Radicchio is a close relative of common chicory (Cichorium intybus), a hardy perennial native to Eurasia but naturalized throughout much of North America. It is often found along roadsides and in waste places, especially on limestone soils.
The chicory species including radicchio have a common, interesting flowering behavior: The blossoms open early in the morning and close five hours later. Linnaeus, observing this tendency, planted chicory in his floral clock in Uppsala, Sweden. There, the flowers opened at 5 a.m. and closed at 10 a.m..
In Basel, the radicchio flowers are completely closed by noon, thus late risers miss out on these beautiful blooms.