FLORA IN VOLCANIC AREA
In the crater of the Vulcano Solfatara is a remarkable variety of plant species, also very different from one and another for climatic and soil requirements; this is due mainly to two factors:
a) The volcanic activity that elevates the temperature of the rhizosphere and prevents the survival of vegetation or imposes it an anomalous adaptation with predominantly superficial radical tissue.
b) The orography makes the north side sunnier, dryer and covered with Graminaceae, more humid and shady is the opposite side where are a mesophilic forest, some species of ferns (Pteridium aquilinum, Asplenium adiantum nigrum, Cystoperis fragilis), chestnut trees (Castanea sativa Miller) and butcher's broom (Ruscus aculeatus).
The crater floor offers large areas of Mediterranean plants with heather (Erica arborea), strawberry tree (Arbutus unedo), Sarsaparilla (Smilax aspera L.), rock rose (Cistus salvifolius), myrtle (Myrtus communis) and broom (Cytisus scoparius L., Spartium L.). There are also two orchids, the heart-shaped Serapis (Serapias cordigera L.) and the greater Serapis (Serapias vomeracea B.)
Among trees the following species are widespread: the holm-oak (Quercus ilex), the black locust (Robinia pseudoacacia L.) and the eucalyptus (Eucalyptus camaldulensis), here grown for its undoubted quality in offering shade and shelter from the wind and for its ability to adapt even in areas more directly influenced by the "volcanic activity". Of all the plants of the Solfatara of Pozzuoli the most unique and perhaps less easy to find is the cistus (Cytinus hypocistis L.); only the experts know that you must look at the foot of the rock roses (cystus salvifolius L.) since, as its name indicates, it is a parasitic plant of rock roses. Its roots are fixed on those of rock rose and draw nourishment, not being able to process chlorophyll synthesis. The useless leaves are reduced to squamae, while the globular flowers with their deep yellow and red colours, grow low to the ground often hidden by the dry leaves.