It is considered that they probably represent a stem group of living tardigrades.

Asteroxylon is probably a stem group to the Drepanophycaceae.

The placement of Dinocaridida is uncertain: they appear to be a stem group to arthropods.

The relationship of stem groups to the angiosperms is important in determining the evolution of flowers.

However it lacks any clearly diagnostic characters and its affinity is best considered to lie in an unresolved stem group.

Usually the stems have thicker walls than those of the green stem group.

As time goes on, they can be placed in the stem group to an ever smaller clade.

It follows from the definition that all members of a stem group are extinct.

The stem group of birds would be all the earlier Aves minus the crown group.

Isoclinism divides p-groups into families, and the smallest members of each family are called stem groups.