ESSEX   BOTANY   AND   MYCOLOGY  GROUPS 

Following the introductory paragraph to each taxon, the records are set out in columns. The first being the letter and alternative number (in brackets) code for the 100 x 100km square, followed by the 10 x 10km square number, arranged in conventional order from south to north, moving from west to east; the second column gives the 1 x 1km square or the 100 x 100m square Ordnance Survey grid reference if known; the third the vice county, and the final column the available details of the individual record. Approximate grid references for older records are suffixed by a?

Chara vulgaris L. sensu lato

Several forms of this taxon have been given varietal names, such as vulgaris, longbracteata, papillata, crassicaulis and refracta. Having grown these in culture however, it is pretty obvious that they are not distinct genetic varieties but are simply ecomorphs, as the same plants change from one form to another as they grow. Quite what causes the switch between the forms is unclear. It does not seem to be correlated with daylength, but I suspect that the development of extended bracteoles and long spine cells is a response to predation, as water mites and juvenile Limnaea snails are particularly partial to the antheridia. Thus it is possible for a single plant to express both the papillata and the longibracteata morphology simultaneously.

I propose eventually therefore to reorganize this dataset under one heading with notes covering the type of expression exhibited by particular populations, and abandon the clearly illegitimate varietal names.

Chara vulgaris var. crassicaulis (Schleicher. ex A. Braun.) Kutz.