#Id: 10682

#XL - R Botany

Anomalous secondary growth

Several dicotyledons show secondary growth that is different from normal  secondary growth. The deviating methods of secondary thickening are called  abnormal or anomalous secondary growth. 

e.g., Bougainvillea (Dicot)

#Id: 10683

#XL - R Botany

Dicot stem anomalous secondary growth occurs due to following reasons:

Anomalous position of cambium 

e.g.,Serjania sp. and Bauhinia sp.

Abnormal behavior of normal cambium

e.g., Bignonia, Aristolochia, Tinospora, Clematis etc.

Extrastelar cambium formation

e.g., Amaranthus sp. 

Interxylary phloem or included phloem

e.g., Entada sp (box bean), Combretum sp (Combretum), Strychnos sp.

#Id: 10684

#XL - R Botany

#Id: 10685

#XL - R Botany

Secondary growth in monocotyledons

Due to lack of cambium in monocotyledons, secondary growth is absent. But Very few plants in monocots shows anomalous secondary growth such as Dracaena, Yucca, Aloe, Sansevieria and Agave

#Id: 10686

#XL - R Botany

Permanentt tissue

A) Simple Permanent Tissue

i) Parenchyma Cells

ii) Collenchyma Cells

iii) Sclerenchyma Cells

B) Complex permanent tissue

i) Xylem ( Hydrome)

ii) Phloem

#Id: 10687

#XL - R Botany

Parenchyma cells

Mature parenchyma cells have primary walls that are relatively thin and flexible, and most lack secondary walls

Mature parenchyma cells have a large central vacuole