Oclemena

{{Short description|Genus of flowering plants}}

{{Automatic taxobox

|image = Oclemena nemoralis, Pancake Bay PP.jpg

|image_caption = Oclemena nemoralis (Bog-aster)

|display_parents = 3

|parent_authority = G.L.Nesom

|taxon = Oclemena

|authority = Greene

|synonyms_ref =

|synonyms =

• Acuminati Alexander
• Aster sect. Nemorali House
• Aster sect. Orthomeris (Torr. & A.Gray) Benth. & Hook.f.
• Aster subg. Orthomeris (Torr. & A.Gray) A.Gray
• Galatella sect. Calianthus Nutt.

}}

Oclemena is a small genus of North American flowering plants in the tribe Astereae within the family Asteraceae.[https://www.biodiversitylibrary.org/page/396130#page/7/mode/1up Greene, Edward Lee. 1903. Leaflets of Botanical Observation and Criticism 1(1): 4–5] in English[http://www.tropicos.org/Name/50200037 Tropicos, Oclemena Greene ]

It is native to northeastern North America, found in wet or dry woodlands, and sometimes in clearings in the woods, or in acid bogs and peat.[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=122605 Flora of North America Vol. 20 Page 78 Oclemena Greene]

The finely woolly stem grows in a zig-zag fashion to a height {{convert|30|-|100|cm|ft|0|abbr=on}}. It may be red at its base.

The lanceolate leaves are numerous, arranged in a spiral whorl around a single stem. They can be sharply toothed along the margin (as in O. acuminata) or smooth (as in O. nemoralis). The leaves contain sessile resin glands.

The flower heads consist of flat-topped pink to rose-violet ray florets and yellow disk florets. There are one to a few on a plant, growing on a slender peduncle. The disk flowers are abruptly expanded at the top. The scarious floral bracts consist of narrow chlorophyllous bands, tinted with purple along the midrib.

The stipitate ovaries are generally compressed and show on the surface minute, cylindrical glands. The fruit is a glandular achene with a double pappus of two bristled whorls.

The chromosome base number is x=9.

The Kew database [https://web.archive.org/web/19971118034813/http://www.rbgkew.org.uk/cgi-bin/web.dbs/genlist.pl?COMPOSITAE Vascular Plant Families and Genera] categorizes Oclamena under the genus Aster L. But taxonomically, Oclemena belongs to the North American clade of the tribe Astereae, as a basal member of one of the main branches.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.

; Species[http://dixon.iplantcollaborative.org/CompositaeWeb/default.aspx?Page=NameDetails&TabNum=0&NameId=77ca593f-1626-44fc-a5de-8017f72cdf3b Flann, C (ed) 2009+ Global Compositae Checklist ][http://www.theplantlist.org/tpl1.1/search?q=Oclemena The Plant List, search for Oclemena][http://bonap.net/NAPA/TaxonMaps/Genus/County/Oclemena Biota of North America Program 2013 county distribution maps]

File:Oclemena-acuminata01.jpg|Whorled Wood Aster (Oclemena acuminata)

File:Oclemena-nemoralis01.jpg|Bog Aster (Oclemena nemoralis)

• Oclemena acuminata (Michx.) Greene: Whorled wood aster, sharpleaf aster, white wood aster GA TN NC WV VA OH PA NJ DE NY CT RI MA VT NH ME NS NB QUE ONT NFL LAB
• Oclemena × blakei (Porter) G.L.Nesom (O. acuminata × O. nemoralis) : Blake's aster MI PA NJNY CT RI MA VT NH ME NS NB QUE ONT
• Oclemena nemoralis (Ait.) Greene: bog aster, bog nodding aster. MI DE MD PA NJ NY CT RI MA VT NH ME NS NB QUE ONT
• Oclemena reticulata (Pursh) G.L.Nesom: pinebarren whitetop aster. FL GA AL SC