White wood aster (Eurybia divaricata) COSEWIC assessment and status report: chapter 6

BIOLOGY

The genus Eurybia is characterized by a flat-topped capitulescence, broad and apically rounded phyllaries, and terete ovaries. The phyllaries typically are ciliate on the margin and have a basally truncate green zone at the tip (i.e., shaped like a thumb nail). The pappus bristles are sometimes thickened near the apex but are of nearly uniform length. In some species, the leaves are both cordate and borne on a petiole, whereas in others they are sessile and taper to the base (Haines, 2001).

Physiology

Eurybia divaricata is a fall-flowering herbaceous perennial.  It prefers open, dry, deciduous forests with well-drained soils.  The phenology of Eurybia divaricata can be generalized as follows (Sharp et al., 1995):

Floral bud break:                   Early August

Capitulescence opening:     Mid-to-late August

Full flowering:                         1st to 3rd week of September

Early fruiting:                          Mid September

Reproduction/Dispersal

Shoots of Eurybia divaricata develop from the tips of rhizomes and form dense colonies. Seeds of Eurybia divaricata are wind dispersed with migration rates of 0.2 to 0.3 m per year (Singleton et al., 2001).  This is considered very low (Singleton et. al, 2001) and may explain why Eurybia divaricata has not colonized nearby woodlots which exhibit the same habitat characteristics.  There is no other information available on the reproductive ecology of this species.

Interspecific Interactions

There is no information available on interspecific interactions for this species.

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