The term succubous is used to describe the way in which the leaves of a liverwort are attached to the stem. If one were to look down from above (dorsal side) on a plant where the leaf attachment is succubous, the lower edge of each leaf would overlap the next lower leaf along the stem. Because of this, the lower edge of each leaf is visible from above, but the edge of the leaf closer to the tip of the stem is obscured by a neighboring leaf. The opposite of succubous is incubous.
References
Succubous Wikipedia(Text) CC BY-SA