The origin of the secondary plant body and the periderm
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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. *Prunus TS woody stem. Beta TS root. Quercus - two and four-year-old stem, TS
Chrysanthemum stemTS vascular bundle
protoxylem
metaxylem
Chrysanthemum stem
metaxylem vessel
metaxylem tracheids
secondary xylem
vascular cambium
secondary phloem
primary phloemsieve elementcompanion cell
starch sheath
primary phloem fibres
epidermis
outer cortex collenchymatous
primary phloem fibers
primary phloem
fascicular cambium
interfascicular cambium
Helianthus TS young stem. end of primary growth
metaxylem
protoxylem
Helianthus: secondary growth
secondary growth is limitedto a narrow band within the vascular bundle
Sugar beet stem
Included bundle
protoxylem
metaxylem
phloem
epidermis
outer cortex: collenchyma
starch sheath
Ground parenchyma
In the root, these included bundles form new secondary vascular tissue, and grow anomalously
phloem
metaxylem
protoxylem
The root
inner cortex: parenchyma
Secondary xylem
cambium
px
mx
cambium
.
ANOMALOUS GROWTH
included phloem
Bougainvillaea stem
vascular cambium, producingsecondary phloem (exarch) and secondary xylem (endarch)
Bougainvillaea shows anomalous secondary growth. Note primary vascular bundles embedded withinthe stele.
Bougainvillaea TS stem
primary vascular bundle
secondary xylem
Sugar beet (Beta) root
multiple cambia, secondary vascular bundles and embedded primary vascular bundles. This is an anomalous structure
secondaryvascular bundle
Oak (Quercus) stem
secondary xylem
secondary phloem
secondary phloemfibers and sclerieds
periderm
cambium
primary ray
Oak stem, Periderm and lenticels
lenticel
secondary phloem fibres
The cambium, Quercus stem
vascular cambium
secondary phloem
secondary xylem
companion cell
primary ray
Sunflower (Helianthus) root
primary xylem
secondary xylemformation is notcontinuous
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