CHAPTER 5: MORPHOLOGY OF FLOWERING PLANTS
Seed – Plumule – stem
Radical – root
Types of roots Taproot, Fibrous root, Adventitious root.
Regions of root - Region of maturation
Region of elongation
Region of meristematic tissues.
Root cap
Modification of roots:
Storage- carrot, turnip
Prop root- banyan tree (support)
Stilt root – maize, sugarcane
Pneumatophores- rhizophora (mangroves)
The stem: Plumule have nodes and internodesbears with axillary /terminal buds
Modification of stems :
1. Storage - potato, ginger, tturmeric (perennation)
2. Tendrils – axillary buds –coils - support (watermelon)
3. Thorns - axillary buds – citrus (protection)
4. Flattened stem – opuntia (do photosynthesis)
5. Vegetative propagation (grass, jasmine, banana)
The leaf:
Short apical meristem gives rise to leaves arranged in acropetal order
Do photosynthesis
Three main parts are leaf base, petiole and lamina (leaf blade)
Have stipules
Leguminous petioles have pulvinus. (midrib)
Venation - arrangement of veins and veinlets on a leaf.
Types of venation :
Parallel- monocot leaves
Reticulate – dicot leaves
Types of leaves:
2. Simple leaves
3. Compound leaves - Pinnately compound (eg. Neem) and Palmately compound (eg. Silk
cotton)
Phyllotaxy: Pattern of arrangement of leaves on the stem /branch.
1. Alternate- china rose
2 Opposite- guava
3. Whorled- alstonia
Modification of leaves:
1. Tendrils - pea (support)
2. Spines - cacti (protection, water ioss)
3. Storage - onion/ garlic
4. Petiole leaves – acacia
5. Pitcher leaves – insectivorous plant (venus fly trap)
The inflorescence: Arrangement of flowers on the floral axis
Types of inflorescence: Depending on whether the apex gets converted in to a flower/continues to
grow there are two major types;
1. Racemose. Main axis continues to grow laterally (in an acropetal succession)
2. Cymose. Main axis terminates in a flower so limited growth (basipetal order)
The flower:
Four whorls. Sepal, petal, gynoecium, and androecium
Thalamus/receptacle
Trimerous/tetramerous/pentamerous/polymerous
Bracteates/ebracteate/bract. (Protective sheet around the flower)
Bisexual/unisexual
Actinomorphic (mustard ) zygomorphic ( pea ) asymmetric ( canna )
Based on the position of ovary:
1. Hypogynous ovary ( mustard ) superior
2. Perigynous ovary ( rose ) half inferior
3. Epigynous ovary ( guava, cucumber ) inferior
Parts of flower:
1. Calyx. Made of sepals. Can be gamosepalous/polysepalous
2. Corolla. Made of oetals. Gamopetalous/ polypetalous
Aestivation: Arrangement of sepals/ petals in floral bud
Main types are valvate (petunia alba , calotropis)
twisted(china rose ), imbricate( gulmohur) vexillary (pea, bean )
3. Androecium.
Staminode- sterile stamen
Epipetalous. Attached to the petal
Epiphyllous- attached to the perianth
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Polyadelphous- Free stamens
Monoadelphous- united as one bunch ( china rose )
Diadelphous – united two bundles ( pea )
Polyadelphous – many bundles ( citrus )
4. Gynoecium- one/ more carpels
Ovules attached on the wall of ovary called placenta.
Apocarpous - Free carpels ( lotus, rose )
Syncarpous - Carpels are fused (mustard, tomato )
After fertilization ovules devopls into seed.
Ovary develops into fruit
Placentation: Arrangement of ovules within the ovary.
Different types are marginal (pea), axile (china rose, lemon, tomato),
Parietal (mustard), freecentral (primrose) and basal (sunflower)
The fruit:
Parthenocarpic fruit: Formation of fruits without fertilization of ovary. Ex. Seedless grapes,
seedless orange.
Two parts of a fruit are pericarp and seeds.
Pericarp has epicarp, mesocarp and endocarp
Both mango and coconut are known as drupe fruits (fruits formed from single ovary /carpel)
Perianth: Fused petals and sepals.
The seed:
Fertilized ovules.
Made up of seed coat and an embryo
Embryo with radical and plumule with one cotyledon or two cotyledon
Structure of a dicot seed:
Seed coat, Testa and tegmen
Hilum - small pore (place where it is attached to fruit)
Micropyle. (water enters)
Endosperm, cotyledons, embryonal axis (plumule and radicle)
Mature seeds in dicot do not have endosperm called non-endospermic seeds. ( stored food is
utilized by embryo)
Structure of monocotyledonous seed:
Mostely endosperm except orchids
Endosperm is bulky and store food
Aleurone layer (produce enzymes to hydrolise proteins for embryo )
Cotyledon is scutellum
Protective coats- coleoptiles (piumule ), coleorhizae ( radical )
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Semi – technical description of a typical flowering plant:
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Floral formula by symbols:
Br - Bracteate _
K - Calyx G - Inferior ovary
C - Corolla
P- Perianth
A - Androecium
G - Gynoecium
G Superior Ovary
