plants

Relatively few pigment types exist in plants despite the numerous colours we see in them. Some colours, for example white is produced in a physical way without pigments. Plants are composed of cells. The inside of the cell is called the vacuole and contains the sap. This is enclosed by a membrane and surrounded by a layer of protoplasm which contains plastids and the nucleus. The cell wall, usually cellulose divides one cell from another. The pigments that give plants their colour reside in one of three places. Anthoxanthins and anthocyanins which provide a great variety of colours are dissolved in the cell sap in the vacuoles. Chlorophylls (green) and cartenoids (orange, red or brown) are soluble in oil and are often found in oil droplets in the cell or the plastids. The third group are found in the cell walls, often colouring them black, brown, yellow, red, blue or violet.

GREEN	The most common colour, green is present in 0.01mm diameter convex lens shaped plastids in the leaves, stems fruits and seedsof plants. Leaf colour is modified by surface texture, hairyness or gloss
BROWN	Brown pigments are usually located in cell walls when they are damaged and the chemicals oxidise. A bruised apple or autumn leaves are typical. Brown colours in healthy flowers are the result of pigments, eg red and green chlorophyll lying beside each other.
YELLOW	The primrose is coloured with anthoxanthin yellow dissolved in the cell sap. Others may be coloured by carotenoid plastid pigments. When chlorophyll breaks down is produces yellow carotenoid pigments to give the yellow autumn leaves of plants like the Ginko.
ORANGE	Tomato and carrot contain carotenoids. An orange skin though has large cells containing a bright yellow oil, other cells have red sap and there is a yellow waxy coating.
RED	Red in roses, geraniums and autumn leavescomes from anthocyanin pigments in the cell sap. Rose hips and very red tomatoes contain red plastid pigments.
BLUE	Blue in plants is usually due to anthocyanins.