BIO 102 Angiosperm and Gymnosperms PDF

BIO102 General Biology2 DIVISION SPERMATOPHYTA (seed plant): GYMNOSPERM AND ANGIOSPERM Introduction to Seeded Plants (Spermatophytes)  Most of the plants we see around us are spermatophytes or seed plants, varying in size from trees and shrubs to small flowering plants like dandelion...

BIO102 General Biology2 DIVISION SPERMATOPHYTA (seed plant): GYMNOSPERM AND ANGIOSPERM Introduction to Seeded Plants (Spermatophytes)  Most of the plants we see around us are spermatophytes or seed plants, varying in size from trees and shrubs to small flowering plants like dandelions and grasses. They begin their life cycle as seeds produced either inside cones as in fir trees and pines, or inside flowers.  Seeded plants, or spermatophytes, are a major group within the plant kingdom that reproduce through seeds. They are characterized by the presence of seeds, which provide protection and nourishment to the developing embryo, allowing for more efficient reproduction and dispersal compared to non-seeded plants  The term higher plants is used for the group of plants that belong to the Division Spermatophyta.  These are plants characterized by the production of seeds.  The spermatophytes are the most highly developed in the plant kingdom. They are also the most highly evolved of all plants.  Spermatophytes produce seeds. The seed is a special structure employed for reproduction  The plant body is divided into leaf, stem and root  They are mostly trees, shrubs and some are herbaceous.  Spermatophytes are characterized by a phenomenon known as pollination, a process in their sexual reproduction. Hafsa Salihu SUB DIVISION OF SPERMATOPHYTA Two main groups of plants in the Division Spermatophyta are classed as higher plants. These are: Gymnosperms which belong to the Sub – division Gymnosperma and the Angiosperms which belong to the Sub- division Angiosperma. GYMNOSPERM Gymnosperms: These are seed-producing plants that do not form flowers or fruits. The seeds are often exposed on cones or other structures. The name Gymnosperm is derived from two Greek words:-“gymnos” which means “naked” and “sperma” which means “seed”. The name gymnosperm can therefore be interpreted to mean seed-bearing plants which produce their seeds in the naked form, that is, without being enclosed within pericarps. Classification Of Gymnosperm Gymnosperms are primarily classified into four main groups: Coniferophyta, Cycadophyta, Ginkgophyta and Gnetophyta. 1. Cycadophyta (Cycads) - Example: Sago palm (Cycas revoluta) 2. Ginkgophyta (Ginkgo): - Example: Ginkgo biloba (the only extant species) 3. Gnetophyta (Gnetophytes): - Examples: - Ephedra (used as a stimulant) - Gnetum (tropical vines) 4. Coniferophyta (Conifers): Examples: - Pine (Pinus spp.) - Spruce (Picea spp.) - Cedar (Cedrus spp.) Hafsa Salihu Characteristics of Gymnosperms 1. Seeds are typically naked, meaning they are not enclosed in an ovary. 2. Leaves are often needle-like or scale-like, adapted to conserve water. 3. Most gymnosperms are evergreen, retaining foliage year-round. 4. They reproduce via cones: male cones produce pollen, while female cones develop seeds. Importance of Gymnosperm -Ecological Importance: Conifers play a vital role in forest ecosystems, providing habitats and stabilizing soils. Economic Importance: Source of timber, resins, and compounds used in the pharmaceutical industry. Basically, gymnosperms are plants in which the ovules are not enclosed within the ovary wall, unlike the angiosperms. It remains exposed before and after fertilisation and before developing into a seed. The stem of gymnosperms can be branched or unbranched. The thick cuticle, needle-like leaves, and sunken stomata reduce the rate of water loss in these plants. Gymnosperms are found in boreal and temperate forests or deserts. Hafsa Salihu SUB DIVISION ANGIOSPERMS Angiosperms  These are flowering plants that produce seeds enclosed within a fruit. They are the most diverse group of plants in terms of species and form.  Angiosperms are vascular plants with stems, roots, and leaves. The seeds of the angiosperm are found in a flower.  These make up the majority of all plants on earth. The seeds develop inside the plant organs and form fruit. Hence, they are also known as flowering plants.  Angiosperms are the most advanced and beneficial group of plants. They can grow in various habitats as trees, herbs, shrubs, and bushes. Classification OF ANGIOSPERRM Angiosperms are primarily divided into two main groups based on their seed structure and flower type: Variations between monocots and dicots begin from the seed, which is the start of a plant‟s life cycle. Cotyledon refers to the „first seed leaf‟, present in the embryo. Known as cotyledon A cotyledon is the first leaf or one of the first leaves developed by the embryo of a seed plant that is usually folded within the seed until germination and serves as a storehouse of food. If it is a single seed leaf, then it is categorised as monocots and if it is a pair of leaves then it is categorised as dicots. MONOCOTYLEDON Monocotyledons commonly referred to as monocots are grass and grass-like flowering plants. few examples of monocotyledons are garlic, onions, wheat, corn and grass, etc.g., wheat, maize, rye, oats, rice, sorghum, bamboo and sugarcane Monocot plants are marked by seeds with a single cotyledon, parallel-veined leaves, scattered vascular bundles in the stem, the absence of a typical cambium, and an adventitious root system. Flower parts typically come in multiples of three, and the pollen grains characteristically feature a single aperture (or furrow). Hafsa Salihu They are economically the most important of all flowering plants because of their nutritious grains and soil-forming function, and they have the most-widespread distribution and the largest number of individuals. Grasses provide forage for grazing animals, shelter for wildlife, construction materials, furniture, utensils, and food for humans. Some species are grown as garden ornamentals, cultivated as turf for lawns and recreational areas, or used as cover plants for erosion control. Most grasses have round stems that are hollow between the joints, bladelike leaves, and extensively branching fibrous root systems. Importance of monocotyledon Food: Rice, Wheat, Corn, Sugarcane, and other staple crops. 2. Fiber: Cotton alternatives like Hemp and Sisal. 3. Biofuels: Ethanol from Corn and Sugarcane. 4. Timber: Bamboo and other monocot trees. 5. Ornamentals: Lilies, Orchids, and other decorative flowers *Environmental Importance:* 1. Soil Stabilization: Extensive root systems prevent erosion. 2. Water Filtration: Wetland monocots like Cattails filter water. 3. Wildlife Habitat: Grasslands and wetlands support diverse ecosystems. 4. Climate Regulation: Monocot forests influence local climate conditions. Hafsa Salihu DICOTYLEDON Dicotyledon or dicots are vascular plants that reproduce by the use of flowers whose seeds have two cotyledons or seed leaves. The seed has two embryonic leaves or cotyledons. Few examples of dicots are beans, cauliflower, apples and pear, etc Economic Importance: 1. Food: Beans, Peas, Lentils, Tomatoes, Potatoes, and many other edible crops. 2. Timber: Oak, Maple, Mahogany, Teak, and other valuable wood-producing trees. 3. Fiber: Cotton, Hemp, and Flax for textiles. 4. Medicines: Digitalis (Foxglove), Quinine (Cinchona), and many pharmaceuticals. 5. Ornamentals: Roses, Carnations, Chrysanthemums, and other decorative flowers Hafsa Salihu