Roots are typically branching cylindrical structures that develop underground to facilitate extraction of moisture and nutrients from the soil, often in association with hyphal networks of soil-dwelling fungi. In contrast, epiphytes and epiliths, which grow entirely above the ground, often develop aerial roots that absorb moisture from their environment. In vascular plants, the root apex is a growing tip where both the root cap and the primary root tissues are produced. Lateral roots are initiated some distance from the root apex, by cell divisions in the pericycle, among differentiated cells that have retained meristematic capacity.