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The origin of the secondary plant body and the periderm. SPECIMENS TECHNIQUES :3, 7, 8, 9 *Bidens pilosa TS stem . Mature Helianthus stem *Chrysanthemum TS stem . *Helianthus TS root DEMONSTRATIONS :‑ . * Bougainvillaea TS stem . Beta vulgaris TS stem
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SPECIMENS TECHNIQUES :3, 7, 8, 9 • *Bidens pilosa TS stem. • Mature Helianthus stem • *Chrysanthemum TS stem. • *Helianthus TS root • DEMONSTRATIONS:‑ • . *Bougainvillaea TS stem • . Beta vulgaris TS stem • . *Prunus TS woody stem • . Beta TS root • . Quercus - two and four-year-old stem, TS
metaxylem protoxylem Chrysanthemum stem TS vascular bundle
starch sheath primary phloem fibres primary phloem sieve element companion cell secondary phloem vascular cambium secondary xylem metaxylem vessel metaxylem tracheids Chrysanthemum stem
epidermis outer cortex collenchymatous primary phloem fibers primary phloem fascicular cambium metaxylem protoxylem interfascicular cambium Helianthus TS young stem. end of primary growth
secondary growth is limited to a narrow band within the vascular bundle Helianthus: secondary growth
Sugar beet stem epidermis outer cortex: collenchyma cambium inner cortex: parenchyma starch sheath phloem Secondary xylem metaxylem The root protoxylem . included phloem px phloem Included bundle metaxylem mx protoxylem cambium In the root, these included bundles form new secondary vascular tissue, and grow anomalously Ground parenchyma ANOMALOUS GROWTH
vascular cambium, producing secondary phloem (exarch) and secondary xylem (endarch) Bougainvillaea shows anomalous secondary growth. Note primary vascular bundles embedded within the stele. Bougainvillaea stem
primary vascular bundle secondary xylem Bougainvillaea TS stem
secondary vascular bundle Sugar beet (Beta) root multiple cambia, secondary vascular bundles and embedded primary vascular bundles. This is an anomalous structure
Oak (Quercus) stem periderm secondary phloem fibers and sclerieds secondary phloem cambium primary ray secondary xylem
secondary phloem fibres lenticel Oak stem, Periderm and lenticels
primary ray companion cell secondary phloem vascular cambium secondary xylem The cambium, Quercus stem
secondary xylem formation is not continuous primary xylem Sunflower (Helianthus) root