Equisetum sylvaticum, wood horsetail
Matthews, Robin F. 1993. Equisetum sylvaticum, wood horsetail. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/equsyl
| Abbreviation | Common Name | Scientific Name | Classification | Status |
|---|---|---|---|---|
| Plants | ||||
| EQUSYL | wood horsetail | Equisetum sylvaticum | Life Form: Plants/Fern or Fern Ally, Plants/Forb Kingdom: Plantae Class: Horsetail Order: Equisetales Family: Equisetaceae Genus: Equisetum | Fed. Protected: No Nativity: Native Invasiveness: Noninvasive |
Taxonomy
The currently accepted scientific name of wood horsetail is Equisetum sylvaticum L. [5,14,22,33]. The following varieties and form are recognized [7,14,33,36]:
- Equisetum sylvaticum var. sylvaticum—with scabrous branches
- E. sylvaticum var. pauciramosum Milde.—smooth branches, slightly branched
- E. sylvaticum f. multiramosum Fern.—smooth branches, copiously branched
Wood horsetail is a highly variable species; many varieties and forms have been described that have little taxonomic significance [5].
Wood horsetail apparently hybridizes with meadow horsetail (E. pratense) [10].
Synonyms
- No entry
Other Common Names
woodland horsetail, sylvan horsetail
General Distribution
Wood horsetail is a circumboreal species [18,19,21,28]. In North America it is distributed throughout Alaska and Canada south to the Pacific Northwest, the Great Lakes states, New England, and North Carolina [5,14,33,36].
States and Provinces
- United States: AK CT DE ID IL IN IA KY ME MD MA MI MN MT NH NJ NY NC ND OH OR PA RI SD TN VT VA WA WV WI WY
- Canada: AB BC MB NB NF NT NS ON PE PQ SK YT
Site Characteristics
Wood horsetail most commonly occurs in cool, moist, shaded to somewhat open forests [5,18,21,39]. It also occurs on streambanks, and in bogs, swamps, and forest openings [5,25,30,33]. Wood horsetail is an indicator of boreal and cool-temperate climates, and very moist to wet, nitrogen-poor soils [25]. Soils may be poorly drained to moderately well drained [6,27]. Wood horsetail is found from lowlands to subalpine regions [22]. In the Adirondack Mountains of New York, it occurs from 1,460 to 2,200 feet (438-660 m) in elevation [27]. Gametophytes of wood horsetail are found on substrates with a lower pH than are gametophytes of other horesetail species [10].
Plant Communities
Wood horsetail is most prevalent in lowland wet conifer forests but is also common in mixed upland, dry conifer, and deciduous forest habitats [3]. In addition, it is found in meadows, bogs, swamps, and along streambanks [5,19,34,46].
The following publications classify wood horsetail as a dominant herbaceous layer component:
- Field guide to forest ecosystems of west-central Alberta [6]
- Classification, description, and dynamics of plant communities after fire in the taiga of interior Alaska [15]
- The Alaska vegetation classification [44]
Species commonly associated with wood horsetail in jack pine (Pinus banksiana), white spruce (Picea glauca), or black spruce (P. mariana) habitats include alder (Alnus spp.), willows (Salix spp.), highbush cranberry (Viburnum edule), bunchberry (Cornus canadensis), bog Labrador tea (Ledum groenlandicum), twinflower (Linnaea borealis), blueberry (Vaccinium spp.), red raspberry (Rubus idaeus), gooseberry (Ribes spp.), honeysuckle (Lonicera involucrata), leatherleaf (Chamaedaphne calyculata), prickly rose (Rosa acicularis), wild lily-of-the-valley (Maianthemum canadense), naked miterwort (Mitella nuda), coltsfoot (Petasites spp.), common yarrow (Achillea millefolium), fireweed (Epilobium angustifolium), bluejoint reedgrass (Calamagrostis canadensis), sedges (Carex spp.), fire moss (Ceratodon purpurea), feathermosses (Hylocomium splendens, Pleurozium schreberi), and sphagnum mosses (Sphagnum spp.) [1,4,6,11,29].
Botanical Description
Wood horsetail is a perennial, deciduous, homosporous pteridophyte [1,9]. Sterile stems are green with lacy branches and grow up to 28 inches (70 cm) tall. Fertile stems are at first unbranched and lack chlorophyll but become branched and green after spores are released. Strobili are usually 1 inch (3 cm) long and are borne on short stalks at the apices of fertile stems [5,18,39]. The spores germinate to produce a distinct gametophytic generation. The unisexual gametophyte is very small, generally from 0.002 to 0.008 inch (0.5-2.0 mm) in height [9]. Wood horsetail often forms large stands [24]. It has extensive creeping rhizomes which may outweigh aerial shoots by a ratio of 100 to 1 [1].
Raunkiaer Life Form (Raunkiaer 1934)
- Geophyte
Seasonal Development
In the Northern Clay Belt Region, Ontario, fertile shoots of wood horsetail appear before sterile shoots, liberate their spores, and die before sterile shoots complete their growth. Most fertile shoots die by the end of June, and sterile shoots begin to die in August [1]. In most areas within its distributional range, wood horsetail spores are shed from April through May [5,9,18].
