The Oclemena Greene genus

Remark The words or terms in red (actually dark orange) in the text are defined in a glossary.


aug_03_01.gthmb can't be loaded. Oclemena is a small genus of flowering plants from the Asteraceae family. The genus was formerly categorized under the genus Aster Linnaeus, but taxonomically, Oclemena belongs to the North American clade of the tribe Astereae, as a basal member of one of the main branches. Oclemena is considered a monophyletic group; it appears to be among the basal lineages of the North American clade of Astereae. The genus is defined on the basis of fruit and phyllary traits.

The genus is native to northeastern North America; the plants of the genus are found in wet or dry woodlands, and sometimes in clearings in the woods, or in acid bogs. The genus has 4 species, including one hybrid.

The Oclemena are perennials, that grow in more or less open clones or in dense clusters. The finely woolly stem of the plants grows somewhat in a zig-zag fashion with a height between 1 to 3 feet, and it may be red at its base.

The numerous leaves are lanceolate, arranged in a spiral whorl around a single stem. They are reduced in size toward the base of the stem. They can be sharply toothed along the margin, as in Oclemena acuminata or smooth as in Oclemena nemoralis (picture above).

The flower heads consist of flat-topped pink to rose-violet ray florets and yellow disk florets, both florets being fertile. The flower heads are one to a few on a plant, growing on a slender peduncle, The disk flowers are abruptly expanded at the top.

The ovaries are stipitate, they are are generally compressed and show on the surface minute, cylindrical glands.

The phyllaries are narrow, in 3 or 4 series, with green zones along the midveins, with scarious margins and acute apices

The fruit is a glandular achene with a double persistent pappus of two whorls of tan bristles.

Plants belonging to the genus have a chromosome base number of 9.

The Oclemena of Québec

Of the four species of Oclemena native to North America, three are found in Québec:

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