3645. Vascular Bundle types. 16 Color Photomicrographs. 1. Psilotum, stem t.s. protostele 2. Lycopodium, stem t.s. actinostele 3. Pteridium, rhizome t.s. polystele 4. Osmunda, rhizome t.s. ectophloic siphonostele 5. Adiantum, rhizome t.s. amphiphloic siph