Hypericum canadense

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Hypericum canadense
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Malpighiales
Family: Hypericaceae
Genus: Hypericum
Section:
H. sect. Trigynobrathys
Species:
H. canadense
Binomial name
Hypericum canadense

Hypericum canadense, known as Canadian St. Johns-wort,

The Netherlands.[5] The specific epithet
canadense means "Canadian".

Description

Hypericum canadense is a perennial herb that grows in short basal offshoots that are produced in autumn. The slender stems reach 5–75 cm in height and are simple or branched in their upper half. The stems are four-angled and slightly winged. The roots are fibrous and the herb lacks any

internodes
. The leaves are one to three nerved with secondary veins weaker except near the leaf base.

The flowers are solitary or arranged in simple

capsule is red or purplish, measuring 4–6.5 mm long and 2-2.5 mm wide.[6] The capsule has persistent styles measuring about 0.5 mm long. The light brown and cylindrical seeds have conical or rounded ends, measuring 0.6 mm long.[7]
The herb flowers and fruits from late July to early September.

It has a

diploid number
of 16.

  • Flower
    Flower
  • Green Lake County, Wisconsin
    Green Lake County, Wisconsin

Hybrids and varieties

In Nova Scotia, assumed hybrids between H. canadense and Hypericum mutilum subsp. boreale have occurred. These hybrids can be recognized as Hypericum × dissimulatum as they match material described by Eugene P. Bicknell from Nantucket.[7]

One variety, H. canadense var. magninsulare, differs in petal shape. Its petals are ovate or ovate-lanceolate and taper to an acute or obtuse apex. The reflexed petals are a pale yellow tinged with red towards their apex, with clear nerves. In typical H. canadense, the petals have a rounded or subtruncate apex, reflex only towards the end of flowering, lack any red tinge, and have exceedingly obscure nerves. Besides the petals, the variety has the same habit as the typical form. The variety is clearly more than a distinct color form, as some specimens, for example from

Grand Manan, the island where the variety was first distinguished and is primarily distributed.[8]

Distribution

It occurs naturally in eastern parts of Canada and the United States, from

extirpated from Manitoba.[9]

H. canadense was discovered in Europe as early as 1935 near Almelo in the Netherlands, with previously collected specimens in 1909 determined to be H. canadense as well. The herb was reputed to have been discovered in 1959 in France but has since been shown to be erroneous, the specimens collected being H. majus. H. majus was found in Germany in 1956 and in both France and Germany the herb was likely introduced by American troops. H. canadense was first discovered in Ireland in 1954, with a single plant being found on the shore of Lough Mask. In 1968, the plant was discovered in Ireland again, this time 200 km (120 mi) south of Lough Mask in Glengarriff.[10] The Irish plant is more similar to H. canadense var. magninsulare than to the type, given the red line on its petals and its intermediate petal shape, between the narrow, pointed shape of the variety and the lanceolate, rounded shape of the type.[11]

There are three possibilities for the presence of H. canadense in Europe. First, the plant could be introduced by human means. This is highly improbable, with it being unlikely that any European gardener would cultivate the plant and unlikely that any American troops could transport the plant, though that American hypothesis has been supposed. Second, the plant could have been transported to Ireland by natural means, most likely being carried on the feet of the

glaciation. Najas flexilis is similar in hardiness and survived the last glaciation as fossil evidence shows. The attempted creation of the Corrib-Mask Canal lowered water levels in the herb's Irish area, and if the plant was underwater before then, the relict hypothesis would be disproven. An 1841 map shows that the distribution of H. canadense stops short of the lakeshore by 90–300 yd (82–274 m). However, the plant clearly occurs below an older shore line of uncertain age; the shore line is certainly post-glacial, but it may be old enough for the plant to migrate down to its current occurrence. The abundance and conspicuousness of the plant opposes this theory, as in the 1950s a few plants were discovered simultaneously in France and Ireland, but more recently the plants are quite abundant, suggesting more recent naturalization of the herb. The majority of evidence is in favor of the relict hypothesis, but future spreading or lack thereof of the plant will better suggest recent introduction or the growth of an autochthon.[11][12]

