The two drawings below attempt to show the anatomy of leaf gaps from a 3-D Perspective. Three Dimensional Model of a siphonostele with leaf gaps. The stele is re - unified above the node and appears as a complete cylinder as seen in cross section . The presence of many overlapping leaf gaps produces a highly dissected stele, like a Dictyostele or a Eustele . The stems are usually subterranean .
Tree ferns are an example of the latter.
Branching is sporadic and may be dichotomous or lateral . There is little internodal elongation in most species, however there are viney types which are exceptions. Careful examination of tree fern stem will show that it is composed of leaf bases which are contiguous because there is No Internodal Elongation . This is an obvious limitation in an environment that contains angiosperms. The latter generally have lots of internodal elongation, and can quickly form a dominant canopy over slow-growing plants.