Peltigera aphthosa

Silver-edge pelt is a common and widespread lichen species in the forests of British Columbia. It is common in the Kamloops area in higher elevation Douglas-fir forests where it frequently occurs on the shaded forest floor.

There are about 30 species of pelt lichens (Peltigera) in BC. As with all lichens, silver-edge pelt consists of fungi and algae growing together to form one organism. Most species have one type of algae but a few species like silver-pelt lichen are distinct in that they have two types of algae. The dominant algal species is a green algae that gives the lichen a beautiful grassy green colour when the thallus is moist.

When dry, the thallus becomes a dull bluish green colour.

The underside of silver-pelt lichens are white along the upper underside that abruptly turn black in colour near the lower edge of the thallus.

Like other lichens, the fungal portion may produce spores in pie-shaped brown or black disk-like structures on the upper edges of the thallus that are called aphothecia. They release fungal spores but these do not contain the algal partner.

In many species of pelt lichens, the dominant algae partner is actually a photosynthetic bacteria that is sometimes called a blue-green algae. This is apple pelt, a common pelt lichen with a distinctive blue-green colour. Other pelt species with blue-green algae are similar and are more of a dark olive green colour whereas species with a dominant green algal partner are more of a grass green colour like that of silver-edge pelt.

Here you can see the surface of silver-pelt lichen is dotted by round black-like structures. These are called cephalodia and are small colonies of blue-green algae, Nostoc which are capable of fixing nitrogen, an important property that likely provides the lichen with a source of nutrients.