Yellow-wort Blackstonia perfoliata

Yellow-wort is a native plant found in dry grasslands on shallow chalk and limestone soils. This plant will not grow on shaded sites. It is a perennial and flowers from June to October. The stem and leaves are bluish-green and are hairless. The oval leaves are stalkless and form a loose rosette at the base of the stem. The leaves on the stem are in pairs with their bases fused together, making it appear as if the stem passes through the middle of a single leaf. Yellow-wort grows to between 15 and 45 cm high.

The petals are yellow and there can be between six and eight on each flower. They are joined at the base into a short tube. The Yellow-wort is a member of the gentian family and like other members of this family the flowers close up in the early afternoon.

Current Status

Yellow-wort is distributed throughout most of southern Britain, extending as far north as north-west Yorkshire and Northumberland. This plant is thought to have expanded its range in recent years, especially in northern England, due to its inclusion in commercial wildflower mixtures on road verges and other landscaped sites.

The plant is quite abundant within Hull. It is found on bare and open sites, usually with an alkaline substrate. A recent survey carried out by the Hull Natural History Society (HNHS) found the plant to be much more common than had been expected. It was found to be the dominant species on bare sites in some parts of the city. This plant is thought to be increasing within the City.

Current Factors Affecting Yellow-Wort

• Loss of habitat is the main factor affecting Yellow-wort in Hull. The plant occurs on a number of disused industrial sites, in particular old railway sidings. Many of these sites will be lost to development in the near future.

Current Action

Legal Status

All wild plants are given limited protection under UK law. Under the Wildlife and Countryside Act (1981) it is illegal to uproot any wild plant without permission from the landowner or occupier. The Countryside and Rights of Way Act (2000) has increased the penalties for offences so that they are sufficiently high to act as a deterrent.

Management, Research and Guidance

Over the period of 1998 to 2000 members of the HNHS undertook a project to map the distribution of plants within the Hull area. Yellow-wort was included in this project and a distribution map for the species has been produced.

Action Plan Aims 

1. To determine the current distribution of Yellow-wort within Hull.
2. To monitor known Yellow-wort sites within Hull.

What We Are Going to Do

What We Can All Do

• Let the Biodiversity Partnership know if you see Yellow-wort in Hull.
  
  
• Be aware that uncut grassland on industrial sites can be ideal for rare plants and is better for wildlife than closely mown lawns.
   

Links With Other Action Plans

Management of Grassland and Industrial Land will be very important for the Yellow-wort within Hull. Yellow-wort is found in similar habitats to Bee Orchids and management for both species will be similar.

References

Akeroyd, J. (1999) The Encyclopaedia of Wild Flowers. Parragon, Bath.

Crackles, F.E. (1990) Flora of the East Riding of Yorkshire. Hull University Press & Humberside County Council, Hull.

Marshall, B.G. (2001) The Comparative Biodiversity and Conservation Value of Brownfield and Greenfield Development Sites. MSc Dissertation (unpublished).

Middleton, R. (2000) The Plants of Hull: A Millennium Atlas. (Retrieved January 2002 from http://www.hull.ac.uk/hullflora)

Stace, C. (1997) New Flora of the British Isles. Cambridge University Press, Cambridge.

Streeter, D. (1998) The Wild Flowers of the British Isles. Midsummer Books, London.