Species
There are well over a 1000 species of plant and insect recorded on Portsdown Hill. It would be quite possible to discover more if time were spent looking for them. Insects are especially well-hidden and difficult to identify, even if you can find them.
During the summer there are many colourful flowers and the grass is alive with a variety of insect life. Butterfly food plants characteristic of chalk grassland, e.g. Rock Rose and Kidney Vetch, remain but are often struggling in tall grass or in association with the small areas of low soil fertility. Chalkhill and Small Blue butterflies are to be found, but at lower numbers than previously. There are good populations of those insects associated with taller grass (Marbled White Butterfly) or scrubby areas (Great Green Bush Cricket).
There are several species which are characteristic of ancient chalk grassland, e.g. Horseshoe Vetch and Bastard Toadflax. These plants have poor dispersal mechanisms and are very slow to colonise new sites.
The plants show a variety of strategies for coping with their environment. Many have deep root systems, storage organs or are parasitic to order survive drought. Many resist grazing by being spiny or by packed with distasteful chemicals. Some have combinations of these features.
