This work by Somekh is titled The Union of the Four Species.
For the Jewish Sukkot holiday four species of plants are selected:
One with taste and with odor-Atrog (cirron),
One with taste and odorless- Lulav (palm branch),
One with odor but tasteless- Hadas (myrtle),
One odorless and tasteless- Arava(willow).
According to one of the explanations the four species represent four types of persons who become united under the Sukkah. The holiday starts this year on Wednesday night October 8th.