Grasses are flowering plants; they have all the same bits and pieces as a buttercup or a dandelion. The difference is that they are wind pollinated so they have not adapted their structure to meet the needs of insect pollinators; they have no scent, no nectaries, no colours or ultra-violet sign posts and no petals to make landing platforms.
Grasses raise their flower heads above their leaves so that the wind will catch them. Their stamens are held away from the flower, and the anthers, which contain the pollen, are attached in such a way that the slightest movement or breath of air sets them jiggling.
In this enlargement of DKG’s fascinating 2019 macro-image of meadow foxtail (Alopecurus pratensis) , the anthers are the pale yellow, banana-looking structures; they are containers for the pollen. When they are ripe, they split along their length and the tiny pollen grains spill out and are carried away in the air currents. The empty anthers have shrivelled and changed colour.
The stigmas, the female parts of the plant, are the feather-like structures behind the stamens. Below, in an even closer magnification, you can see the pollen grains sticking to the stigmas. To prevent self fertilisation, meadow foxtail’s stigmas ripen before its anthers, so these pollen grains will have come from a different plant.
If you look closely, there are two very small invertebrates in this picture; one, at the top, appears to have wings, the second which is orange and lower down appears to be wingless.
On each stigma, one of the pollen grains will produce a pollen tube that will grow down through the stigma’s stem (called the style) to the ovary where it will fertilise the egg cell. The ovaries are hidden behind the dark-edged, triangular, green bracts, and each one will produce a single seed.
Find a magnifying glass, lie down in the reserve’s fields and take a good look at the many grasses before they are cut for this year’s hay; they are fascinating plants.
All the pictures are by DKG, taken in 2019
Leave a Reply