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

Species profile

Common names
Greater Knapweed
Species group:
flowering plant
Kingdom:
Plantae
Order:
Asterales
Family:
Asteraceae
Records on NatureSpot:
68
First record:
30/06/2011 (Calow, Graham)
Last record:
23/08/2025 (Calow, Graham)

Total records by month

% of records within its species group

10km squares with records

The latest images and records displayed below include those awaiting verification checks so we cannot guarantee that every identification is correct. Once accepted, the record displays a green tick.

In the Latest Records section, click on the header to sort A-Z, and again to sort Z-A. Use the header boxes to filter the list.

Latest images

Latest 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.