Leaf Colour and Light Reflection

LEAF COLOUR: Different chlorophyll pigments in different grasses give each a characteristic hue. In particular, if we use perennial ryegrass as our reference (we will call this colour "emerald" green), we will find that some grasses are more yellow and some grasses are more blue in their leaf colour. The human eye can learn to recognise these colour differences, often when several metres away from the plant in question.


Emerald green
(e.g. Perennial ryegrass)

Yellow green
(e.g. kikuyu)

Blue green
(e.g. phalaris)

However, note that colour differences are not infallible identification criteria, because nutrient or drought stresses also result in colour change. With practice, stress induced colour change can be distinguished from species pigmentation, even so.


LIGHT REFLECTION: Not only do leaves of different plants have different colour hues, but they also reflect light differently because of differences in cuticle structure and composition. In particular, some plants are notable for their shiny leaf surface (below left), while others have dull leaves (below, right).


MORE ON COLOUR: Stem bases of pasture plants may also show distinctive colours. These include shades of purple (Yorkshire fog - purple veins), red (perennial ryegrass - red stem base), yellow-brown (crested dogstail - where green stem colour fades to cream), and chocolate brown (dead leaves of fine fescue and perennial ryegrass) - examples below, but do not try to memorise these just yet, you will meet them again later.


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