Oclemena × blakei

Oclemena × blakei
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Oclemena
Species:
O. × blakei
Binomial name
Oclemena × blakei
Synonyms[2]
Homotypic synonyms
    • Aster × blakei (Porter) House
    • Aster nemoralis var. blakei Porter
Heterotypic synonyms
    • Aster nemoralis var. major Peck

Oclemena × blakei, commonly known as Blake's aster, is a hybrid of flowering plant in the aster family Asteraceae. It is native to northeastern North America. Its parent species are Oclemena acuminata and Oclemena nemoralis.

Description

The hybrid Oclemena × blakei is intermediate in appearance between its parent species. It is distinguished from its parents primarily by its leaves:[3][4][5][6]

Oclemena acuminata Oclemena × blakei
(O. acuminata × O. nemoralis) 		Oclemena nemoralis
Number of leaves below the inflorescence 10–22
Clustered and larger at the summit of the stem 		20–45 40–75
Uniformly sized and distributed
Width of leaf blades 15–60 mm wide 5–24 mm wide 2–12 mm wide
Leaf margins Prominently toothed with flat margins Small teeth Entire or nearly so, often with revolute margins
Flower heads 5–46 2–35 1–15
Ray flowers White or tinged with pink White to pink Pink to purple, seldom white
Habitat Forests Overlapping habitat of parents Bogs, fens, mossy lake shores

Oclemena × blakei is sometimes confused with Eurybia radula. The latter has pale blue-violet ray flowers and 4–5 rows of phyllaries (bracts) with rounded tips,[7] whereas the former has white to pink ray flowers and 1–2 rows of phyllaries with pointed tips.

Taxonomy

Oclemena × blakei was first described as Aster nemoralis var. blakei by the American botanist Thomas Conrad Porter in 1894.[9] Porter named the variety in honor of the botanist who collected its type specimen in Gilmanton, New Hampshire 30 years earlier.[10] In 1920, the American botanist Homer Doliver House concluded that Aster nemoralis var. blakei Porter "should more properly be regarded as a hybrid" of Aster acuminatus and Aster nemoralis.[11][12] The resulting hybrid name Aster × blakei (Porter) House remained in use for the rest of the 20th century. In 1995, the American botanist Guy L. Nesom published the name Oclemena acuminata × Oclemena nemoralis.[1] As of December 2025, the hybrid name Oclemena × blakei (Porter) G.L.Nesom is widely accepted.[2][13][14][15]

In the Report of the State Botanist of 1893, Charles Horton Peck described a variety of Aster nemoralis collected in northern Herkimer County, New York along with the typical variety. As described by Peck,[16] the new variety was much larger than Aster nemoralis with a longer stem, more flower heads, and larger leaves. As of December 2025, the name Aster nemoralis var. major Peck is considered to be a synonym of Oclemena × blakei.[17]

Distribution and habitat

Oclemena × blakei is native to eastern Canada and northeastern United States:[2][18]

  • Canada: New Brunswick, Newfoundland, Nova Scotia, Ontario, Prince Edward Island, Quebec
  • United States: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island, Vermont

There are unconfirmed reports that the hybrid occurs in Michigan and Pennsylvania as well.[19][20]

Conservation

As of December 2025, Oclemena × blakei is not globally ranked by NatureServe.[21] It is secure (S5) in Nova Scotia and critically imperiled (S1) in Connecticut but no other state-level ranks are listed.

References

  1. ^ a b "Oclemena × blakei (Porter) G.L.Nesom". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 4 December 2025.
  2. ^ a b c "Oclemena × blakei (Porter) G.L.Nesom". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 4 December 2025.
  3. ^ Brouillet & Simon (1981), Table 1.
  4. ^ Brouillet, Luc (2006). "Oclemena". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 20. New York and Oxford: Oxford University Press. Retrieved 5 December 2025 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  5. ^ Haines (2011), p. 420.
  6. ^ "Oclemena". Go Botany. Native Plant Trust. Retrieved 5 December 2025.
  7. ^ Brouillet, Luc (2006). "Eurybia radula". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 20. New York and Oxford: Oxford University Press. Retrieved 5 December 2025 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  8. ^ Britton & Brown (1913), p. 432, Fig. 4351.
  9. ^ "Aster nemoralis var. blakei Porter". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 4 December 2025.
  10. ^ Porter (1894).
  11. ^ "Aster blakei (Porter) House". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens. Retrieved 18 December 2025.
  12. ^ House (1920), p. 241.
  13. ^ "Oclemena × blakei (Porter) G.L.Nesom". WFO Plant List. Retrieved 4 December 2025.
  14. ^ NRCS. "Oclemena ×blakei". PLANTS Database. United States Department of Agriculture (USDA). Retrieved 6 December 2025.
  15. ^ "Oclemena × blakei (Porter) G.L.Nesom". Database of Canadian Vascular Plants. Retrieved 6 December 2025.
  16. ^ Peck (1894), p. 155.
  17. ^ "Aster nemoralis var. major Peck". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 18 December 2025.
  18. ^ Brouillet, Luc (2006). "Oclemena × blakei". In Flora of North America Editorial Committee (ed.). Flora of North America North of Mexico (FNA). Vol. 20. New York and Oxford: Oxford University Press. Retrieved 6 December 2025 – via eFloras.org, Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
  19. ^ Kartesz, John T. (2014). "Oclemena X blakei". State-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). Retrieved 6 December 2025.
  20. ^ Kartesz, John T. (2014). "Oclemena X blakei". County-level distribution map from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). Retrieved 6 December 2025.
  21. ^ NatureServe (5 December 2025). "Oclemena × blakei". NatureServe Explorer. Arlington, Virginia. Retrieved 9 December 2025.

Bibliography

  • Reznicek, A. A.; Voss, E. G.; Walters, B. S. (February 2011). "Oclemena nemoralis (Aiton) Greene". Michigan Flora Online. University of Michigan. Retrieved 6 December 2025.
  • Nesom, G. L. (2001). "An anomalous population of Aster (Asteraceae: Astereae) sensu lato in Michigan". SIDA, Contributions to Botany. 19 (3): 625–632. JSTOR 41967889.
  • "Oclemena × blakei (Porter) G.L.Nesom". Global Compositae Database. Compositae Working Group (CWG). 2025. Retrieved 10 December 2025.
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