Totnes & District

Report 093 24/10/18

What a wonderful warm, calm day Wednesday 24th October was; a perfect day for an outdoor activity. With kind permission from Lorna Howell, 8 members met in the car park of Lukesland Gardens, Ivybridge at 10.30am. A short walk was made to the seating area at the side of the main house, with Terry gathering a few leaves on the way. Using the leaves, his paint box and a white tile Terry explained the basic principles of Autumn Leaf colour. Chlorophyll, the substance responsible for harnessing the energy from the sun and converting it into stored energy (sugars) is made up of various compounds. Standard chlorophyll absorbs red and blue light waves and reflects green, hiding carotinoides and xanthophylls which reflect orange/red and yellow respectively. They all help in the manufacture of sugars - photosynthesis. The green chlorophyll is more sensitive to low temperatures and breaks down revealing the caratinoides and xanthophylls, both of which may be present in different amounts and therefore produce a range of colours from pale yellow to intense orange. However while still producing sugars and not able to convert them into starch or proteins, the leaves would ‘pickle’ themselves in sugar, but avoid such a problem by converting sugars to Anthocyanins, which produce red, purples and pinks depending on the acidity or alkalinity of the cell sap. Using his paints Terry demonstrated the effect of mixing yellow with purple - browns resulted. Now combine these mixtures of colours with the brown tannins that can be produced as chlorophyll breaks down and waste materials that the plant may deposit in its leaves prior to leaf fall, and the range of colours including browns can be explained.

After the ‘teach in’ we walked around the gardens looking at various leaf shapes and leaf margins,; important diagnostic features of plants. We were also able to see many examples of autumn leaf colour, and where foliage exposed to more sun and low temperatures were colouring better than protected foliage. An autumn of sunny warm days followed by cold but not freezing nights induce the leaves to colour, and they are likely to be good if the plants are not suffering from water shortage, the atmosphere is moist and the plants are protected from winds that would readily blow the leaves away.

Lukesland is a private garden with limited opening days. Fortunately on ‘Open Days’ their tea room is open for drinks, cakes, bread, cheese and pickles and delicious soup,all of which most of us sampled before going home.