Images Dated 25th March 1987

Spore of field horsetail

False colour scanning electron micrograph of spores of the field horsetail, Equisetum arvense. The horsetail is the only living type of a primitive family of plants, the Sphenopsids, that were predominant at the formation of the coal measures. The vegetative stems are produced from underground rhizomes & the leaves are reduced to toothed sheaths at the leaf joints. Fertile shoots bear conelike sporangia, carrying the spores, which in this species appear in Spring. The picture shows a moist spore bound tightly by their elators, or bands of thickened cells. As the spores dry out, the elators unfurl, tossing the spores out of the sporangium. Mag: X 320 at 35mm. Original is BW print b450/029

© DR JEREMY BURGESS/SCIENCEPHOTO LIBRARY