Page 5 - LN-ANATOMY OF FLOWERING PLANT

Based on pectinisation of the cell wall, there are three types of collenchyma
(a) Angular collenchyma
(b) Lamellar collenchyma
(c) Lacunar collenchyma
Different junctions performed by collenchyma are
(a) It provides mechanical support to the growing parts of the plant, such as young
stem and petiole of a leaf.
(b) Collenchyma cells are capable of photosynthesis, as they contain chloroplasts.
iii. Sderenchyma
The sderenchyma (Gr. Sclerous—hard; enchyma—an infusion) consists of long,
narrow cells with thick and lignified cells walls having a few or numerous pits.
The characteristic features ofsclerenchymatous cells are
(a) Cells are long or short, narrow, thick-walled and lignified.
(b) They possess hard and extremely thick secondary walls due to uniform
deposition of lignin.
(c) These are dead cells and do not perform any metabolic function.
(d) They show different types of lignin depositions and also have pits.

The sclerenchymatous cells may be divided into two types
(a) Sclereids These are short or irregular, spherical, oval or cylindrical
sclerenchymatous cells. The walls are very thick, irregular and the lumen is very
narrow. The walls show simple pits. These are commonly found in the fruit wall of
nuts, pulp of the fruits, like-guava, pear and sapota, seed coats of legumes and
leaves of tea.
(b) Sclerenchymatous Fibres These are thick-walled, elongated and pointed cells,
generally occurring in groups, in various parts of the plant.