Oclemena

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Oclemena
Oclemena nemoralis, Pancake Bay PP.jpg
Oclemena nemoralis (bog aster)
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Subfamily: Asteroideae
Tribe: Astereae
Subtribe: Oclemininae
G.L.Nesom
Genus: Oclemena
Greene [1]
Synonyms [2]
Heterotypic synonyms
    • Aster sect. NemoraliHouse
    • Aster sect. Orthomeris(Torr. & A.Gray) Benth. & Hook.f.
    • Aster subg. Orthomeris(Torr. & A.Gray) A.Gray
    • Galatella sect. CalianthusNutt.

Oclemena is a genus of flowering plants in the tribe Astereae within the family Asteraceae. All species in the genus are native to eastern North America. The species were originally included in the genus Aster so they are often referred to simply as asters. Since their flower heads are nodding in bud, they are sometimes called nodding-asters.

Contents

Description

Oclemena species are perennial, herbaceous plants that propagate via a swollen tuber at the tip of a slender, elongated rhizome. Stems are erect and unbranched, with dense long hairs. Stem leaves are sessile (or short-petiolate) and alternate. Leaf blades are sparsely dotted with short glandular hairs, each with a yellow to orange resin head. Leaf margins are either serrate (O. acuminata) or both entire and revolute. The inflorescence is either a single flower head (O. nemoralis) or a corymb of 2–46 flower heads on long, slender peduncles, nodding in bud (except O. reticulata). A flower head has 7–25  ray flowers, white or pink, and 14–35  disc flowers, pale or pinkish yellow, reddening at maturity. The chromosome base number is x=9. [3] [4] [5]

Taxonomy

Oclemena acuminata illustrated as Aster acuminatus in 1913 Oclemena-acuminata01.jpg
Oclemena acuminata illustrated as Aster acuminatus in 1913

In 1903, the American botanist Edward Lee Greene established genus Oclemena by segregating two species, Aster acuminatusMichx. and Aster nemoralisAiton. [3] Greene, initially drawn to this group of plants by the nodding habit of their flower heads in bud, had been using the name Oclemena acuminata on the labels of herbarium specimens since 1897. In 1995, the American botanist Guy L. Nesom segregated two additional taxa, Aster nemoralis var. blakeiPorter and Aster reticulatusPursh. [7] Nesom considered Oclemena to be monophyletic but closely related to Doellingeria Nees. [4] A major treatment of genus Oclemena appeared in Flora of North America in 2006: [5]

Scientific nameCommon nameYear describedYear publishedDistribution
Oclemena acuminata (Michx.) Greenewhorled wood aster18031903Eastern Canada, Eastern United States
Oclemena × blakei (Porter) G.L.Nesom
(O. acuminata × O. nemoralis)		Blake's aster18941995Eastern Canada, Northeastern United States
Oclemena nemoralis (Aiton) Greenebog aster17891903Eastern Canada, Northeastern United States
Oclemena reticulata (Pursh) G.L.Nesompinebarren whitetop aster18131995Southeastern United States

As of December 2025, the generic name OclemenaGreene is widely accepted. [8] [9] [10] [11]

Oclemena belongs to the North American clade of the tribe Astereae, as a basal member of one of its main branches. [12]

Distribution and habitat

Oclemena species are native to eastern North America. [5] [13] Oclemena acuminata is the most wide-ranging species, from the Appalachian Uplands of Newfoundland to the southern tip of the Appalachian Mountains in the U.S. state of Georgia. In contrast, Oclemena reticulata îs restricted to the extreme southeastern United States where other species of Oclemena are not found. Oclemena nemoralis and Oclemena × blakei are boreal species that prefer the cold acidic bogs of eastern Canada and northeastern United States.

References

  1. ↑ "OclemenaGreene". International Plant Names Index (IPNI). Royal Botanic Gardens, Kew; Harvard University Herbaria & Libraries; Australian National Botanic Gardens . Retrieved 10 December 2025.
  2. ↑ "OclemenaGreene". Global Compositae Database. Compositae Working Group (CWG). 2025. Retrieved 10 December 2025.
  3. 1 2 Greene (1903).
  4. 1 2 Nesom (1995), pp. 175–178.
  5. 1 2 3 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.
  6. ↑ Britton & Brown (1913), p. 432, Fig. 4352.
  7. ↑ Nesom (1995), p. 264.
  8. ↑ "OclemenaGreene". Plants of the World Online . Royal Botanic Gardens, Kew . Retrieved 10 December 2025.
  9. ↑ "OclemenaGreene". WFO Plant List. Retrieved 4 December 2025.
  10. ↑ NRCS. "Oclemena". PLANTS Database. United States Department of Agriculture (USDA). Retrieved 10 December 2025.
  11. ↑ "OclemenaGreene". Database of Canadian Vascular Plants. Retrieved 10 December 2025.
  12. ↑ Brouillet, L., G.A. Allen, J.C. Semple, and M. Ito. 2001. ITS phylogeny of North American asters (Asteraceae: Astereae). Abstract. Botany 2001, August 2001. Albuquerque, N.M.
  13. ↑ Kartesz, John T. (2014). "Oclemena". State-level distribution maps from the North American Plant Atlas (NAPA). Biota of North America Program (BONAP). Retrieved 10 December 2025.

Bibliography

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