Biodiversity, Part- 2, Std-9

*Kingdom Plantae  
:- Overview of  features of kingdom Plantae.
-> They are made of eukaryotic cells.
-> They store carbohydrates such as starch.
-> Some plant cells ( except in some parasites) contain chloroplast.

* Classification of plants into different groups. 
:-> The plants can be classified at three
   levels.
1. Level one
:- Plant body ( Whether plant body has
  well-differentiated, distinct components).
2. Level two
:- Whether the differentiated plant body has special tissues(Xylem or Phloem ) for the transport of water and other substances within it.
3. Level three
:- Whether plants are able to bear seeds and whether seeds are enclosed within the fruits.
* Kingdom Plantae broadly classified into two sub kingdom. 
1. Sub-Kingdom Cryptogamae &
2. Sub-Kingdom Phanerogamae.

1. Sub-Kingdom Cryptogamae. 
:-  The term Cryptogamae derived from two Greek words- 'crypto'meaning hidden & 'gamous' meaning marriage.
:- They are also known as lower plants, flowerless or seedless plants.
:- They have hidden reproductive organs.
:- It is further divided into three divisions.
1. Division Thallophyta
:- This word has been derived from two Greek words 'thallos' meaning young shoot, 'phyton' meaning plant.
Features:-
1. Their body is not well-differentiated into
   roots, stems or leaves.
2. They do not have Vascular tissue system (Xylem & Phloem).
3. They mainly include algae.
4. They are predominantly aquatic.
E.g. Ulothrix, Ulva, Cladophora, Spirogyra, Chara, etc. 

2. Division Bryophyta
:-  This word has been derived from two Greek words- 'bryon' means moss &'phyton' means plant.
:- They are known as the Amphibians of the Plant kingdom.
Features:-
1. These are simplest land plants with no roots.
2. They do not have Vascular-Conducting tissues. Thus, they are called non-vascular crptogamic plants. 
3. They develop a number of hair-like structures at their lower end, known as rhizoids -> It helps in fixing plant in the soil and absorbing nutrients.
4. They are photosynthetic in nature.
5. They show alteration of generations, I.e
   Gametophyte and sporophyte.
6. Habitat- Mainly live in damp, shady
   places.
E.g. liverworts, hornworts, mosses, etc.

3. Division Pteridophyta
:- This word has been derived from two Greek words- 'pterid' meaning fern & 'phyton' means plant.
:- They are also known as vascular
  cryptogams.
Features
1. Their body is differentiated into true stem, leaves and roots like higher plants.
2. They have well developed vascular tissues I.e Xylem & phloem.
3. The most conspicuous pteridophytes are ferns.
4. Habitat - Humid tropical and temperate
   areas.
5. They do not produce seeds.
E.g. Marsilea, ferns, horse tails and club mosses.

* Sub-Kingdom Phanerogamae
:- Their body differentiated into true roots, stem and leaves.
:- They have well developed vascular                  tissues.
:- It is further divided into two sub divisions on the basis of presence or absence of fruits ( I.e seeds are naked or enclosed in fruits ).
*Gymnospermae, and 
*Angiospermae. 

1). Sub-division Gymnospermae
:- Derived from two Greek words- 'gymnos' meaning naked and 'sperma' meaning seeds.
Features:-
1. They are perennial woody plants forming either bushes or trees. Some of these are very large and live for thousands of years.
2. They have erect stem, may be branched in Pinus or unbranched as in Cycas.
3. Habitat:- cold areas where snowfall takes place.
4. They bear naked seeds.
5.  Their seeds contain food laden tissue called endosperm, for future growth of embryo.
E.g. Cycas, Pine, Ginkgo, Gnetum and 
    Araucaria, etc. 

2. Sub-division Angiospermae
:- Derived from two Greek words- 'angio' meaning covered and 'sperma' meaning seed.
:- They are better adapted to live on earth than any other plant.
Features:-
1. They are flowering plants whose seeds are enclosed in a fruit. ( After fertilization, ovary develops into fruit & ovule into seed).
2. They have also well developed vascular tissues I.e Xylem( contains vessels)& Phloem( contains companion cells).
E.g. Peas, Grams, Maize, Oats, Rice, Mango, Ipomoea, etc. 

Note:- On the basis of number of cotyledons ( seed ) Angiosperms are divided into Two groups.
a. Monocotyledonous or Monocot ( seeds with a single cotyledon known as monocot.
:- They have fibrous root & parallel venetion in their leaves.
e.g. Maize, Wheat, Rice, etc.
b. Dicotyledonous or Dicots ( Seeds with          two cotyledons known as dicots.
:- They have prominent tap root & reticulate
   Venetion in their leaves.
e.g. Pea, Gram, Pegion pea, etc.