Equisetum sylvaticum, the wood horsetail, is a horsetail (family Equisetaceae) native to the Northern Hemisphere, occurring in North America and Eurasia. Because of its lacy appearance, it is considered among the most attractive of the horsetails.
Description
This perennial pteridophyte has erect, hollow stems that grow from in length and from 1–4 mm thick.
The branches themselves are compound and delicate, occurring in whorls and drooping downward. There are generally 12 or more branches per whorl. Fertile stems are at first tan-to-brown and unbranched, but later become like the sterile stems, which are more highly branched and green. All the stems have 10–18 spiny vertical ridges that contain silica spicules. The leaves are scales fused into sheaths that cover the stems and branches. These spiny leaves are larger and looser on the fertile stems. The plant is well identifiable from the 3–6 reddish brown leaf sheaths or "teeth".
The fertile stems are shorter than the others; on these develop the cones that bear the spore casings or strobili.
Reproduction
This plant reproduces by spores, but its primary means of reproduction is done vegetatively by rhizomes. These rhizome systems are deep and extensive, as well as extremely long-lived. These creeping rhizomes occasionally produce tubers, and often outweigh the above-ground growth by 100 to 1.