Jim Bidlack - BIO 5354/4354 PLANT ANATOMY Lecture 20 - Secondary Stem Growth I. Reasons and types of secondary stem growth A. Reasons for secondary growth in stems vs. roots 1. Method of satisfying the demand during growth (plumbing analogy) 2. systems 3. Greater herbage (topside) requires greater support B. Types of secondary growth 1. Continuous vascular cylinder (most common - angiosperms) a) Leftover procambium produces cells - becomes fascicular cambium b) Parenchyma between bundles becomes interfascicular cambium c) Both fascicular and interfascicular cambium produce secondary phloem and secondary xylem - they become or behave as a vascular cambium 2. Enlarging vascular bundles (less common - woody vines) a) Leftover procambium produces cells - becomes fascicular cambium b) Interfascicular cambium produces parenchyma to the inside and the outside c) Bundles remain separate d)
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