This document discusses various chemical compounds that can be used for chemotaxonomic analysis of plants, including primary metabolites, secondary metabolites, and semantides. Primary metabolites like carbohydrates and amino acids are universally found but not very useful taxonomically. Secondary metabolites like phenolics, alkaloids, and terpenoids are more restricted in occurrence and greater importance for taxonomy. Specific examples of using flavonoids, monoterpenes, triterpenes, sesquiterpenes, and proteins in classifying and identifying plant species are provided.

1. BY
T.MITHRAA
2016601602

2.  Stable
 Unambiguous
 Not easily changeable
 Chemical data may be obtained from any part of the
plant
 Chemical information may be used for description or
identification of plants, or for establishing
relationships

3. (Kochaer, 1981)

4.  Raphides - crystals of calcium oxalate which are
present in large cells in different plant tissues
 They are long needle shaped crystals, pointed at
both ends and usually occur in bundles, thus being
easily identified.
 Observed in as many as 35 families of angiosperms.
 Several families of the Order Centrospermae and
the Family Cactaceae show the presence of
raphides

5. ovary of Lachenalia bulbifera
Liriope platyphylla
tepals of Conanthera campanulata

6. Chemical compounds
Primary
metabolites
Secondary
metabolites
Semantides

7.  Molecules involved in vital metabolic pathways.
 Universal occurrence
 Not very significant in chemotaxonomy
 Eg: Sugar containing carbohydrate ‘sedoheptulose' is
stored in large quantities as a reserve food in the
genus Sedum
 Amino acids

8.  Secondary plant products are those macromolecules
that lack nitrogen
 Restricted occurrence
 Greater taxonomic importance
 Includes different kinds of compounds such as
phenolics, alkaloids, terpenoids, etc.
 They are usually not involved in vital functions and
are largely storage products or pigments.

9.  Flavonoids – Phenolic compounds of leaves
 Monocots & Dicots
 Structural variability and chemical stability
besides widespread distribution.
 Rapid and easy identification

10.  80 species of plants from the family Ulmaceae
 A majority of the species contain flavonols, but a few
species have glyco-flavonols.
 These two types of flavonoid compounds are never
present together in any species.
 Ulmaceae is divided into two subfamilies called
Ulmoideae and Celtoideae
 Family Ulmaceae characterised by the presence of
flavonols, and family Celtaceae. characterised by the
presence of glyco-flavonols
(Ciannasi ,1978).

12.  In the genus Salvia, 19 species could be
distinctly identified and classified on the
basis of their monoterpenes
 Triterpenes and sesquiterpenes were useful
in the classification of the families
Cucurbitaceae and Compositae (Asteraceae),
respectively

13.  DNA (primary semantide)
 RNA (secondary semantide)
 Proteins (tertiary semantide) - most favoured
Electrophoresis - storage proteins of tetraploid wheat,
Triticum dicoccum and the diploid grass Aegilops
Squarrosa
Serological analysis - different amount of serological
activity in members of different plant families may be
interpreted as a reflection of the evolutionary
differences in the primary structure of the proteins
Several tuber-producing species of Solanum were studied
to understand the evolution of the cultivated potato
Solanum tuberosum (Hawks, 1960)

14.  Betalains – nitrogeneous anthocyanins
 Steriods
 Iridoid compounds – Monoterpenoid cyclopentanoid
lectones
 Alkaloids - nitrogen containing organic compounds with
a heterocyclic ring
 Glucosinolates – mustard oil glucosides
 Lipids and waxes
 Cyanogenic compounds