Butterflies flew into November as autumn arrived later this year.

Was that as a result of temperatures throughout October being the highest since 1659 when records began? Perhaps other factors were at work such as the high water table or further evidence of global warming.

Whatever the reasons, leaves certainly appeared reluctant to fall and fewer than usual strong winds helped, allowing us to enjoy the glory of autumn tints for longer.

There is a natural sequence of events whereby the first tree to show signs of yellowing foliage, often as early as August, is the horse chestnut with leaves resembling the large webbed feet of coots.

Following in turn are rowan, beech and lime, then the magnificent maples and finally our native oaks, which retain their leaves tenaciously until December or even later.

One of my favourites is the beautiful red oak, having large spiked leaves that radiate dappled hues of crimson, yellow and green, a testimony to the reason for its introduction from America many years ago.

As autumn approaches, photosynthesis, which keeps foliage green as long as light and warmth of summer prevails, begins to decline as the leaves, having manufactured energy-rich sugars throughout, are not required during winter when the tree rests.

Complex chemical reactions take place to create the autumnal glow which is more vibrant in temperate zones, especially after cool, wet summers and sun-drenched autumns.

Recent research suggests the deep red hues we love so much maybe nature's way of acting as warning signals to aphids to look elsewhere for egg-laying sites.

Two local butterflies however, the white-letter and purple hair-streaks, lay eggs on twigs of wych-elm and oaks, close to next year's already forming leaf buds waiting to open and begin the annual cycle of springtime growth and autumnal decline.

By TONY DRAKEFORD

November 23, 2001 11:31