Habitat

Hypericum canadense occurs in wet or dry soils in sandy ditches and clearings, road verges, pastures, boggy or peaty regions, gravelly beaches, and occasionally in woodlands. It is considered a

facultative wetland plant in the United States, meaning that it usually occurs in wetlands, but may also occur in non-wetlands, typically in areas where the soil surface is flooded at least seasonally.[13][14]

In

watertable sand flats" and acidic wet to wet-mesic sand prairies.[16]

The variety H. canadense var. magninsulare prefers wet soils in pastures or swamps.[8] In Ireland, the herb occurs in wet soils of pH between 4 and 5, with rich organic matter. The plant requires base-poor and peaty soils to occur in Ireland. Grazing by cattle likely reduces competition and provides open ground for establishment of the herb.[10]

Hypericum canadense and

Maritimes towards Lake Superior. H. majus is rare in the Maritimes but occurs as far west as British Columbia. In the Maritimes H. canadense is restricted to mostly Paleozoic formations and in Ontario it prefers Precambrian formations. H. majus occurs in a broader range of habitats.[7]

References

  1. ^ "Hypericum canadense L." ipni.org. International Plant Names Index. Retrieved 2018-09-23.
  2. ^ Reznicek, A. A.; Voss, E. G.; Walters, B. S., eds. (February 2011). "Hypericum canadense". Michigan Flora Online. University of Michigan Herbarium.
  3. ^ "Hypericum canadense". Go Botany. New England Wildflower Society. Retrieved 2018-09-23.
  4. ^ a b USDA, NRCS (n.d.). "Hypericum canadense". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 2018-09-23.
  5. ^ Robson, Norman K. B. "Hypericum canadense". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). New York and Oxford: Oxford University Press. Retrieved 2018-09-23 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  6. ISBN 978-0-442-22250-5
    .
  7. ^ a b c Gillett, John Montague; Robson, Norman Keith Bonner (1981). "The St. John's-worts of Canada (Guttiferae)". The St. John's-worts of Canada (Guttiferae) (11): 21–23.
  8. ^ a b Weatherby, Charles Alfred (1928). "A VARIETY OF HYPERICUM CANADENSE". Rhodora. 30: 188–190.
  9. ^ "Hypericum canadense Linnaeus". data.canadensys.net. Database of Vascular Plants of Canada (VASCAN). Retrieved 4 December 2018.
  10. ^ a b Webb, D. A.; Halliday, G. (1973). "The distribution, habitat and status of Hypericum canadense L. in Ireland" (PDF). Watsonia. 9: 333–344.
  11. ^ a b Webb, David Allardice (1958). "Hypericum canadense L. in western Ireland" (PDF). Citeseer. {{cite journal}}: Cite journal requires |journal= (help)
  12. doi:10.1111/j.1438-8677.1959.tb00016.x
    .
  13. ^ Lichvar, R.W., D.L. Banks, W.N. Kirchner, and N.C. Melvin. 2016. The National Wetland Plant List: 2016 wetland ratings. Phytoneuron 2016-30: 1-17. Published 28 April 2016. ISSN 2153-733X
  14. ^ Lichvar R.W. N.C. Melvin M.L. Butterwick and W.N. Kirchner. National Wetland Plant List Indicator Rating Definitions. ERDC/CRREL TR-12-1. U.S. Army Engineer Research and Development Center Cold Regions Research and Engineering Laboratory Hanover NH.
  15. ^ Nathaniel Lord Britton, Addison Brown (1913). An Illustrated Flora of the Northern United States, Canada and the British Possessions: From Newfoundland to the Parallel of the Southern Boundary of Virginia, and from the Atlantic Ocean Westward to the 102d Meridian. Vol. 2 (2 ed.). Charles Scribner's Sons. p. 536.
  16. ^ Wilhelm, Gerould; Rericha, Laura (2017). Flora of the Chicago Region: A Floristic and Ecological Synthesis. Indiana Academy of Sciences.
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