Description of a Typical Angiospermous Plant
A floral diagram provides information about the number of parts of a flower, their general structure, arrangement, and the relation they have with one another, cohesion and adhesion, position of the flower with respect to the mother axis. It is a ground plan of a flower. The calyx lays outermost, corolla next to calyx, androecium next to corolla and gynoecium in the centre.
In the floral formula
Br for bracteate
Brl for bracteolate
K stands for calyx
C for corolla
P for perianth
A for androecium and
G for gynoecium
Description of Some Important Families
Sub family: Leguminosae
There are about 452 genera and 7200 species in this family. They grow in tropical and sub-tropical regions.
Habit: Mostly herbs, shrubs, climbers, etc.
Roots: Presence of root nodules in which the symbiotic nitrogen-fixing bacteria (Rhizobium) are present.
Stem: weak and prostrate
Leaves: alternate, stipulate and dorsiventral.
Inflorescence: usually axillary or terminal raceme.
Flowers: bracteate, bisexual, zygomorphic.
Calyx: five, fused and aestivation is valvate
Corolla: petals 5, polypetalous, papilionaceous or vexillary aestivation
Androecium: 10 stamens,diadelphous (nine stamens are united to form a bundle and tenth stamen is free)
Gynoecium: Monocarpellary, unilocular with half-inferior ovary with marginal placentation
The family is a good source of proteins, oils, vegetables, timber and fibres. Pulses like red gram (Cajanus cajan), black gram (Phaseous mungo), green gram (Phaseous aureus), bengal gram (Cicer arietinum) are a rich source of proteins. Seeds of Pisum and Arachis are edible. Groundnut oil from Arachis hypogea seeds and soyabean oil from Glycine max are used in cooking. Fibre from Crotalaria is used to make ropes. Indigofera tinctoria yields blue dye.
Fig: Pisum sativum (pea plant) (a) Flowering Twig (b) Flower (c) Petals (d) Reproductive parts (e) L.S.of carpel (f) Floral Diagram and Floral formula
This family consists of about 85 genera and 2200 species. They are mostly herbs and some are shrubs. It is commonly called as potato family.
Root is of tap root system.
Stem is herbaceous covered by hairs or prickles.
Leaves are petiolote. Exstipulate with reticulate venation
Inflorescence is usually cymose. The flowers are braceteate, bisexual, pentamerous and hypogynous.
Calyx: 5 sepals, which are fused
Corolla: 5 petals and is gamopetalous with valvate aestivation
Androecium: has anther lobes, which are large, basifixed
Gynoecium: bicarpellary syncarpous superior ovary with swollen axile placentation
Stem tubers of Solanum tuberosum (Potato) are used as vegetables. Nicotiana tabacum is used to prepare cigars etc. Leaves of Solanum surattense and Datura are useful for curing asthma. Atropa contains alkaloid called 'atropine' which is used in making plasters.
Fig: Solanum nigrum Plant (a) Flowering Twig (b) Flower (c) L.S. of Flower (d) Stamens (e) Carpel (f) Floral Diagram and Floral Formula
Liliaceae (Monocot Family)
There are about 254 genera and 4075 species in this family.
Habit: Plants are mostly herbs, shrubs or trees.
Root: Fasciculated tuberous roots are present.
Stem: underground stem.
Leaves are alternate or whorled.
Inflorescence: racemose type or cymose or umbel
Flowers: bracteate, bisexual and hypogynous
Perianth tepals 6 arranged in two whorls of three each. The aestivation is valvate or imbricate.
Androecium: Stamens are six, arranged in two whorls of three each
Gynoecium: tricarpellary trilocular with many ovules and syncarpous
The bulbs of Allium cepa (onion) are edible. The cloves of Allium sativum (Garlic) are used as spice. The tuberous roots of Asparagus are edible. An important chemical mutagen 'colchicine' is obtained from the corms of Colchicum autumnale. 'Sarsaparilla' is a medicine obtained from the roots of Smilax.
Fig: Allium cepa (Onion Plant) (a) Complete Bulb (b) Inflorescence (c) Flower (d) Floral Diagram and Floral Formula