- In dicot roots cork cambium originates in
(a) pith (b) hypodermis
(c) pericycle (d) endodermis.
- Differential divisions in various parts of RAM give rise to
(a) protoderm (b) procambium
(c) calyptrogen (d) all of these.
- Which of the following is a primary lateral meristem?
(a) Interfascicular cambium
(b) Intrafascicular cambium
(c) Cork cambium
(d) Phellogen
- During secondary growth in dicot root phellogen forms
_____ towards outer side.
(a) periderm
(b) secondary vascular tissue
(c) cork cambium
(d) phellem
- Spring wood is than autumn wood, ____ in colour
and in density.
(a) wider, lighter, lower
(b) narrower, lighter, lower
(c) wider, darker, higher
(d) narrower, darker, higher
6. Growth refers to
(a) reversible increase in size
(b) reversible increase in shape
(c) irreversible increase in size
(d) none of these.
7. Sapwood is
(a) outer functional wood of an old stem
(b) central non-functional wood of an old stem
(c) heavier and durable than heartwood
(d) comprised of dead cells only.
8. Cork cambium and vascular cambium are the examples of
(a) apical meristem (b) lateral meristem
(c) wound tissue (d) intercalary meristem.
9. Procambium, situated just behind apical meristem, gives
rise to
(a) vascular cambium (b) primary vascular bundle
(c) cork cambium (d) pith and endodermis.
10. Which of the following is not a characteristic of
meristematic tissue?
(a) Presence of prominent nucleus
(b) Presence of intercellular spaces
(c) Absence of vacuole
(d) Presence of proplastids
- What is the fate of primary phloem after secondary growth has occurred in a dicot stem?
- How does periderm formation take place in a dicot stem?
- What is the significance of periderm to a woody dicotyledonous plant?
Anomalous secondary growth
The term anomalous secondary growth is used to indicate the forms of cambial activity that deviate from that commonly found
in conifers and in woody dicotyledons of the temperate regions. It occurs in some arborescent monocots (e.g., Dracaena, Yucca,
Agave) and storage roots (e.g., beet, sweet potato). In arborescent monocot stems, a secondary cambium grows in hypodermal
region. The latter forms conjunctive tissue and patches of meristematic cells. The meristematic patches grow into secondary
vascular bundles. Amomalous vascular bundles also occur in cortex (cortical bundles, e.g., Nyctanthes) and pith (e.g., Boerhaavia).
In storage roots (e.g., beet), accessory cambial rings appear in the outside of endodermis. They produce less secondary xylem but
more secondary phloem. The secondary phloem contains abundant storage parenchyma.
