DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
Cells with the same structure and functionality constitute a tissue
Plants tissues are of two types:
- Meristematic tissue: cells divide actively
- Apical meristem– occurs at the tip and produces primary tissues, e.g. dermal, vascular and ground tissues
- Intercalary meristem– occurs in grasses between matured tissues
- Lateral meristem– produces secondary tissues, e.g. cambium
- Permanent tissue: cells, which don’t divide further after attaining their specialised structure and function
- Simple tissue: only one type of cells having the same structure and function
- Complex tissue: more than one type of cells that work in coordination
Epidermal Tissue System
It comprises the outer covering of the plants, such as epidermis, cuticle, stomata, epidermal extensions; trichomes in stem and root hairs. Stomata regulate gaseous exchange and water loss by transpiration. Guard cells are bean-shaped in dicots and contain chloroplasts. Grasses have a dumb-bell shaped guard cells. Root hairs are unicellular. Trichomes are multicellular
The ground Tissue System
They form the major bulk of tissues between epidermal and vascular tissues, e.g. cortex, pericycle, pith. It contains simple tissues.Mesophyll of leaves is a ground tissue with chloroplast.
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
The Vascular Tissue System
It consists of complex tissues of xylem and phloem.Dicots have cambium present between xylem and phloem of vascular bundle.Cambium forms secondary vascular tissues.Dicots have an open vascular bundle.Monocots have a closed type of vascular bundle, i.e. cambium is absent.Roots have a radial arrangement of vascular bundles, i.e. xylem and phloem are present alternatively.Stem and leaves have a conjoint arrangement of vascular bundles, i.e. xylem and phloem are present at the same radius.
Dicotyledonous Root
Epiblema is the outermost layer, which contains root hair.Several layers of cortex present, that ends with innermost layer endodermis , which contains waxy material called suberin forming Casparian strips.Next is pericycle, which gives rise to lateral roots and vascular cambium.Two to six vascular bundles are present.Radial and exarch vascular bundles.
Monocotyledonous Root
The structure is similar to dicot root but polyarch xylem bundles are present.Pith is large and no secondary growth
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
Dicotyledonous Stem
The outermost layer is the epidermis with cuticle.Trichomes and stomata may be present on the epidermis.The cortex consists of three layers; outermost hypodermis. (collenchymatous), middle parenchymatous cortical layer and the endodermis containing starch grains.Below endodermis, pericycle and radially located medullary rays are present.Vascular bundles are arranged as a ring.Vascular bundles conjoint, open and with endarch protoxylem.
Monocotyledonous Stem
Hypodermis is sclerenchymatous.
Vascular bundles are scattered, conjoint and closed.
Dicotyledonous Leaf
Also known as dorsiventral leaf due to distinct dorsal and ventral side.Reticulate venation.The epidermis covers both the upper and lower surface.There are more stomata present on the abaxial epidermis.Mesophyll cells are parenchymatous and perform photosynthesis.The mesophyll is made up of elongated palisade and oval or round spongy parenchyma cells.Vascular bundles are surrounded by bundle sheath cells and present on veins and mid-rib.
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
Monocotyledonous Leaf
Also known as isobilateral as both sides are similar.Parallel venation.Stomata are equally distributed on both sides.The mesophyll is not differentiated between palisade and spongy parenchyma cells.Some cells of the epidermis are modified to large cells called bulliform cells in grasses, they help in minimising water loss.Vascular bundles are of the same size.
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
Secondary Growth
Secondary growth is due to dividing lateral meristems; vascular and cork cambium.It is characterised by an increase in the thickness (girth).In the dicot stem, a ring of cambium is formed from intrafascicular cambium present between xylem and phloem and the medullary cells present adjoining the two vascular bundles that become meristematic.The cells, which cambium forms towards the periphery, form secondary phloem and form secondary xylem towards the pith.Cambium is very active during spring and forms earlywood or springwood, which has more xylary elements, light in colour and with low density.Latewood or autumn wood is formed during winters when cambium is less active. The autumn wood is dense and dark in colour.These form alternate light and dark annual rings, which help in predicting the age of the tree.
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
Heartwood is formed due to the deposition of tannins, raisins, oils and gums in the secondary xylem. It is hard, durable and resistant to insects.The peripheral region of secondary xylem conducts water and lighter in colour and known as sapwood.Cork cambium develops in the outer cortex region. It is also known as phellogen.Phellogen divides on both sides, differentiating into outer cells are called phellem or cork and the inner cells are known as phelloderm or secondary cortex.Suberin deposition the cell wall of cork makes it waterproof.All the tissue exterior to vascular cambium are called bark including secondary phloem.Lenticels present on the epidermis help in gaseous exchange.Secondary growth is absent in monocots but present in gymnosperms.
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
Table of Contents
Anatomy of flowering plants
1. Interfascicular cambium and cork cambium are formed due to (a) Cell division
(b) Cell differentiation
(c) Cells dedifferentiation
(d) Redifferentiation
Answer: C
2. Phellogen and phellem respectively denotes the
(a) Cork and cork cambium
(b) Cork cambium and cork
(c) Secondary cortex and cork
(d) Cork and secondary cortex
Answer: B
3. In which of the following pairs of parts of a flowering plant is epidermis absent?
(a) Root tip and shoot tip
(b) Shoot bud and floral bud
(c) Ovule and seed
(d) Petiole and pedicel
Answer: A
4. How many shoot apical meristems are likely to be present in a twig of a plant possessing 4 branches and 26 leaves?
(a) 26
(b) I
(c) 5
(d) 30
Answer: C
5. A piece of wood having no vessels (tracheae) must belong to
(a) Teak
(b) Mango
(c) Pine
(d) Palm
Answer: A
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
6. In conifers, the fibres are likely to be absent in
(a) Secondary phloem
(b) Secondary Xylem
(c) Primary phloem
(d) Leaves
Answer: B
7. When we peel the skin of a potato tuber, we remove
(a) Periderm
(b) Epidermis
(c) Cuticle
(d) Sapwood
Answer: A
8. A vesselless piece of stem possessing prominent sieve tubes would belong to
(a) Pinus
(b) Eucalyptus
(c) Grass
(d) Trochodendron
Answer: D
9. Which one of the following cell types always divides by anticlinal cell division?
(a) Fusiform initial cells
(b) Root cap
(c) Protoderm
(d) Phellogen
Answer: C
10. How many shoot apical meristems are likely to be present in a twig of a plant possessing 4 branches and 26 leaves?
(a) 26
(b) 1
(c) 5
(d) 30
Answer: C
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants
ALSO VISIT:
+2 BIOLOGY
DOWNLOAD MOBILE APPLICATION TO LEARN MORE: Anatomy of flowering plants