Equisetum horsetail spores (Equisetum arvense) Science Image

Ref: 500029



Equisetum horsetail spores (Equisetum arvense). Light micrograph of common horsetail spores. The spore bears elaters that expand and contract with changes in humidity. Elaters help to tangle spores together into a clump called a propagule and to dig spores into the soil. Horsetails are the only living group of a primitive family of plants, the Sphenopsids, that date back to the Devonian period, 355-410 million years ago. Magnification x174 at 10cm wide.