Jim Bidlack - BIO 5354/4354 PLANT ANATOMY Lecture 15 - Stele and Bundle Types I. Types of steles (stellar types); stele refers to the central vascular network if the shoot and the root (includes outermost phloem and everything to the inside of it) A. Protostele 1. No pith and usually no separate vascular bundles 2. First pattern (phylogenetically) that appeared in vascular plants 3. Predominant pattern found in roots of almost all plants and shoots of lower vascular plants 4. Types of protostele a) Haplostele - xylem is a circular mass b) Actinostele - xylem margin is not smooth; it "undulates" c) Plectostele - xylem not one mass; series of plates B. Siphonostele 1. Has a pith and can have separate vascular bundles (primary growth) 2. More advanced plants 3. Found in shoots of seed plants and in roots having a broad stele (monocots) 4. Types of siphonostele a) Amphiphloic - phloem found on both sides of the xylem 1)
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