Complex tissue types and it's elements . Xylem and phloem primary and secondary growth and it's differences. Xylem and phloem elements function and it's structure

1. Topic – Complex tissue

2. Tissue
Meristematic
tissue
Permanent
tissue
Simple tissue
Complex tissue
Secretory or special tissue

3. Xylem
1) Tracheids
2) Vessels / Trachea
3) Xylem fibres
4) Xylem parenchyma
Phloem
1) Sieve tube
2) Companion cell
3) Phloem fibres
4) Phloem parenchyma

5. Xylem Phloem
Function Vascular tissue that transport water
and dissolved nutrients from root to
the aerial parts of plants
Vascular tissue that transports prepared
food from the leaves and shoots to the
roots
Type Dead cell Living cell
Location Centre of vascular bundle The periphery of the vascular bundle
Cellular
Composition
Lignin , Cellulose Phloem sap
Structural
Composition
Tracheids ,Trachea , Xylem fibres ,
Xylem parenchyma
Sieve tube , companion cell , phloem fibres ,
phloem parenchyma
Movement
direction
Unidirectionally Bidirectionally
Support Forms the bulk of plants and provide
mechanical support
Forms a smaller parts pf plants and does
not provide any mechanical support
Differences between xylem and phloem

7. Differences between primary xylem and secondary xylem
Primary xylem Secondary xylem
Definition Primary xylem is the
xylem formed during the
primary growth by the
procambium
Secondary xylem is
the xylem formed
during the secondary
growth by the vascular
cambium
Occurrence Present in both
monocots and dicots
Seen only in dicots
Types of growth Primary growth Secondary growth
Meristem type Apical meristem Lateral meristem
Pit formation Not observed Observed
vessel Long and thin Short and wide
Tyloses Absent Present
Number of xylem fibres Less High

8. 4 types of cells found in xylem
Tracheids
Origin – Tracheids of primary xylem originated from procambium although
secondary xylem originated from vascular cambium.
Distribution –
❑ Pteridophytes and Gymnosperms – only Tracheids
❑ In Angiosperms –Tracheids and vessel both present
Function – Water and mineral conduction
Mechanical support to plants

9. Structure of tracheids

10. Vessels / Trachea
Origin and Development - vessels of primary xylem originated from procambium besides in
secondary xylem originated from cambium
Distribution - Pteridophytes and Gymnosperm – absent
Angiosperm – present ( exception – Amborella , Bubbia , Chlorenthus , Drimys etc.
Function – 1. Helps in conduction of water and minerals from the root to different parts of the
plants.
2. Mechanical support to the plants.

11. Structure of vessels / Trachea

12. Wood parenchyma - Parenchyama cells are only living cells in
the xylem . It’s main function is to storage
Wood fibres –
❑ The xylem fibres are non-living sclerenvhyma cells .
❑ These cells are found in between the trach and xylem vessels
of the xylem tissue
❑ Xylem fibres protect and provide mechanical support to the
major water conducting tissues of the xylem.

13. Phloem
Differences between primary phloem and secondary phloem
Primary phloem Secondary phloem
Develops from Procambium From vascular cambium
Bast fibres Absent Present
Types of growth Primary growth Secondary growth
Sclereids Absent Present
Occurrence Towards the periphery It is formed inner to the primary
phloem
Radial system Absent It is traversed by radial system of
phloem rays
Number of phloem
fibres
Less More
Number of sieve tube Less More

15. Companion cell –
1. Found in between sieve tube
2. Large nucleus , dense cytoplasm
3. Keep the sieve tube alive and provide nutrients
4. Contains many mitochondria ( provides energy for
translocation )
Phloem parenchyma –
1. Found in both primary and secondary phloem elements
2.These are found in dicot roots , leaves and stems but are
absent in monocot plants
3. Store food material like – resins, latex and mucilage
4. Helps in translocation of food