The genus Symphyotrichum Nees

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


sep_18_13.gthmb can't be loaded. The species of the Symphyotrichum genus are annual or perennial, that go from a quite small size, around 1 inc, to 2 meter in height. They have both basal and cauline leaves, and are usually heterophyllous, somme species strongly so. Depending on the species the involucre is somewhat tiny, 4 mm in diameter, or of a respectable size, 22 mm in diameter, with numerous phyllaries in several series. The flower heads have usually both disc florets and ray florets that are both fertile. The disc florets are white, pink, blue, or purple and the ray florets are yellow to white, becoming purplish to reddish or pinkish at maturity. The fruits have a persistent pappus of 20 or more bristles.

Botanists usually restrict the genus to those species with chromosome number of value 5, 7, 8 13, 18 and 21 and exclude members of the subtribe Symphyotrichinae. The genus belongs to the Asteraceae family.

Name

In Greek : so that Symphyotrichum would refer to a plant having fruits with pappus and growing together, the case of the disk florets.

The Symphyotrichum of Québec

There are over ninety species of Symphyotrichum, and about 80 grow in North America. Several species are naturalized in Europe (Symphyotrichum lanceolatum and Symphyotrichum novi-belgii notably). The following species, subspecies, varieties and hybrids can be found in Québec: Species are distinguished on the basis of differences in habit, leaf shape, involucre size, phyllary shape and chlorophyllous zone pattern, and fruit traits.

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