Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich.
Centaurea
Common knapweed (C. nigra), perhaps the single most abundant Centaurea species of England
An example of divided leaves of a centaury (C. bella)
Centaurea tchihatcheffii (locally known as Yanardöner), a highly distinctive and rare knapweed endemic to Turkey
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles can also occur all over the plant – on the stem and on the flat parts of the leaves. These prickles protect the plant from herbivores. Typically, an involucre with a clasping shape similar to a cup or urn subtends each of a thistle's flower heads. The typically feathery pappus of a ripe thistle flower is known as thistle-down.
Milk thistle flowerhead
Cirsium arizonicum, showing arachnoid cobwebbiness on stems and leaves, with ants attending aphids that might be taking advantage of the shelter.
Thistles on Calton Hill in central Edinburgh, Scotland, 2023
Carduus nutans in the early morning light.
