Characters of Pteridophytes:
1 Pteridophytes are the first true land plants with xylem and phloem. Hence it is called vascular cryptogams.
2 Pteridophytes exhibit alternation of generation. The diploid sporophytic phase alternates with the haploid gametophytic phase.
3 The main plant body is sporophytes, which is the dominant phase, differentiated into true root, stem and leaves.
4. Sporophytes reproduce by means of spores. Spores are produced in sporangium.

There are three classes in Bryophyta. They are:
1. Class I - Hepaticae (Liverworts) eg: Riccia
2. Class II - Anthocerotae (Hornworts) eg. Anthoceros
3. Class III - Masci (Mosses) eg.Funtaria

Agar Agar:
1. Agar Agar is extracted from some red algae namely Gelidium, Gracillaria etc
2. which is used to prepare growth medium in laboratories.
Algae in space travel:
1. Chlorella pyrenoidosa is used in space travel to get rid of Co, and decompose human wastes
Single cell protein (SCP):
1. Some of the single cell algae and blue green algae are used to produce protein.
2. Eg: Chlorella, spirulina

Natural system of classification:
i) In this system plants are classified on the basis of their morphological and reproductive characters of the seeded plants.
ii) This classification is widely used in many Herbaria and botanical gardens all over the world.
iii) Eg: Bentham and Hooker's classification

(i) Acalypha indica:
1. Family - Euphorbiaceae
2. The paste obtained from the leaves is used to cure the burns on the skin.
3. The juice of this plant leaves is mixed with lemon juice to cure ringworm.
(ii) Aegle marmelos: (Vilyam)
1. Family - Rutaceae
2. Unripefruit is used to treat indigestion.
3. It is used to cure chronic, diarrhoea and dysentry.
(ii) Solanum trilobatum: (Theoduvalai)
1. Family - Solanaceae
2. Leaves and fruits of this plant cure cough and cold,
3. It is widely used in the treatment of tuberculosis and bronchial asthma.
(iv) Phyllanthus amarus:(Keechanelli)
1. Family - Euphorbiaceae
2. The entire plant is used for the treatment of jaundice.
3. It gives additional strength to human liver and used to treat other liver disorders
(v) Aloe vera: (Sothu Katrazhai)
1. Family - Liliaceae
2. Leaves of this plant is used to cure piles and inflammations on the skin.
3. It cures peptic ulcer.

i) Woods of many conifers are used in the paper industries Eg: pinus, Agathis.
ii) Conifers are the sources of softwood for construction, packing and plywood industry Eg: Cedrus, Agathis.
iii) Turpentine is an essential oil used for paint preparation extracted from the resin of pinus
iv) It is also used medicinally for relief from pain and bronchitis etc.
v) Seeds of Pinus gerardiana are edible.
vi) Ephedrine is an alkaloid extracted from Ephedra. It cures asthma and respiratory problem.
vii) Araicaroa bidwillii is an ornamental plant.