Equisetum palustre |
Equisetum x nelsonii |
|
---|---|---|
marsh horsetail |
Nelson's horsetail |
|
Sheaths | rectangular, 5–10 mm, green; teeth 3–7 mm, persistent with a dark center and pale hyaline margins. |
|
Aerial stems | annual, monomorphic; up to 80 cm tall, deeply grooved, green; ribs 5–10; central cavity less than 33% of the stem diameter. |
|
Branches | in whorls; from the mid-region of the stem, numerous to sparse (rarely absent); ridges 4–6; first internode shorter than the sheath and not exserted. |
|
Cones | pedunculate. |
|
2n | =216. |
|
Equisetum palustre |
Equisetum x nelsonii |
|
Distribution | ||
Discussion | Swamps, marshes. 0–1200 m. Casc, WV. Northern North America; Asia, Europe. Native. Damaged green stems of E. arvense can sometimes produce cones and resemble E. palustre. However, the latter differs from E. arvense in the size of its central cavity (greater than 33% stem diameter vs. less than 33% in E. arvense) and the first branch internode (shorter than sheath vs. longer than sheath in E. arvense). |
[This taxon does not have a floristic treatment in Flora of Oregon.] |
Source | Flora of Oregon, volume 1, page 79 Duncan Thomas |
Flora of Oregon, volume 1 |
Sibling taxa | ||
Web links |
|