Previous work

Although all of the records presented on the maps have been collected in the last three years, information on change can only be obtained by comparing these data with previous, dated records. This kind of information takes two different forms - the body of published information and the preserved plant material in various herbaria.

Published works

The most important recent study has undoubtedly been Crackles' "Flora of the East Riding of Yorkshire", published in 1990. Although it covers the whole of Watsonian vice-county 61, it presents a considerable body of data about the city of Hull and its close surrounds. It is also the only work that can give a broader context to the city's plants and their possible origins. The species maps presented in the flora are essentially the records collected between 1950 and 1990. Where considered important, references to this work have been made in the map captions presented here. Since Crackles' "Flora" is still available unnecessary duplication has been avoided and it will be assumed throughout that the reader will have access to this work.

In 1938 the Hull Scientific and Field Naturalists' Club (eventually to become the Hull Natural History Society) published an occasional paper by A.K.Wilson entitled "The adventive flora of the East Riding of Yorkshire". This small booklet of 28 pages provides a plethora of information on the plants that had arrived in Hull either as dockland or seed aliens or as garden escapes. As this work is now rather difficult to obtain, I have taken the liberty of quoting liberally from it where I think it gives insight into trends and origins.

One of the great milestones in East Yorkshire botany was the publication in 1902 of J Fraser Robinson's "Flora of the East Riding of Yorkshire". Robinson was one of the founder members of the Hull Scientific and Field Naturalists' Club and although the work covers the whole riding, there is great emphasis on the area within 20 miles of Hull. Robinson drew extensively on the knowledge base of the local botanists of the time and presents a clear picture of the state of Hull's flora. Where Robinson makes particular mention of a plant in the Hull area I have added this information to the map captions.

Herbaria consulted

There are three major sources of herbarium information that have been consulted in the course of preparing the map captions. Two of these collections are held in the University of Hull Herbarium and the third by Hull Museums. Catalogues of the two University of Hull Herbarium collections are available via the WWW and may be searched easily at

http://www.hull.ac.uk/geog

The Hull Museums have recently aquired the Willoughby Smith herbarium from the Beverley Municipal Museum. This material had been presented to Beverley by Hugh Bernard Willoughby Smith in 1910. Along with this collection was a series of sheets prepared by Mr J R Waller, a large number of which are for the Hull area. These sheets appear to represent an attempt at a systematic collection of plants from the area in the 1880s and 1890s. Strangely no mention of this collection is made by Robinson in his 1902 flora, although many of the localities given for the more unusual plants are identical, neither is it mentioned by Crackles (1990). Reference to this material will be indicated by HUM.

The University of Hull Herbarium holds two collections containing plants from the local area. The A K Wilson collection consists of about 2000 sheets of predominantly local material collected mainly in the 1930s and 1940s. This seems to be the herbarium material originally held by the "Municipal Technical College" and designated HLL by Kent (1957), although I do not know of any documentation to support this hypothesis. The collection may not be complete, there are certainly no sheets for the family Apiaceae. Along with the Wilson material are three separate folders of sheets prepared for the British Botanical Competition of 1864. All of the mounted specimens are all from the "County of Hull" but, presumably in line with the competition rules, do not bear the name of the collector. For the purposes of this work they have been designated BBC.

The main University Herbarium collection was established by R D'O Good in the early days of Hull's Botany department and although it contains sheets from many older herbaria, there is a substantial amount of material from the Hull area. Most of the local material dates back to the 1930s, with a substantial number of sheets from the 1950s. In line with Kent's nomenclature, this material will be designated HLU.

I have included information gleaned from these herbarium sources in the map captions for all but the most abundant taxa. An absence of material in any of these collections cannot be construed as an absence in the region. Some of the commonest plants are hardly represented.