Equisetum palustre |
Equisetum ×ferrissii |
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marsh horsetail, prêle des marais |
Ferris' horsetail, Ferriss' horsetail, Ferriss' scouring-rush |
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Sheaths | elongate, 4–9 × 2–5 mm; teeth dark, 5–10, narrow, 2–5 mm, margins white, scarious. |
elongate, 7–17 × 3–12 mm, becoming dark-girdled with age; teeth 14–32, articulate and promptly shed or persistent. |
Aerial stems | monomorphic, green, branched or unbranched, 20–80 cm; hollow center small, to 1/3 stem diam.; vallecular canals nearly as large. |
having basal part persisting over winter, unbranched, 20–180 cm; lines of stomates single; ridges 14–32. |
Branches | when present only from midstem nodes, spreading, hollow; ridges 4–6; valleys rounded; 1st internode of each branch shorter than subtending stem sheath; sheath teeth narrow. |
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Cone | apex pointed; spores white, misshapen. |
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2n | =216. |
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Equisetum palustre |
Equisetum ×ferrissii |
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Phenology | Cones maturing in summer. | Cones maturing in late spring–early summer but spores not shed. |
Habitat | Marshes and swamps | Moist lakeshores, riverbanks, roadsides, prairies |
Elevation | 0–1500m (0–4900ft) | 0–2500 m (0–8200 ft) |
Distribution |
AK; CA; ID; ME; MI; MN; MT; ND; NH; NY; OR; PA; VT; WA; WI; AB; BC; MB; NB; NF; NS; NT; ON; PE; QC; SK; YT; Eurasia s to Himalayas; n China; Korea; Japan
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AR; AZ; CA; CO; CT; DC; DE; IA; ID; IL; IN; KS; MA; MD; ME; MI; MN; MO; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SD; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; ON; QC; SK; n Mexico including Baja California
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Discussion | The name Equisetum palustre var. americanum has been used for specimens from the flora that have longer teeth than those from Eurasia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The hybrid between Equisetum hyemale and E. laevigatum, E. × ferrissii, was mistaken for E. laevigatum by Schaffner and some subsequent authors. Although sterile, it exists outside the range of E. laevigatum, and apparently it is dispersed vegetatively (R.L. Hauke 1963). Perhaps it has persisted in some areas from a time when the parents were both there. Equisetum × ferrissii has been reported from Maine, New Hampshire, Rhode Island, South Dakota, and Vermont, but I have not seen specimens from those states. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 2. | FNA vol. 2. |
Parent taxa | Equisetaceae > Equisetum > subg. Hippochaete | Equisetaceae > Equisetum > subg. Equisetum |
Sibling taxa | ||
Synonyms | E. palustre var. americanum | E. hyemale var. elatum, E. hyemale var. intermedium |
Name authority | Linnaeus: Sp. Pl. 2: 1061. (1753) | Clute: Fern Bull. 12: 22. (1904) |
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