Regeneration Processes
Wood horsetail primarily reproduces by vegetative means; the majority of shoots arise from rhizomes [1,12]. Rhizome systems are extensive, deeply buried, and extremely long-lived (perhaps several thousand years old) [1].
The establishment of gametophytes and subsequent sexual reproduction is rare in the wild due to an extremely narrow habitat tolerance. The most critical factor for sexual reproduction appears to be the initial establishment of spores. Gametophytes only establish on recently exposed bare mud, such as around reservoirs or streambanks following flooding. Wood horsetail has a very limited spore dispersal period, and spores are short-lived. Male gametophytes grow at a much slower rate than females. There is also evidence of early male mortality. Gametophytes reach sexual maturity at 3 to 5 weeks and then produce a constant supply of gametes until death. The sex ratio of a population is determined by environmental conditions; female gametophytes are more likely to be produced under favorable conditions [9]. The frequent occurrence of Equisetum hybrids suggests, however, that sexual reproduction is a common occurrence in this genus [10].
Successional Status
Facultative Seral Species
Wood horsetail is shade tolerant [25]. It is found throughout all successional stages to climax forests [45]. Wood horsetail colonizes newly exposed mud on streambanks and floodplains [9], and it invades recently burned areas [25]. In floodplain succession in interior Alaska, wood horsetail is common in 200-year-old white spruce-black spruce and climax black spruce/sphagnum forests [41]. It is also widespread in black spruce stands from 26 to 120 years old in Ontario [38]. Wood horsetail is common in stable, mature forests in west-central Alberta [6].
Immediate Fire Effects
Aboveground stems of wood horsetail are killed by fire [1]. Rhizomes are resistant to fire because they are buried deep in mineral soil [12,45].
Hamilton's Research Papers (Hamilton 2006a, Hamilton 2006b) provide information on prescribed fire and postfire response of many plant species, including wood horsetail, that was not available when this species review was originally written.
Postfire Regeneration Strategy (Stickney 1989)
- Rhizomatous herb, rhizome in soil
- Geophyte, growing points deep in soil
- Ground residual colonizer (on-site, initial community)
- Initial-offsite colonizer (off-site, initial community)
Fire Adaptations
Wood horsetail survives repeated fires by means of deeply buried rhizomes that are apparently almost indestructible [1]. The extensive rhizome system penetrates well into mineral soil or clay, allowing revegetation even after severe fire [1,12,45]. Wood horsetail may be the most abundant herb species after fires in black spruce stands in Alaska. It sprouts after fire in any stage of succession [45].
Plant Response to Fire
In the Northern Clay Belt Region of Ontario, wood horsetail recovers rapidly after fire and is one of the most prominent postfire species. It becomes less abundant in the later stages of postfire succession, but is still present under mature spruce (Picea spp.) stands up to 240 years old. Shoots that appear immediately after fire are sterile, but up to 20 percent of the stems that appear in postfire year 1 are fertile [1].
In central Saskatchewan, wood horsetail was present 4 years after fires on moist and moderately moist sites in jack pine clearcuts [4].
Wood horsetail regenerates rapidly following fire in black spruce/feathermoss forests in southeastern Newfoundland, and its abundance may exceed prefire levels. Its frequency was 27.8 percent in unburned areas and 21.1 percent in areas that had been burned 5 years previously [16].
On mesic black spruce sites in interior Alaska, wood horsetail is present throughout all stages of postfire succession. The following cover and frequency percentages were reported [15]:
| Stage | Years since fire | Cover (%) | Frequency (%) |
|---|---|---|---|
| Newly burned | 0-1 | <0.5 | 10.0 |
| Moss-herb | 1/5 | 4.0 | 65.0 |
| Tall shrub-sapling | 5-30 | 2.0 | 13.0 |
| Dense tree | 30-55 | <0.5 | 11.0 |
| Mixed hardwood-spruce | 56-90 | <0.5 | 5.0 |
| Spruce | 90-200+ | 4.0 | 49.0 |
After the 1971 Wickersham Dome Fire near Fairbanks Alaska, wood horsetail had the following cover and frequency percentages in lightly burned and severely burned black spruce stands (control plot cover and frequency were 1.25 and 60.0 percent, respectively) [43]:
| Severity | 1971 Cover (%) | 1971 Frequency (%) | 1972 Cover (%) | 1972 Frequency (%) | 1973 Cover (%) | 1973 Frequency (%) | 1974 Cover (%) | 1974 Frequency (%) |
|---|---|---|---|---|---|---|---|---|
| Low | 0.1 | 10.0 | 2.65 | 95.0 | 2.6 | 95.0 | 5.7 | 85.0 |
| High | 0 | 0 | 3.35 | 80.0 | 3.6 | 80.0 | 8.95 | 90.0 |
In this same study area, wood horsetail had cover values on fireline sites of 4, 40, and 12 percent in 1972, 1975, and 1980, respectively [42].
