Field of Science

Friday Fabulous Flower - Aster?

Another weekend that was too busy for words, other than maybe yikes!  Sorry FFF gets so easily put off.  While TPP is sort of on a composite kick, it is that time of year.  But at least this isn't another SYC.  Technically this isn't an Aster, which is now about 200 species strong but entirely restricted to Eurasia.  So if the plant is native to the Americas, and was formerly as Aster, it is now placed in a new genus; there are several.  This plant always flowers in the fall, and it does well in some semi-shady locations.  The flower heads (remember they are inflorescences) are small at about 1 cm in diameter, but they are numerous.  The ray flowers are white while the disk flowers start out yellow and then change to red as they transition from dispersing pollen to accepting pollen (TPP isn't sure why).  But it makes for a rather nice display, especially from close range.  Generally this particular species, Eurybia divaricata, is called the white woodland aster (formerly Aster divaricatum) (note the change in gender of the specific epithet).  

1 comment:

Katherine Wagner-Reiss said...

The yellow disc flowers are young, unpollinated, and offer the insects nectar; whereas the red disc flowers are older, pollinated, and are plumb out of nectar! This signaling via pigments is easy ( just making some anthocyanin) and is beneficial to both the Eurybia
( insects land on the flowers that need pollinating) and to the pollinators ( saves them the energy of visiting flowers with no rewards)!
I just learned that Lantana also uses a similar signaling method.
Thank you so much for your picture of Eurybia showing the two colors; I've never seen ( or maybe never noticed?) that before.