In 1883, A.W. Eichler gave a system of classification for the whole plant kingdom. it is a traditional system as well as a phylogenetic system of classification of plants.
Eichler classified the plant kingdom into two sub-kingdoms. They are Cryptogamae and Phanerogamae.
(Gk. Kryptos=concealed; gamos=marriage)
The cryptogams are flowerless and seedless plants. They are simple plants like algae, mosses and ferns which do not produce flowers, fruits and seeds. Cryptogams are considered as lower plants.
Algae are chlorophyll bearing thallophytes. They are mostly aquatic occurring in fresh water and in sea. They exhibit autotrophic mode of nutrition.
Example: Chlorella, Chlamydomonas, Volvox, Cladophora, Zygnema, Sargassum, Gelidium, Polusiphonia, Spiulina, Laminaria.
Are the the simplest land plants with undifferentiated plant body. They are adapted to grow in water and on land. The more advanced forms only on land. Vascular tissues are absent.
Bryophyta is divided into three classes:
- Hepaticae-Liverworts eg: Riccia, Marchantia etc.
- Anthocerotae-Horn worts eg: Anthoceros
- Musci: Mosses eg: Funaria
Are most advanced cryptogams. Vascular tissues are present in the plant body. Therefore pteridophytes are also called vascular cryptogams. The plant body is differentiated into roots, stem and leaves. The ferns are a large group included under pteridophytes.
Pteridophyta is divide into four classes. They are the following
- Psilopsida- eg: Psilotum
- Lycopsida- eg: Lycopodium, Selag inella etc
- Sphenosida- eg: Equisetum
- Pteridopsida-eg: Nephrolepis, Pteris , Dryopteris etc.
Phanerogams are seed bearing plants. So they are also known as spermatophytes (Gk. Sperma=seed; phyton=plant). They are higher plants. The plant body is differentiated into roots, stem, and leaves with well developed vascular system.
Gymnospermes (Gk.gymno=naked; sperma=seed)
Are naked-seeded plants. The seeds are not enclosed in fruits. They do not produce flowers and they are regarded as primitive seed plants. They include mostly evergreen trees like conifers and cycads.
Gymnosperms are divided into three different classes. They are the following
- Cycadopsida-eg: Cycas
- Coniferopsida- eg: Pinus, Cedrus etc.
- Gnetopsida-eg: Gnetum
Angiosperms (Gk.angion=hidden; sperma=seed) are flowering and seed bearing plants. The seeds are enclosed in fruits. They form the dominant vegetation of the earth at present. They enrich the earth with unmatched beauty, colour and scent.
Angiosperm is divided into two classes.
- Dicotledons-eg: Pea, Sunflower, Mango tree
- Monocotledons-eg: Maize, Paddy, Musa, Coconut