Yesterday evening was only the fourth time since the beginning of April when I've had the opportunity to photograph in the garden — a somewhat worrying statistic for me. I've been fortunate enough to be able to travel this summer, but not being out in the garden often enough to observe the seasonal progression has been a bit disappointing.
Stemless carline thistle or dwarf carline thistle is native to the mountainous areas of central and southern Europe. The epithet acaulis means “without a stem”, but as you can clearly see in this photograph, this plant certainly has one. That suggests that this is either subspecies simplex (a stemmed subspecies of the plant) or a garden hybrid with Carlina acaulis subsp. simplex as part of the genetic mix.
In addition to the usual edibility (a globe artichoke substitute!) and medicinal use information often detailed in the Plants for a Future database, the entry on Carlina acaulis lists another use: weather forecasting. PFAF cites a reference that suggests the dried flowers of Carlina acaulis can be used to measure humidity, whereas the mature flowers of a plant will close prior to a rainfall. I'll have to keep a closer eye on them to verify the latter...
More information can be found on Wikipedia, including a photograph of a plant with a sessile (acauline) flower. A botanical illustration of Carlina acaulis is available via Thomé's Flora von Deutschland.