The Cortex also contains a tissue called Sclerenchyma . The aerial stem usually has an Actinostele . The Xylem is composed of Tracheids . These have elaborate Secondary Cell Wall thickenings, unlike the Hydroids of Bryophyta. There are numerous Pits present in the cell walls.
Pits are more numerous on the end walls where the Tracheids overlap.
This facilitates Longitudinal Transport . Tracheids represent one of the most fundamentally important adaptations for terrestrial plants because of their two major functions, but especially because of their superior ability to facilitate long distance transport of water. They are the only type of Tracheary Element present in most land plants. Flowering Plants contain Vessel Members which are more specialized and varied in their structure. The Phloem contains Sieve Cells .