TREE experts at City of York Council were helping police as they searched for missing Hull woman Joanne Nelson.

Officers believe two types of tree could be further vital clues in the search for Joanne, missing since St Valentine's Day.

Police want to identify areas where the western hemlock (tsuga heterophylla) and the birch tree grow together and York council staff have offered to help identify locations.

Searchers, who have visited many areas of East Yorkshire, as well as outlying Hull villages, were also urging landowners, farmers and anyone who grows both trees together to contact Humberside Police.

Meanwhile, forensic experts were testing a bag found on a footpath near to the railway line in Hull in February, to confirm it belonged to the 22-year-old.

Detective Superintendent Ray Higgins, leading the investigation, said: "I would like to appeal for landowners, farmers or private growers who grow two specific types of trees together: the western hemlock and the birch.

"The information has been received as part of on-going police inquiries and I urge anyone who may know of sites that contain two such trees growing together to contact the incident room immediately."

Detectives were contacting the Forestry Commission to find sites where the trees were grown.

Police also want to hear from landowners who have a gate made of tubular steel, which is set back from the road, on their grounds.

Officers were yesterday cutting back hedges in Strathcona Avenue, Hull, looking for Joanne's other possessions: a white coat, black boots and mobile phone.

Her fianc Paul Dyson, 30, from Hotham Road North, Hull, has been charged with her murder and is on remand.

Tree-growers or anyone with any information should phone the police incident room on 01482 334800.

Updated: 09:39 Saturday, March 19, 2005