The kingdom Plantae includes organisms that range in size from tiny mosses to giant trees.
Despite this enormous variation, all plants are multicellular and eukaryotic (i.e., each cell possesses a membrane-bound nucleus that contains the chromosomes).
Kingdom Plantae includes all the plants. They are eukaryotic, multicellular and autotrophic organisms. The plant cell contains a rigid cell wall. Plants have chloroplast and chlorophyll pigment, which is required for photosynthesis.
-Plants are multicellular, eukaryotic organism.
-Their cells have cell walls made of cellulose.
-Have chlorophyll, i.e. the green light trapping pigment.
-Plants manufacture their own food by the process of photosynthesis, i.e. plants are autotrophs.
-They reproduce both sexually and asexually.
Comparing animals, plants & fungi.
|-Cell wall made of chitin||-Cell wall made of cellulose||-No cell wall. Chitin found in insect skeleton|
|-store sugar in form of glycogen||– store starch||-store sugar in form of glycogen|
|-Chromosomes lack proteins||-Chromosomes have protein||-Chromosomes have protein|
|-cells have centrioles||-Cells lack centrioles||-Cells have centrioles|
|-Cell division-new cells by formation of new cell wall across the cell||-Cell division-new cells by formation of new cell wall across the cell||-Cell division-new cells by constriction of cell coating|
|-Reproduce by spores||-Reproduce by spores and gametes||-Reproduce by gametes (sperm & ova)|
|-Mitosis is completed within the nuclear membrane||-Nuclear membrane disappears during mitosis||-Nuclear membrane disappears during mitosis|
Economic importance of plants
1. Plants give out fresh air needed by animals, i.e. oxygen.
2. Plants produce soft wood for paper making.
3. They also produce hard wood for furniture and other construction and building purposes.
4. used as fuel e.g. charcoal and fire wood.
5. Act as wind breakers during strong winds.
6. Acts as cover crop to prevent soil erosion.
7. Are used to make medicine e.g. Neem tree( Mwarubaini) and pyrethrum.
8. Shelter and habitat for the wild animals.
9. As food for animals and human beings.
10. For beauty and decoration.
11. After death they decompose and add soil fertility.
12. Forest areas act as carbon sinks.
13. Forest areas act as water catchments areas.
14. Produce rubber for tyres.
15. Used in textile industries e.g. cotton
16. Some are used in cosmetic making and perfumes.
17. Some are used as stimulants, e.g. Heroin, Caffeine
Phylum or Division of plantae:
- Bryophyta eg: mosses, liverworts and hornworts.
- Pteridophyta eg: Ferns (seedless plant)
- Spermatophyta-seed bearing plants.
Eg: a: Gymnospermae class, e.g.: pines, conifers, Cyprus.
b: Angiospermae class: i. Monocotyledons, e.g.: maize
- dicotyledons, e.g. beans.
*For Bryophyta and Pteridophyta, check Form One Notes.
Gymnospermae or Coniferophyta (Conifers)
i. Seeds produced after fertilization are always naked,e. Not protected by the ovary.
ii. Leaves remain green through out the year, i.e. Needle like with thick waxy cuticle.
iii. Are cone bearing plants.
iv. Contain xylem and phloem.
v. They are seed bearing plants.
vi. Sexual reproduction is well defined.
vii. Almost all are terrestrial.
viii. Well defined system of roots, stem and leaves.
ix. Secondary thickening.
Examples are pine, cedar, juniper, cyperus, spruce, etc.
Demerits of Conifers
May shelter dangerous organisms that are dangerous to human being like snakes and wasps.
They do not produce fruits.
These include: –Herbs, i.e. small soft plants usually annuals or perennials.
–Shrubs, i.e. Small woody plants that live many years.
–Trees, i.e. Tall and large woody plants. Live many years.
i. All are flowering
ii. Majority are terrestrial.
iii. Fertilization is preceded by growth of the pollen tube.
iv. Seeds are protected by the ovary.
v. After fertilization the ovary matures into a fruit enclosing one or more seeds.
vi. They also produce asexually through vegetative propagation.
vii. Well developed system of root, stem and leaves.
viii. Vascular tissues (xylem and phloem) are present and well developed.
Demerits of angiosperm.
i. Some flowers are allergic to man, i.e. pollen grains can cause asthma.
ii. Some act as weeds, hence hindering growth of other plants.
iii. Potted plants in the house compete with man for oxygen. (so do not keep many flowers in the room at night.)
iv. Some are poisonous, i.e. pyrethrum, variety of cassava.
v. Some have thorns that can injure human and other animals.
Similarities between Angiosperm and Conifers.
-Both produce seeds.
-Both posses complex vascular bundles.
-Both are higher plants.
Differences between Angiosperm and Conifers
-Angiosperm are more beautiful hence used for decorations.
-Angiosperm have flowers while conifers have not.
-Angiosperm have fruits
-Angiosperm have covered seed while conifers have naked seed
The division has two classes:
- Monocotyledoneae: ie. Palms, Bamboo, Maize, wheat, sisal, sugarcane, millet, banana, lilies, orchid.
- Dicotyledoneae: ie. Beans, black jack, coffee, mangoes, jacaranda, eucalyptus.
Differences between Monocotyledoneae and dicotyledoneae.
| i. Vascular bundles small and scattered in the stem.
ii. Leaves are long and narrow.
iii. Leaves with parallel venation.
iv. Fibrous root system.
v. Embryo with one seed leaf or cotyledon.
vi. No pith in the stem.
vii. Floral parts in three or multiples of three.
viii. No Vascular cambium, i.e. No secondary growth.
| i. Vascular bundles arranged in a central cylinder.
ii. Broad leaves.
iii. Leaves with net like venation.
iv. Have tap root system.
v. Embryo with two cotyledons.
vi. Presence of pith in the stem.
vii. Floral parts in four or five or multiples of four or five.
viii. Vascular cambium is present in both roots and stems hence secondary growth.