Alchemilla vulgaris; the common lady's-mantle is an apomictic species that is divided into a number of micro species. In the broad sense of A. vulgaris the following micro species can be found on Iceland:
Alchemilla glomerulans (common)
Alchemilla filicaulis (common)
Alchemila wichurae (rather rare)
Alchemilla glabra (rare)
Alchemilla subcrenata (rare)
Alchemilla mollis (introduced ornamental plant, towns & villages)
In the strict sense of A. vulgaris: this micro species is not Icelandic.
This is an apomictic species. It does not produce fertile pollen. Thus, cross- or self-fertilization can not take place. The seeds of the plants have the same genetic make-up of the parent plant.
So, how can one identify these micro-species? Here are a couple of identifying differences:
A. filicualis has hairs on the leaf-petioles that stand outwards where A. glomerulans' hairs on the leaf-petioles are pressed onto these petioles. The leaf-color of A. filicaulis is darker green than that of A. glomerulans. Where both species grow together the differences in color is striking. One can also observe where these two plants grow together that the size of the leaves of A. glomerulans is larger than those of A. filicaulis.
A. wichurae usually has red stems and red fringes on the leaves. The central flower of the inflorescence is red coloured.
A. glabra and A. subcrenulata are both almost hairless on the petiole's. A. glabra has leaves which have wide openings between the left and right bottom part of the leaves where in A. subcrenata the bottom lobes almost overlap each other.
A. mollis is a densely haired plant with relative large leaves. It can best be distinguished from other species by their light-green (yellowish-green) leaves.
Then there are the following lady's-mantle species that occur on Iceland:
These are true species not included in the A. vulgaris senso lato group.
They can both be identified by the fact that the leaves are more incised than the leaves of the species within the A. vulgaris group.
Note of interest. The name "Lady's-mantle" refers to the fact that they have been used as a traditional medicine for complications in women's menstruation. The name Alchemilla has anther background. These plants (like many other plants too, though) have a water repellant surface. As a result fine water droplets run off the leaves. These water droplets - according to information I found on wikipedia - were used by the medieval chemists who tried to turn iron into gold (the Alchemists) in their attempts. These water droplets were regarded as the most pure form of water.
They are members of the Rose family (Rosaceae). The Icelandic name of this species is Maríustakkur.