Porella, the only genus of the family Porellaceae, consists of about 180 species, which live preferably in the tropics on rocks or bark. 7 species can be found in Europe, 5 in germany. In most cases the plants are pinnate and dark or black green. They are bisexual. Many species have a pepperlike flavour in fresh state.
The leaves of the plants of this genus are divided in two oval or round lobes. The upper lobe is bigger than lower lobe, which is smaller or of about the same size as the round or oval underleaves. All those caracteristics can been seen rather well on the picture on the right.
Porella platyphylla is a typical member of the genus. The leaves (i.e. the lobes of the leaves and the underleaves) are entire or at most with some sporadic muticous teeth. The lower lobes are a bit broader than the stem and are decurrent (what can't be seen on the picture). They may be a bit dentate at the sides. The cells of the leaves contain about 20-30 small oil bodies.
Porella platyphylla can be found on the whole northern hemisphere. It grows on rocks or bark, sometimes even on earth. Still sometimes ago it was a rather common species in germany. Nowadays it is nearly dissappeared in the lowlands. Only in the mountains it is still more frequent.