The plant that once towered above the dinosaurs

By Jess Carey

Dinosaurs once roamed through forests of giant horsetails, large bamboo-like plants up to 100 feet tall. Today’s horsetails may seem tall to an insect. Plants in the genus Equisetum are the sole living representatives of their ancient lineage that towered over dinosaurs in the Jurassic age. Today, they grow in dense clusters in wet areas, as a microcosm of their former glory. A bank of Equisetum looks like a tiny forest. Every spring, long tapering green stalks poke through the understory, arising from underground roots specialized for hibernation through winter. Our local species, Equisetum telmateia, is in abundance in wet places on campus and around the Arcata Community Forest. A particularly robust community of horsetails thrive along the creek that runs by the College Creek soccer field. 

Equisetum’s ancient origin is reflected in its alien appearance. Bottlebrushy leaves spiral from green stalks, broken up into nodes that progressively get smaller as the plant grows higher. Fertile, leafless stalks are a lighter brown-green and culminate with a corncob-looking reproductive structure called the strobilus. The strobilus is basically similar to a pinecone, except this plant makes single-celled spores instead of seeds. This reproductive strategy is similar to how fungi reproduce. If you pop off a node and rub it in your fingers, you’ll notice a coarse texture, thanks to silica deposited in the plant’s cell walls. This brittle texture is the origin of the plant’s other common name, scouring rush, as the plant can be used to scour dishes clean.