Plant taxonomy deals with the identification, nomenclature, and classification of plants. Anatomy and cytology can provide information to aid plant taxonomy. Features of the epidermis, nodes, and chromosomes like size, morphology, and behavior during meiosis can help distinguish between plant groups and families. Cytological studies have shown close associations between certain families like Cyperaceae and Juncaceae based on shared chromosome traits. They have also supported taxonomic changes like transferring Yucca and Agave to Agavaceae or submerging Godetia into Clarkia based on shared chromosome numbers and structures.

4. Plant Taxonomy
• Plant Taxonomy is the branch of science which
deals with the identification, nomenclature and
classification of plants.
• Plant Taxonomy is the branch of science which
deals with the identification, nomenclature and
classification of plants.
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6. Anatomy in relation to plant taxonomyAnatomy in relation to plant taxonomy
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8. EpidermisEpidermis
• Shape, wall thickness, wall sculpturing and
inclusions in the epidermal cells.
• Papillate epidermal cells in Graminae
• Presence and distribution of silica bodies in
Cyperaceae
• Sclerification of the wall of epidermal cells in
some genera of Compositae
• Presence of very narrow epidermal cells in
Stylidiaceae
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9. Nodal anatomyNodal anatomy
• According to Dickison (1975) correlations of
nodal anatomy with some other features
might help significantly in tracing the
phylogeny of angiosperms
• Philipson (1968) attempted to use nodal
anatomy as an aid to taxonomy
• Sinnott(1914) considered the trilacunar node
as primitive and unilacunar and multilacunar
nodes as advanced.
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10. • According to Paliwal and Anand (1978) majority
of dicotyledons possess trilacunar nodes.
• Unilacunar nodes are found in Laurales,
caryphyllales, Ericales, Ebenales, Primulales,
Myrtales and a few Tubiflorae and Asteridae
members.
• Multilacunar nodes are found in Magnoliales,
Piperales, Trochodendrales, Umbellales and
Asterales.
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Nodal anatomyNodal anatomy

12. Cytology in relation to taxonomy or
Cytotaxonomy
Cytology in relation to taxonomy or
Cytotaxonomy
• The term karyotype is used for the phenotypic
appearance of the somatic chromosomes.
• The diagrammatic representation of karyotype is
termed as idiogram.
• The characteristics of the chromosomes, which
have proved to be of taxonomic value include
• Chromosome number
• Chromosome size
• Chromosome morphology
• Chromosome behavior during meiosis.
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13. Chromosome number
• Homoploids ( Pinus and Quercus, n=12
chromosomes )
• Polyploids (different species of Aster have n=9
or n=18 or n=27 )
• Euploidy
• Aneuploidy ( different species of Brassica bear
n=6,7,8,9, or 10 )
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14. Chromosome size
• 0.5 to 3 µ
• According to Stebbins (1938) the chromosome
size is characteristics of only certain groups
and families, and not related to phylogeny of
angiosperms.
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16. Chromosome Behavior at MeiosisChromosome Behavior at Meiosis
• Degree of sterility and occurrence of
hybridization are determined by the behavior
of chromosomes during meiosis
• Abnormalities in meiosis, such as non-pairing,
crossing over, unequal interchanges or
translocations, bridge formation, lagging
chromosomes etc. have all proved to be
systematic value.
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17. Systematic value of cytological studiesSystematic value of cytological studies
• Jackson (1971)
• Members of Cyperaceae and Juncaceae possess
chromosomes with diffuse or non-localized
centromere, and also show inverted meiosis. This
reflect a close association between these two families.
• Yucca had long been treated as a member of Liliaceae
because of superior ovary, and Agave of
Amaryllidaceae because of inferior ovary. Hutchinson
shifted both plants to Agavaceae because of the
presence of 25 small and 5 large chromosome in both
of them
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18. • On the basis of cytological studies, Lewis (1951)
submerged the genus Godetia in Clarkia
( Onagraceae)
• Naik (1977) differentiated three species of
Chlorophytum of Liliaceae on the basis of
cytological data. According to him C.bharuchae
has 2n=16 while C.glaucum and C. glaucoides
have 2n=42. both the later species having differ
karyomorphology.
• Warburg(1938) studied taxonomy of Gerniales
on the basis of cytological studies.
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Systematic value of cytological studiesSystematic value of cytological studies