1. Different systems of classification for vegetable drugs

2. Medicinal drugs can be arranged under the following headings
1- Alphabetical
Either use Latin or Vernacular name
This arrangement is employed only for dictionaries
Gives no indication about inter-relationship

3. 2- Taxonomic
Drugs are arranged according to plants from which they are obtained
Classes, orders, families, genera and species
e.g drugs from plants like
Square stem, opposite leaves and bilabiate flowers (peppermint, thyme) are considered from Labiatae

4. 3-Morphological 1- Organized drugs 2- Un-organized drugs
Drugs are divided into groups
1- Organized drugs
Leaves, flowers, fruits, seeds, herbs entire organisms, woods, barks, rhizomes and roots.
2- Un-organized drugs
Extracts, gums, resins, oils, fats and waxes.

5. 4-Therapeutic or pharmacological
R.Pratt and H.W.Youngken (1956)
Drugs are employed for their therapeutic effects, method of study called therapeutic classification.
e.g. senna, castor oil are considered because of their action on intestinal tract.
So this type of consideration forms the basis for science of pharmacology.

6. 5-Chemical or biogenetic
Constituents e.g alkaloids, glycosides, volatile oils etc.
Their biosynthetic pathway forms the basis of classification.
Some drugs contain constituents which are therapeutically active, some only chemically active.
Certain plant families exhibit definite type of chemical principles

7. Chemical classification
Solanaceae contain alkaloids (atropine, scopolamine)
Umbiliferae contains volatile oils
In a like manner, drugs containing volatile oils, or resins, or tannins, or glycosides can be classified in their perspective phytochemical groups.

8. Questions/Suggestions