Roots of Flowering Plants
* Roots provide proper anchorage to plants, synthesis plant growth regulators and help in the absorption of water and minerals from the soil.
* The primary root and its branches comprise the tap root system, which is mostly found in dicotyledonous plants.
* A quality certification scheme for food is being implemented under the ‘AGMARK’ quality control programme.
* The fibrous root system, usually seen in monocotyledonous plants, has a network of large and small roots originating from the base of the stem and spreading laterally.
* Adventitious roots arise from stems, leaves or parts other than the radical.
* From the tip upwards, a root has a root cap, a region of meristematic activity, a region of elongation and a region of maturation along with root hairs.
* The roots of certain plants modify themselves to perform specific functions like storing food, providing support and getting oxygen for respiration.
Stems of Flowering Plants
* A stem is a plant organ that develops from the plumule of a germinating seed and is the main axis or stalk of a plant.
* A node is a region from where leaves, flowers, branches or cones emerge, while an internode is the portion between two nodes.
* The stem along with its branches hold the leaves, buds, flowers and fruits.
* The stem transports water, minerals and photosynthates between the roots and the shoots.
* The stems of many plants get modified to perform functions like storing food, providing protection and support and aiding vegetative propagation.
Leaves of Flowering Plants
* A typical leaf has three main parts: leaf base, petiole and lamina.
* The leaf base attaches the leaf to the stem; the petiole helps the leaf to tilt in the direction of light, while the lamina is the expanded green portion of the leaf.
* The arrangement of veins and veinlets in a leaf blade or lamina is called venation.
* Based on the structure of the lamina, leaves are classified as simple and compound.
* Phyllotaxy is the pattern of arrangement of leaves on a stem or a branch.
* Leaves are sometimes modified ton perform functions like storing food, synthesising food, trapping and digesting food and providing support and protection.
Flowers
* A flower is the sexual reproductive unit of flowering plants or angiosperms.
* A flower has four main whorls: calyx, corolla, androecium and gynoecium, arranged on the thalamus or the receptacle.
* A bisexual flower has both androecium and gynoecium, while a unisexual flower has either androecium or gynoecium.
*Flowers can also be either asymmetrical or symmetrical based on the arrangement of the floral parts around the thalamus.
* Flowers are classified as trimerous, tetramerous or pentamerous based on the number of flowering parts such as sepals, petals and stamens.
* Flowers with bracts or reduced leaves at the base of the thalamus are called bracteates, while those without bracts are called ebracteate.
* Flowers are described as hypogynous, perigynous or epigynous based on the gynoecium with respect to the calyx, corolla and androecium.
* The arrangement of flowers on the floral axis is called inflorescence.
Parts of a flower
* A typical has four whorls: calyx, corolla, androecium and gynoecium.
* The outermost whorl is the calyx, which consists of seoals that protect the flower in its bud stage.
* The whorl inner to the calyx is the corolla, which consists of petals that attract insects and birds for pollination.
* The whorl inner to the corolla is the androecium, and it consists of stamens, which are the male reproductive organs of a flower.
* The innermost whorl is the gynoecium, and it consists of one or more carpels, which are the female reproductive organs of a flower.
The fruit and the seed
* Once fertilisation takes place in a flower, the ovary ripens to form the fruit, while the ovules form the seeds.
* A fruit, when formed without fertilisation of the ovary is called a parthenocarpic fruit.
* Typically, a fruit is made up of two parts-the pericarp and the seeds.
* A seed with two cotyledons is called dicotyledonous, and with a single cotyledon is called monocotyledonous.
* In some seeds, the developing embryo is surrounded by a nutritive tissue called the endosperm, which stores food and helps the embryo grow.
* Seeds with endosperm are called endospermic and those without are called nonendospermic.
Semi Technical Description of a Typical Flowering Plant
* The description of a typical flowering plant begins with its vegetative and floral characters and is followed by its floral formula and floral diagram.
* The floral formula and floral diagram represent the floral description in a condensed form.
* The floral formula is represented by a set of symbols.
* The floral diagram is a graphical representation of the cross-section of a flower and provides information about the different parts of a flower, their arrangement and the relationships between these parts.
Description of Important Flowering Families
* The description of typical flowering plant includes its vegetative characters, floral characters, floral formula and floral diagram.
* The Fabaceae family is a sub-family of the Leguminosae family.
* Plants belonging to the Fabaceae family can be trees, shrubs or herbs and are found all over the world.
* Plants belonging to the Solanaceae family, or the potato family, are found in the tropics, sub-tropics and temperate zones.
* Plants belonging to the Solanaceae family are usually herbs, shrubs and small trees.
* The Liliaceae family, or the lily family, is a characteristic representative of monocot plants.
* Plants belonging to the Liliaceae family are perennial herbs with underground bulbs, rhizomes or corms and are found all over the world.
