Hypericum mutilum

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Hypericum mutilum
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. mutilum
Binomial name
Hypericum mutilum
Synonyms[1]
  • Sarothra mutila (L.)
    Y.Kimura

Hypericum mutilum is a species of

diploid number
of 16, and H. mutilum subsp. boreale can have a diploid number of 18.

Taxonomy

Hypericum mutilum is most closely related to Hypericum gymnanthum, differing in leaf shape, sepal shape, and its smaller flowers.

Where H. mutilum is native, it is variable in size and leaf shape but is still easily identified. However, in Canada, characteristics that typically separate H. mutilum from Hypericum boreale break down such that they are treated as subspecies. It is difficult to separate the two as species due to the high variability due to genetic and ecological influence. The difficulty in distinguishing the two is most apparent in

sympatrically with H. mutilum and in Nova Scotia the two become very difficult to distinguish. The description of Hypericum dissimulatum was a temporary solution to the problem. In 1980, Webb recognized H. dissimulatum as a hybrid between H. canadense and either H. mutilum or H. boreale.[2]

More towards the south, populations in the coastal plain from South Carolina to Florida west to Texas have more oblanceolate sepals and were named the variety latisepalum by Fernald in 1936. In these coastal populations, the terminal stem node is longer or absent as compared to the rest of the species, and thus the variety has been more recently promoted to a subspecies.[3]

The specific epithet mutilum means "mutilated" or "cut-off", as the Linnaean type was only a cut-off fragment of the plant. The name latisepalum means "broad-sepaled" and the name boreale means "northern".[4]

Description

Hypericum mutilum is a glabrous perennial or annual herb that is erect or decumbent, growing 15–60 cm (5.9–23.6 in) tall. The fibrous roots arise from the

capsule is 2–4 mm (0.079–0.157 in) long and 1.6–2.4 mm (0.063–0.094 in) wide, rounded at its summit.[4] The light brown seeds are 0.4–0.7 mm (0.016–0.028 in) long.[3][2] The herb flowers from July to September.[5]

H. mutilum subsp. mutilum has an apical internode that is shorter than the rest of the internodes. The leaves are variable in shape but are most commonly broadly ovate or suborbicular, and have a pale underside. The sepals are more broad above their middle. The inflorescence of the subspecies branches from two to ten nodes, with the branching being chiefly dichasial. The subspecies is distributed throughout the entire distribution of the species except for the northernmost regions and part of the coast of the Gulf of Mexico.[3]

H. mutilum subsp. latisepalum has well developed apical internodes that are longer than other internodes. The leaves are broadly ovate with pale undersides. The sepals are more or less imbricate and are wider above their middle. The inflorescence branches from one to four nodes and branches diffusely and monochasially distally. The subspecies only occurs in scattered populations in low grounds and coastal mud from New Jersey to Florida and west to Texas.[3]

H. mutilum subsp. boreale has shorter or absent apical internodes. The broadly ovate to elliptic leaves have no pale undersides. The sepals are not imbricate and are wider in their upper half. The inflorescence branches from two to six nodes, branching mostly dichasially. When the subspecies grows when submersed in water, the plants are nearly always sterile and have elongated stems. The subspecies occurs from

Newfoundland west to Manitoba, Wisconsin, and Minnesota and south to Virginia.[3]

Habitat and distribution

Hypericum mutilum grows in ditches, marshes, shorelines, and occasionally in moist woods and fields. In the United States it occurs up to 1,400 m (4,600 ft) and in Ecuador it occurs up to 2,300 m (7,500 ft).[6] It prefers a soil pH of 4.8 to 7.2.[7]

The plant is native to

Newfoundland, in the south to Florida, and in the west to Texas.[8] It has been introduced to France in Landes, to Italy in Tuscany, to Poland in Silesia, to Mexico (where it may be partly native), to Honduras, Ecuador, Peru, Brazil, New Zealand, and Hawaii. The populations discovered in France in 1934 and in Italy in 1834 seem to have been established for a long time.[3]

Ecology

Similar to some other species of Trigynobathys, H. mutilum grows in moist or muddy habitats where its seeds adhere to wading birds. The long-distance migrations of these birds is most likely the method by which the species has been introduced to Central and South America, where in some areas including Mexico and Ecuador the species appears to have been established for a long time.[3]

References

  1. ^ a b "Hypericum mutilum". eFloras.org. Flora of North America. Retrieved 25 October 2018.
  2. ^ a b 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). National Museums of Canada: 16.
  3. ^ a b c d e f g Norman K. B. Robson (1951). Studies in the genus Hypericum L. (Guttiferae) 8. Sections 29. Brathys (part 2) and 30. Trigynobrathys. Bulletin of the British Museum (Natural History). Vol. 1. British Museum (Natural History). p. 115-121.
  4. ^
    ISBN 0-442-22250-5
    .
  5. ^ Nathaniel Lord Britton, Addison Brown (1897). 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. Charles Scribner's Sons. p. 434.
  6. ISBN 9780812240030
    .
  7. ISBN 9780813541631
    .
  8. ^ "Taxon: Hypericum mutilum L." U.S. National Plant Germplasm System. Germplasm Resources Information Network. 2018. Retrieved 25 October 2018.
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