its green colour and other pigments can be seen. Carotenoids are yellow and orange and are already present. Anthocyanins, which give the leaf a red colour, are newly made. Carotenoids are needed to keep the cells going during the re-absorption stage so most trees that change colour have yellow leaves in autumn but 14% have red leaves. Why, then do some trees go to the expense of making Anthocyanins before the leaves fall? There are two main theories.

Photoprotection hypothesis

Anthocyanins protect the leaf from light damage during the period of re-absorption. This is the basis for the photoprotection hypothesis – it extends the leaf life during shut-down and enables it to send more nutrients back to the tree before the leaf drops. If this is true, trees with yellow leaves should drop their leaves earlier.

Co-evolution hypothesis

Alternatively the red coloration may be a signal to parasites, such as aphids, that have a strong preference for green leaves, to not lay their eggs on red leaves in autumn. This avoids future damage and is the basis for the co-evolution hypothesis. Red colour may be correlated with the level of herbivore defence in the tree, and therefore plants investing more in defences show more autumn colours. If insects adapt to avoid red leaves in autumn, this will lead to a co-evolutionary process in which both preference for green in aphids and intensity (or duration) of red in trees increase.

Flowers and Fruit in August

Flowers and Fruit in August

Flowers and Fruit in August

In August  garden flowers are abundant with many coming into flower in late July or early August. Few wildflowers come out in August but grasslands are full of Knapweeds, Wild Carrot, Teasel, Scabious, Harebells, Ragwort, Thistles and Hawkweeds.  Fruit is ripening on some trees and shrubs. Here are photos of 7 garden flowers and 3 fruits seen in early August.

rudbeckia flower

This is a variety of Rudbekia fulgida.  Rudbeckia may be annuals, biennials or perennials. They are native to North America.  The common name is Black-eyed Susan

anemone japonica flower

Japanese Anemone ‘Queen Charlotte’ . This hybrid was developed from the species Anemone hupehensis,  native to China.

Michaelmas daisy flower

A Michaelmas Daisy hybrid. This is similar to the European wildflower  Aster amellus named after the Archangel Michael, whose  feast day is September 29.

globe thistle  flower

The Globe Thistle flower heads, like all thistles, are made up entirely of disc florets. Native to Eurasia, it was introduced to Britain in the 16th century as a garden plant.

hibiscus flower

A Hibiscus hybrid based on the  species Hibiscus syriacus which is native to China.

gladiolus flower

A Gladiolus variety. Gladioli originate mainly in South Africa, which has approximately 250 of the 300 known species. 

phlox flower

Phlox ‘Mount Fuji’ is a popular garden plant. The Phlox family of 25 genera and 250 species is found mainly in North America with one genus Polemonium found in Europe and two in Asia. 

black mulberry fruit

Black Mulberry. The fruit turns red and is sweet and juicy at the end of July. This type of fruit is known as a multiple fruit because it consists of a number of drupes fused together to make one big fruit.

 

blackberry fruit

Bramble fruit, shown here, is black when ripe. Raspberry fruit  is red when ripe. Where the fruit  connects to its stem is  the receptacle. It  is fleshy and comes away when the Blackberry is picked but does not come away when the Raspberry is picked.

elderberry fruit

The fruit of the Elder  is used to make wine and has many medicinal uses, but the seeds and other plant parts are toxic.