TOPIC ONE

CLASSIFICATION OF LIVING THINGS

Kingdom Plantae, Division Coniferophyta (Conifers)

General and Distinctive Features of the Division Coniferophyta Division Coniferophyta or the conifers belong to Kingdom Plantae. These plants are gymnosperms meaning non-flowering. They are non-flowering but seed bearing plants. They have vascular tissues. They are woody plants majority being evergreen trees. Few vanities are shrubs What are the general and distinctive features of the Division Coniferophyta?

General characteristics

• They have secondary growth whose thickening can be observed in cross section of @ stem

revealing annual rings, Secondary Growth is the result of growth Lateral Meristems (Vascular Cambiurn & Cork Cambium).

• Most of the members of Coniferaphyta live in cool climates where they form evergreen forests

They keep their leaves year-round.

• They have a large amount of intermodal elongation which allows them to grow faster than the

other higher plants,

• They are Xeromomphie, a characteristic that help (o protect them from exeessive loss of water and

therefore adept survival in extreme habitats

• Most are large trees while a few are shrubs and other small plants.
• Most of them have hard barks which protect inner softwood.

Distinetive characteristies

• Conifers are non-flowering but seed producing plants.
• They have seeds born in cones shaped structures rather than in fruits
• They are gymnosperms which mean naked-seed plants because they produce seeds in cones

rather than inside an embryo.

• The leaves are needlle-shaped and have a thick cuticle for protection and to decrease water loss

The Structure of Pinus

Pines are evergreen, coniferous resinous trees growing 34€“80 m tall. The bark of most pincs is thick and scaly. They have needle like leaves, Pines are among the most well- known coniferous trees in the world. They thrive in temperate ‘mountainous regions, but can also survive in tropical spots in the northern hemisphere. Pines live relatively long time than other coniferous plants, They may live between 100 and 1,000 years

• ‘The Stem:1he bark of most pines 1s thick and scaly. but some species have thin, flaking bark

The branches are produced in regular whorls appearing like a ring of branches arising from the same point

• Leaves:A cross-section of pine stem has several concentric rings with distinet horders between

each ring, The center of the stem is called pith, These rings are called annual rings because they grow seasonally and they help a plant to undergo secondary thickening Generally adult pines have needle-shaped leaves which are green and photosynthetic. The leaves are in bundles or clusters, ‘The leaves (cotyledons) on seedlings are bome in a whorl of 43€“24. Juvenile leaves, which follow immediately after seedlings, have single, green leaves arranged spirally on the

shoot. They also have non- photosynthetic scale leaves, similar to bud scales. They ate arranged spirally like the juvenile leaves

• Cones:A cone is an organ of pines that contains the reproductive structures. The woody cone is

the female cone, which produces seeds, The male cones, which produce pollen, are usually herbaceous and much less conspicuous. Explain the advantages and disadvantages of the Division Coniferophyta The advantages and disadvantages of the Division Coniferophyta The Advantages and Disadvantages of the Division Coniferophyta

Advantages of Conifers

• Conifers are very important for our economy because of their softwood, which is used for paper

and timber, as well as cedar which many people use for their homes because of its beauty and resistance to insects. They have a large economic use as softwood in furniture. In temperate and tropical regions, they are fast-growing softwoods that will allow harvesting in close succession

• Decoration and ceremony Many pine species make attractive omamentals. They are planted in

parks and larger gardens. Some varieties are suitable for smaller spaces, Pines are also commercially grown and harvested for Christmas trees.

• As medicine, Pines and eypress are rich in vitamin; their branches cones and oils can be

extracted and used as nutrient supplements

• Due to its soft texture conifers are widely used to manufacture Play wood.
• As other higher plants conifers are source of heat energy, used as firewood and charcoal
• ‘Thick forests of conifers form green belts that modi the climate
• Conifers form a large arena for Biological research Bcological studies
• Food uses Some species have large seeds, called pine nuts that are harvested and sold for

cooking and baking. The soft, moist, white inner bark (cambium) found clinging to the woody outer hark is edible and very high in vitamins A and CT ean be eaten raw in slices as a snack or dried and ground up into a powder for use as bread lour. Also White Pines are rich in Vitamin A and C; flour ean be made from the Pine tree's inner bark. By chewing bark of pine you can eliminate bad breath, Pines can reduce the pain of skin infections by applying warm pine sap.

