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Clayton's sweetroot. Image by Jennifer Anderson, hosted by the USDA-NRCS PLANTS Database.


SPECIES: Osmorhiza claytonii
AUTHORSHIP AND CITATION: Pavek, Diane S. 1992. Osmorhiza claytonii. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: []. Revisions: On 1 June 2018, the common name of this species was changed in FEIS from: sweet cicely to: Clayton's sweetroot. Images were also added. ABBREVIATION: OSMCLA SYNONYMS: Osmorhiza aristata var. brevistylis (DC.) Bowin Washingtonia claytonii (Michx.) Britt. NRCS PLANT CODE: OSCL COMMON NAMES: Clayton's sweetroot downy sweet cicely sweet cicely sweet jarvil wooly sweet cicely TAXONOMY: The scientific name of Clayton's sweetroot is Osmorhiza claytonii (Michx.) C. B., Clarke in the parsley family (Apiaceae). There are no recognized subspecies, varieties, or forms. LIFE FORM: Forb FEDERAL LEGAL STATUS: No special status OTHER STATUS: NO-ENTRY


SPECIES: Osmorhiza claytonii
GENERAL DISTRIBUTION: In Canada, Clayton's sweetroot is found from southern Manitoba east to Quebec and south to Newfoundland [11,14,15,21,31]. In the United States, Clayton's sweetroot is distributed from the New England states west to the Great Plains, extending south into central Arkansas and northern Alabama [3,14,20,29,32].
Distribution of Clayton's sweetroot. Map courtesy of USDA, NRCS. 2018. The PLANTS Database. National Plant Data Team, Greensboro, NC [2018, January 29] [33].
   FRES14  Oak - pine
   FRES15  Oak - hickory
   FRES17  Elm - ash - cottonwood
   FRES18  Maple - beech - birch

     AL  AR  CT  GA  KS  KY  IN  IA  IL  ME
     MD  MA  MI  MN  MO  NE  NH  NJ  NC  ND
     NY  OH  PA  RI  SC  SD  TN  VT  VA  WI
     WV  MB  NB  NF  NS  ON  PE  PQ  SK

   14  Great Plains

   K098  Northern floodplain forest
   K099  Maple - basswood forest
   K100  Oak - hickory forest
   K101  Elm - ash forest
   K102  Beech - maple forest
   K103  Mixed mesophytic forest
   K104  Appalachian oak forest
   K106  Northern hardwoods
   K111  Oak - hickory - pine forest

    16  Aspen
    17  Pin cherry
    18  Paper birch
    19  Gray birch - red maple
    24  Hemlock - yellow birch
    25  Sugar maple - beech - yellow birch
    26  Sugar maple - basswood
    27  Sugar maple
    28  Black cherry - maple
    39  Black ash - American elm - red maple
    42  Bur oak
    46  Eastern redcedar
    52  White oak - black oak - northern red oak
    53  White oak
    55  Northern red oak
    57  Yellow-poplar
    59  Yellow-poplar - white oak - northern red oak
    60  Beech - sugar maple
    63  Cottonwood
    93  Sugarberry - American elm - green ash
    95  Black willow
   108  Red maple
   109  Hawthorn
   110  Black oak


Clayton's sweetroot has a patchy distribution throughout the understory of the
northern hardwood and eastern deciduous forests [17].  It is an
indicator and/or a dominant species in the sugar maple (Acer saccharum)
climax communities of the northern states and Canada [6,8,17,37].
Common codominants in these climax communities with sugar maple are
American beech (Fagus grandifolia), red oak (Quercus rubra), and eastern
hemlock (Tsuga canadensis) [8,17].  Clayton's sweetroot is an indicator of
highly productive sites of climax sugar maple-basswood (Tilia americana)
stands and subclimax oak-aspen (Quercus spp.-Populus tremuloides)
[9,16].  In a Minnesota sugar maple-basswood climax forest, frequency
was six Clayton's sweetroot plants per square yard (7.3 plants/sq m) [9].

