Greater Knapweed

Greater Knapweed - Centaurea scabiosa

Description

Medium to tall robust somewhat bristly plant to 1.5 metres. Stems erect, branched above. Leaves usually pinnately lobed with oblong or linear segments. Flowerheads purple, large 30 to 50 mm the outer florets much longer than the inner.

Similar Species

Centaurea nigra

Identification difficulty
ID checklist (your specimen should have all of these features)

Leaves pinnately lobed; outer florets longer than inner 

Habitat

Rough grassy habitats, scrub and roadsides on dry calcareous soils.

When to see it

Late June to September.

Life History

Perennial.

UK Status

Widespread but local in England, scarcer or more coastal elsewhere in Britain.

VC55 Status

Occasional. Mainly found in the north east of Leicestershire and in parts of Rutland with most other VC55 records coming from railway verges. In the 1979 Flora survey of Leicestershire it was found in 26 of the 617 tetrads.

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2025+ | 2020-2024 | pre-2020

UK Map

Additional images

All NatureSpot records

Photo of the association

Large Knapweed Aphid

The Large Knapweed Aphid (Uroleucon jaceae) lives on various knapweeds (Centaurea spp.) and a few other species of Asteraceae, but not generally on other thistles. It is a large blackish aphid that can appear dark metallic green. The abdominal tergites 2-4 often have small marginal tubercles. The femora have the basal half pale and distal half dark, with a rather sharp transition between them. The tibiae are totally black. The siphunculi are reticulated over the distal 0.16-0.27 of their length and are 1.3-1.8 times the length of the cauda. The cauda is dark and bears 18-30 hairs. The body length of apterae is 3.0-4.5 mm long.