Division Angiospermophyta ( Flowering Plants ) General and Distinetive Features of the Division Angiospermophyta Angiosperms are flowering plants under kingdom Plantae and division Angiospermophyta. This eroup of plants is sometimes called Magnoliophyta. Angiosperms are the most abundant land plants. Like gymnosperms, angiosperms are seed-producing plants but they are distinguished from gymnosperms by their characteristic of producing flowers. These plants produce fruits that

contain seeds instead of cones like itis in gymnosperms, The term angiosperm means a plant that produces seeds within fruits Angiosperms life eyele: The ovary has ovules that contain mega-sporocyte. Mega-sporophyte has four haploid megaspores; three megaspores disintegrate and the remaining one divides by mitotic divisions to produce eight nuclei in an embryo sac. The three nuclei are organized into the egg whereby one cell is the egg eell; the two others are ege helpers, Although these three

calls look are similar, only the egg cell continues to develop to an embryo sac. The embryo sac at this stage is the female gametophyte or mega-gametophyte. Pollination and fertilization: The pollen from the anther is transported to the stigma of a lower. In the stigma pollen tube emerges. ‘The mature male gametophyte therefore is @ germinated pollen grain, pollen tube and three sperm nuclei, The pollen tube grows downward

toward the ovary through the style and penetrates the embryo sac. After discharging its contents one of the sperm nuclei fuses with the egg nucleus and form a zygote, the other sperm fuses with the polar cell of the ovary, forming the endosperm nucleus. This is what 1s known as double fertilization, Fertilization in angiosperms begins very soon after pollination Note: In gymnosperms, fertilization can occur up to a year after pollination,

Double fertilization: Double fertilization is a distinctive characteristic of the angiosperms and results in 2 polyploid endosperm tissue, In double fetilization each ovule receives a pollen tube that delivers two sperm cells to the embryo sac. One sperm fertlizes the egg cell to form the diploid zygote, while the other sperm fertilizes the central polar cell to form triploid endosperm After double fertilization, the ovule develops into a seed and the ovary into a fruit.

General features of angiosperms They bear lowers which are reproductive structures. Fertilization takes place between make and female flower by pollination that includes insect pollination, wind poltination and animal pollination.

• Angiosperms have underground root as well as aerial shoot system.
• Angiosperms have very well-developed conducting tissues. ‘These tissues include the xylem and

the phloem arranged in form of vascular bundles.

• They have toot that helps absorption of water and minerals from the sol.
• Most of them have leaves that earry out photosynthesis, so they are autotrophs,
• They have alteration of generation, Sporophyte generation altemate with gametophyte

generation The sporophyte is the dominant, diploid stage and is the more visible form of the plant, with the leaves, stems, roots, and flowers. Gametophyte generation is reduced and it is found within the ovary and anther Distinctive features of angiosperms 1, The most obvious distinguishing feature of angiosperms is the possession of reproductive structures ealled Nowers

• They bear seeds enclosed in a earpel (the fruit), The seeds are the fertilized ovules
• They have endosperm produced after fertilization and before the zygote undergo its first division.