Clayton's sweetroot is a minor component in the sugar maple-white ash (Fraxinus
americana) forest zone and in the sugar maple associations with yellow
birch (Betula alleghaniensis), black ash (Fraxinus nigra), or American
elm (Ulmus americana) of eastern Canada [22,24].

Forest classifications that list Clayton's sweetroot as an indicator or
dominant species are:

(1)  Field guide:  Habitat classification system for the Upper Peninsula of
     Michigan and Northeast Wisconsin [6]
(2)  The principal plant associations of the Saint Lawrence Valley [8]
(3)  The "big woods" of Minnesota: its structure, and relation to
     climate, fire, and soils [9]
(4)  Variation in overstory biomass among glacial landforms and
     ecological land units in northwestern lower Michigan [16]
(5)  Field guide to forest habitat types of northern Wisconsin [17]
(6)  Soil-vegetation relationships in northern hardwoods of Quebec [22]
(7)  A forest classification for the maritime provinces [24]
(8)  The composition and dynamics of a beech-maple climax community [37].


SPECIES: Osmorhiza claytonii
IMPORTANCE TO LIVESTOCK AND WILDLIFE: No information was available on this topic. PALATABILITY: No information was available on this topic. NUTRITIONAL VALUE: No information was available on this topic. COVER VALUE: No information was available on this topic. VALUE FOR REHABILITATION OF DISTURBED SITES: No information was available on this topic. OTHER USES AND VALUES: No information was available on this topic. OTHER MANAGEMENT CONSIDERATIONS: No information was available on this topic.


SPECIES: Osmorhiza claytonii
GENERAL BOTANICAL CHARACTERISTICS: Clayton's sweetroot is a native perennial forb with thickened fibrous roots extending from a caudex [11]. Its solitary stem grows from 12 to 35 inches (30-90 cm) high with compound leaves [6,36]. Flower stalks have very small umbels, producing thin black seeds with stiffly hairy ribs [3]. RAUNKIAER LIFE FORM: Hemicryptophyte REGENERATION PROCESSES: New foliage in the fall and annual flower stalks in the spring are generated from a root stock [6,17]. In mature forests that typically have long-term disturbance regimes, Clayton's sweetroot responds to small scale disturbances, such as one causing a tree gap, by increasing its cover [7,35]. Clayton's sweetroot seeds are disseminated by dropping from the plant or by snagging in animal fur, hair, or clothing [6,17]. Clayton's sweetroot seeds require warm stratification followed by cold stratification before germination will occur [3]. In laboratory studies, 98 percent of the seeds germinated after 4 weeks with day temperatures at 86 degrees Fahrenheit (30 deg C) and night temperatures at 59 degrees Fahrenheit (15 deg C) followed by 2 weeks at 41 degrees Fahrenheit (5 deg C) days and nights [3]. Under field conditions, Clayton's sweetroot sheds seed during the summer or early autumn when temperatures are relatively warm to hot, which results in high germination rates the following spring. Baskin and Baskin [3] also found that a portion of the seed did not germinate until the second spring after shedding. Clayton's sweetroot forms a short-lived seed bank. Seeds that are not dropped and remain attached to the plant during the winter have longer dormancy after being shed. This seed required 12 weeks warm stratification followed by cold stratification to yield 96 percent germination [3]. SITE CHARACTERISTICS: Clayton's sweetroot grows in rich, mesic, mixed-hardwood forests [3,29]. It is common in woods on shaded hillsides [11,15,32,34]. It also occurs on the forested edges of wet prairies and meadows [5,18]. Sites on which Clayton's sweetroot occurs vary from well-drained gravelly or sandy loams to poorly drained clay loams [2,24,26]. Occasionally, there is a top layer of humus, 1 to 4 inches (2.5-10 cm) deep [37]. Water may be at or near the soil surface for most of the year [5,16,18]. The soil pH is acidic to strongly acidic; calcium and magnesium have generally been leached out [18]. Clayton's sweetroot is found on level to very steep (75 percent) slopes [18,24]. It occurs from elevations of 600 feet to 2,200 feet (183-670 m) [27,28]. The climate is generally characterized by short, mild summers and long, cold winters [18,27]. At one representative site, average annual precipitation is about 39 inches (1,000 mm); snowpack, an average of 10 inches (250 cm) per year, may last from November to April [27]. The growing season is approximately 200 days over its range [37]. Associated overstory species are bur oak (Quercus macrocarpa), yellow-poplar (Liriodendron tulipifera), and black willow (Salix nigra) [5,35]. Common associated shrubs are fly honeysuckle (Lonicera canadensis), red elderberry (Sambucus pubens), and juneberry (Amelanchier alnifolia) [5,28]. Herbaceous associates are enchanter's nightshade (Circaea quadrisulcata), American pokeweed (Phytolacca americana), feather Solomon's-seal (Smilacina racemosa), and several violet species (Viola spp.) [26,27,28]. SUCCESSIONAL STATUS: Clayton's sweetroot is relatively shade tolerant [1,37]. It is a mature, approximate climax or climax understory species in deciduous forests [2,28]. In studies of Ohio old field-deciduous forest seres, Clayton's sweetroot was present herb only in 200+ year-old stands as a subdominant or minor herb [2,28,35]. SEASONAL DEVELOPMENT: In the spring before the canopy closes, Clayton's sweetroot initiates foliage growth and then puts up a flower stalk. It begins flowering in April in the southern part of its range [29,32]. In the northern parts, it flowers progressively later: blooming in May and June in the central states, and June to August in the far north [14,15,21,29]. Clayton's sweetroot seeds mature from June through August. The seeds are shed primarily in late autumn and winter; however, they may not be dropped until the following spring [3]. Seedlings generally emerge in the spring [3]. The flower stalk dies in the fall, but new leaves are put out at that time [6,17]. Clayton's sweetroot overwinters as a rosette [9].