Fire Regimes
For fire regime information, search FEIS for this species by entering the species name or acronym on the home page and selecting “Fire Regime” as the publication type.
Fire Management Considerations
No entry.
Federal Status
None
Other Status
Wood horsetail is included on Virginia's rare and endangered vascular plants list [31]. It is listed as threatened in Ohio by the Natural Heritage Program [47].
Importance to Wildlife and Livestock
In interior Alaska, horsetails (Equisetum spp.) comprise the largest component of the spring diet of black bears. Horsetails and blueberries (Vaccinium spp.) are the two most important plant genera to black bears in the region [20].
Palatability and Nutritional Value
Dry matter nutrient content values of wood horsetail collected in the Wallace-Aikens Lake area, Manitoba, were: 6.7 percent crude protein, 1.36 percent calcium, and 0.09 percent phosphorus. Dry matter digestibility was 27.9 percent [35].
Cover Value
No entry.
Value for Rehabilitation or Restoration of Disturbed Sites
No entry.
Other Uses
No entry.
Other Management Considerations
Wood horsetail is poisonous to humans [8].
Table A1— Forest and range ecosystems, Bureau of Land Management (BLM) physiographic regions, Kuchler plant associations, Society for American Foresters (SAF) forest cover types, and Society for Rangeland Management (SRM) rangeland cover types in which this species occurs.
Forest and Range Ecosystems (Garrison et al. 1977)
- FRES10 White - red - jack pine
- FRES11 Spruce - fir
- FRES17 Elm - ash - cottonwood
- FRES18 Maple - beech - birch
- FRES19 Aspen - birch
- FRES20 Douglas-fir
- FRES22 Western white pine
- FRES23 Fir - spruce
- FRES24 Hemlock - Sitka spruce
- FRES25 Larch
- FRES26 Lodgepole pine
- FRES28 Western hardwoods
- FRES37 Mountain meadows
BLM Physiographic Regions (Bernard and Brown 1977)
- 1 Northern Pacific Border
- 2 Cascade Mountains
- 8 Northern Rocky Mountains
- 9 Middle Rocky Mountains
- 15 Black Hills Uplift
Kuchler Plant Associations (Kuchler 1964)
- K001 Spruce - cedar - hemlock forest
- K002 Cedar - hemlock - Douglas-fir forest
- K003 Silver fir - Douglas-fir forest
- K004 Fir - hemlock forest
- K008 Lodgepole pine - subalpine forest
- K012 Douglas-fir forest
- K013 Cedar - hemlock - pine forest
- K014 Grand fir - Douglas-fir forest
- K015 Western spruce - fir forest
- K025 Alder - ash forest
- K093 Great Lakes spruce - fir forest
- K094 Conifer bog
- K095 Great Lakes pine forest
- K096 Northeastern spruce - fir forest
- K097 Southeastern spruce - fir forest
- K098 Northern floodplain forest
- K099 Maple - basswood forest
- K101 Elm - ash forest
- K102 Beech - maple forest
- K103 Mixed mesophytic forest
- K106 Northern hardwoods
- K107 Northern hardwoods - fir forest
- K108 Northern hardwoods - spruce forest
SAF Cover Types (Eyre 1980)
- 1 Jack pine
- 5 Balsam fir
- 12 Black spruce
- 13 Black spruce - tamarack
- 15 Red pine
- 16 Aspen
- 17 Pin cherry
- 18 Paper birch
- 20 White pine - northern red oak - red maple
- 21 Eastern white pine
- 22 White pine - hemlock
- 23 Eastern hemlock
- 24 Hemlock - yellow birch
- 25 Sugar maple - beech - yellow birch
- 26 Sugar maple - basswood
- 27 Sugar maple
- 28 Black cherry - maple
- 30 Red spruce - yellow birch
- 31 Red spruce - sugar maple - beech
- 32 Red spruce
- 33 Red spruce - balsam fir
- 35 Paper birch - red spruce - balsam fir
- 37 Northern white-cedar
- 38 Tamarack
- 39 Black ash - American elm - red maple
- 60 Beech - sugar maple
- 63 Cottonwood
- 107 White spruce
- 108 Red maple
- 201 White spruce
- 202 White spruce - paper birch
- 203 Balsam poplar
- 204 Black spruce
- 205 Mountain hemlock
- 206 Engelmann spruce - subalpine fir
- 210 Interior Douglas-fir
- 212 Western larch
- 213 Grand fir
- 215 Western white pine
- 217 Aspen
- 218 Lodgepole pine
- 221 Red alder
- 222 Black cottonwood - willow
- 223 Sitka spruce
- 224 Western hemlock
- 225 Western hemlock - Sitka spruce
- 226 Coastal true fir - hemlock
- 227 Western redcedar - western hemlock
- 228 Western redcedar
- 229 Pacific Douglas-fir
- 230 Douglas-fir - western hemlock
- 235 Cottonwood - willow
- 251 White spruce - aspen
- 252 Paper birch
- 253 Black spruce - white spruce
- 254 Black spruce - paper birch
SRM Rangeland Cover Types (Shiflet 1994)
- No entry
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