Pterophyta-5

The Stele Varies Greatly and ranges from a Protostele to Siphonostele to a highly dissected Dictyostele. in some cases it seems like more than one type of stele is present simultaneously. This condition is called a Polystele.

Careful studies have shown that the complexity of the vasculature in the stem is related to the complexity of Phyllome.

An Endodermis is present.

Ectophloic Siphonostele

Amphiphloic Siphonostele of Dickinsonia

Dictyostele

The Stem Cortex contains Parenchyma and Sclerenchyma. Sclerenchyma is usually Lignified.

Chlorenchyma can occur but since most photosynthesis occurs in the large leaves, stem chlorenchyma contributes little to the overall carbon fixation.

The Epidermis has a Cuticle and Scales.

Epidremis & Cortex of a fern Stem. The Blue-Green color indicates Lignin. Note the thick walls and degree of lignification of the outermost cells in the Cortex and Epidermis

Cuticle Stained with Sudan Red

Pterophyta - 5

The Stele Varies Greatly and ranges from a Protostele to Siphonostele to a highly dissected Dictyostele. in some cases it seems like more than one type of stele is present simultaneously. This condition is called a Polystele.

An Endodermis is present.

The Xylem is composed of Tracheids.

Phloem is composed of Sieve Cells

The Stem Cortex contains Parenchyma and Sclerenchyma. Sclerenchyma is usually Lignified.

Chlorenchyma can occur but since most photosynthesis occurs in the large leaves, stem chlorenchyma contributes little to the overall carbon fixation.

The Epidermis has a Cuticle and Scales.