Endosperm has nourishing function, it nourishes the embryo,

• They have double fertilization whereby each ovule receives a pollen tube that delivers two sperm

cells to the embryo sae. One sperm fertlizes the egg cell to form the diploid zygote, while the other sperm fertilizes the eentral polar cell to form triploxd endosperm

• Their haploid gametophyte is confined inside the ovary (female) or anther (male) of the flower

unlike the free- living gametophytes of most other plants

• ‘They have conducting tissues phloem ond xylem. Unlike gymnosperms which have xylem

tracheid angiosperms has xylem vessels The Classes of the Division Angiospermophyta and their Distinctive Features Division Angiosperms is divided into two classes which are Monocotyledonae and Dicotyledonae, These two classes are distinguished from each other by their morphology and

Features of Class Monocotyledonac

1, Monocots have one cotyledon (or one seed leaf)

• Monocots have broad leaves with parallel venation
• Monocots have fibrous root systems.
• The floral parts in monocots occur in threes, or multiple of three. PMonocots lack cambium

secondary growth 5, Monocots have scattered vascular bundles in their stems. Typical example of monocot is a maize plant

Features of Class Dicotyledonae

• Dicots have two cotyledons (or two seed leaves),
• Dicots have net venation,
• Dicots have tap root system
• Dicots floral parts occur in fours and fives and multiple of four or five,
• Dicots have cambium secondary growth.
• Dicots have vascular bundles arranged into a ring. A Typical cxample of dicot is a bean plant

The Structure of Representative Plants Under Each Class (Monocotyledonae and Dicotyledonae)

Structure ofMonocotyledonae and Dicotyledonae plants

Monocatyledon (corn) Dicotyledan (bean) Seed coat Ses cook.

Reson Festburleoves Ho alyldons

‘Sle cotledon hethe Les sheath Endoseern 088 Fest true eaves Perael Tro ccbedors rot Shei Rank Lt sheath edo

Advantages and Disadvantages of Division Angiospermophyta

Advantages of Angiosperms

• Agriculture. Agnculture depends on angiosperms. Angiosperms provide human food. Example:

plants belonging to grass family (grains), are the most important food stocks. They include rice, maize, wheat, barley, millet, sugar cane and sorghum. Legume provides beans, several varieties ‘of nuts and soy. Also of potatoes, tomatoes, and peppers, pumpkins, melons and varieties of vegetables to include cabbage and lettuce. Many fruits ormges, lemons and grapefruits are angiosperms,

• Livestock, Plants belonging to grass family are the world number one feeds of livestock. Many

types of grassland in Affica are either grazed by cattle or wild animals. Also almost all feeds

consumed by human are also used by domestic animals as food.

• Wood. Angiosperms provide different varieties of wood for furniture, paper and building

materials. Carpentry and masonry depends largely on angiosperms for both soft and hard wood

• ‘Textile. Different varieties of fibers including cotton, flax, and hemp ate important raw materials

for textile industry. Cotton is the word first lass material for clothes,

• Medicine. Many organic drugs are coming fiom angiosperm herbs. They are either industrial

made or can be utilized in its raw form. Today it is believed that herbs form the best medicine when used in their fresh form than when industrial made

• Floriculture. Flowers from angiosperms have great social significance as they are used in

different kinds of ceremony, Roses for instance are the most sold flowers and they are highly purchased and used in wedding snd burial ceremonies

• Forestry. Forestry is the field of study whose base depends on both angiosperms and

gymnosperms, Many forests form green belts that habit different varieties of plants

• Ecology. Angiosperms provide a wide range of habitats for different species of organisms. They

also serve as primary producers of enerzy

• Climate, Angiosperms are used to modify climate, Green belts are established in order to absorb

carbon and reduce global warming

• Tourism. Many sites of tourism are plants oriented. Ecotourism for instance depends largely on

different plant species that host different kinds of land animals

Disadvantages of Angiosperms

• Toxins, Some plants are poisonous when eaten by human and other animals. They cause death to

human and other living organisms, Some cassava varieties are 2 good example. They have cyanide acid that inhibits cellular respiration,

• Drugs. Some angiosperm varieties are drugs that can be abused when taken Examples are

marijuana, cocaine, tobaceo and some caffeine varieties.

• Weeds. Some angiosperm varieties are bad weeds; they reduce crop yields, Some weeds are

parasites: Example, Cuscuta kilimanjari is parasitic to coffee plantations,