Structure of Ferns Ferns and fern-allies are more complicated in structure than most people would suspect. Their structures, though similar in some ways to those of flowering plants are different enough to warrant a distinctive terminology. The blade may be undivided to finely cut, each degree of division having a specific term. Blades more divided are designated as bipinnate or even tripinnate with some divided four or five times. The ultimate division are called pinnules.
Fronds arise from the rhizome.
In many cases the rhizome can be inconspicuous or even entirely underground. Rhizomes of tree ferns on the other hand may be 60cm in diameter and up to 12 m tall. The conducting tissue, known as the vascular bundle, carries the water, minerals, and nutrients throughout the plant. Roots Roots are formed from the rhizomes or sometimes from the Stipe. The roots usually do not divide once they grow from the rhizome.