SPECIES: Osmorhiza claytonii
FIRE ECOLOGY OR ADAPTATIONS: In the communities in which Clayton's sweetroot grows, fire occurrence ranges from uncommon in the northern hardwoods to very common in the Appalachian oak forests [23]. A covering of soil protects the caudex of an established Clayton's sweetroot plant. Under moist conditions, a root stock may survive fire. Seed buried in soil may be insulated enough to survive [13]. However, seeds attached to stalks at the time of burning will die. Accumulated dead stalks are a fire hazard to Clayton's sweetroot. Aerial stems of Clayton's sweetroot die each fall and generally remain attached [6,17]. These old stems make the plant more susceptible to burning. FIRE REGIMES: Find fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes". POSTFIRE REGENERATION STRATEGY: Caudex, growing points in soil Secondary colonizer - off-site seed


SPECIES: Osmorhiza claytonii
IMMEDIATE FIRE EFFECT ON PLANT: No fire studies have been done on Clayton's sweetroot. Fire top-kills foliage. The soil-covered root stock may survive, unless conditions are dry and duff layers are well-developed [37]. Under these conditions, fire may consume the caudex and kill the plant and seed bank. PLANT RESPONSE TO FIRE: Fire severity and rooting depth of the caudex control recovery of Clayton's sweetroot. If burned in late summer or early autumn, surviving root stocks should sprout, since Clayton's sweetroot normally initiates new leaves in the fall [6,17]. With a persistent seed bank, Clayton's sweetroot seeds may germinate in the first postfire spring [3]. Off-site regeneration is possible; seeds can be transported into burned areas. DISCUSSION AND QUALIFICATION OF PLANT RESPONSE: The Research Project Summary Effects of surface fires in a mixed red and eastern white pine stand in Michigan provides information on prescribed fire and postfire response of plant community species, including Clayton's sweetroot, that was not available when this species review was written. FIRE MANAGEMENT CONSIDERATIONS: No information was available on this topic.


SPECIES: Osmorhiza claytonii
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Urbana, IL: University of Illinois Press. 593 p. [18964] 21. Lakela, O. 1965. A flora of northeastern Minnesota. Minneapolis, MN: University of Minnesota Press. 541 p. [18142] 22. Lemieux, G. J. 1963. Soil-vegetation relationships in northern hardwoods of Quebec. In: Forest-soil relationships in North America. Corvallis, OR: Oregon State University Press: 163-176. [8874] 23. Lotan, James E.; Alexander, Martin E.; Arno, Stephen F.; [and others]. 1981. Effects of fire on flora: A state-of-knowledge review. National fire effects workshop; 1978 April 10-14; Denver, CO. Gen. Tech. Rep. WO-16. Washington, DC: U.S. Department of Agriculture, Forest Service. 71 p. [1475] 24. Loucks, O. L. 1959. A forest classification for the Maritime Provinces. Proceedings, Nova Scotian Institute on Science. 25: 86-167. [15408] 25. Lyon, L. Jack; Stickney, Peter F. 1976. Early vegetal succession following large northern Rocky Mountain wildfires. In: Proceedings, Tall Timbers fire ecology conference and Intermountain Fire Research Council fire and land management symposium; 1974 October 8-10; Missoula, MT. No. 14. Tallahassee, FL: Tall Timbers Research Station: 355-373. [1496] 26. McEwen, Douglas; Schneider, Gary. 1976. Herbaceous productivity and species composition associated with harvest intensities in a southern Michigan mixed hardwood forest. In: Fralish, James S.; Weaver, George T.; Schlesinger, Richard C., eds. Central hardwood forest conference: Proceedings of a meeting; 1976 October 17-19; Carbondale, IL. Carbondale, IL: Southern Illinois University: 409-429. [3815] 27. Mladenoff, David J. 1990. The relationship of the soil seed bank and understory vegetation in old-growth northern hardwood-hemlock treefall gaps. Canadian Journal of Botany. 68: 2714-2721. [13477] 28. Potter, Loren D.; Moir, D. Ross. 1961. Phytosociological study of burned deciduous woods, Turtle Mountains North Dakota. Ecology. 42(3): 468-480. [10191] 29. Radford, Albert E.; Ahles, Harry E.; Bell, C. Ritchie. 1968. Manual of the vascular flora of the Carolinas. Chapel Hill, NC: The University of North Carolina Press. 1183 p. [7606] 30. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843] 31. Scoggan, H. J. 1978. The flora of Canada. Ottawa, Canada: National Museums of Canada. (4 volumes). [18143] 32. Steyermark, J. A. 1963. Flora of Missouri. Ames, IA: Iowa State University Press. 1725 p. [18144] 33. USDA Natural Resources Conservation Service. 2018. PLANTS Database, [Online]. U.S. Department of Agriculture, Natural Resources Conservation Service (Producer). Available: [34262] 34. Van Bruggen, T. 1976. The vascular plants of South Dakota. Ames, IA: Iowa State University Press. 538 p. [19200] 35. Vankat, John L.; Carson, Walter P. 1991. Floristics of a chronosequence corresponding to old field-deciduous forest succession in sw Ohio. III. Post-disturbance vegetation. Bulletin of the Torrey Botanical Club. 118(4): 385-391. [17754] 36. Voss, Edward G. 1985. Michigan flora. Part II. Dicots (Saururaceae--Cornaceae). Bull. 59. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 724 p. [11472] 37. Williams, Arthur B. 1936. The composition and dynamics of a beech-maple climax community. Ecological Monographs. 6(3): 318-408. [8346] 38. Stickney, Peter F. 1989. Seral origin of species originating in northern Rocky Mountain forests. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT; RWU 4403 files. 7 p. [20090]

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