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Title of Thesis
Taxonomic Studies of Grasses of Salt Range of Pakistan |
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Author(s)
Farooq Ahmed |
Institute/University/Department
Details
Department of Plant Sciences / Quaid-i-Azam
University, Islamabad |
Session
2010 |
Subject
Plant Taxonomy |
Number of Pages
378 |
Keywords (Extracted from title, table of contents and
abstract of thesis)
Stigma, Characters, Pakistan,
Taxonomic, Tribes, Grasses, Salt, Hemispherical, Vegetation, Range,
Species, Studies |
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Abstract
The research work
was conducted during May 2005-2009 in the taxonomy lab of
Quaid-i-Azam University Islamabad.The project involves the
morphological, palynological and anatomical studies of 66 species of
grasses belonging to 43 genera and 12 tribes within 4 sub families
collected from Salt Range of Pakistan. Paniceae is the largest tribe
having 10 genera and 22 species followed by Andropogoneae and
Eragrostideae with 10 and 6 genera and 13 and 8 species
respectively.Taxonomic studies of grasses are of prime importance
from systematic point of view and proved helpful in delimitation of
the taxa at the species, genus and tribe level. It is the first
time, that a comprehensive study of grasses of any area is conducted
from taxonomic point of view in Pakistan after Cope, (1982) who
classified the grasses from Pakistan on the basis of morphological
characters and in many species some characters are not examined
which are valuable taxonomically and has not mentioned, such as
shape, length and width of caryopsis and length of stigma and
anther.The objective of the study was to assess the potential of
grasses in the area and to identify and classify the grasses on the
basis of above mentioned studies and to study the differences among
the species of the same and different genera of the same tribe and
among the different tribes.
Morphological markers are helpful in the identification,
differentiation and classification of the species at species, genus
and tribe level.Variations in different morphological characters are
observed in different genera of the same tribe and among the species
of the same genus.There are few characters that are constant in the
different genera of the each tribe and are helpful in identification
and classification of the species to the tribe level. In the present
studies there are two new reports from the area.Tetrapogon
cenchriformis is identified by its spatheolate inflorescence while
Parapholis strigosa is identified by the length of anthers and
straight spikes. Previously only one species of Parapholis (P.
incurva) is reported from Pakistan, but the studies showed that
another species of Parapholis (P. strigosa) is also present in the
Salt Range of Pakistan. Quantitative characters of pollen are also
helpful in distinguishing different taxa. Maximum polar and
equatorial diameter is recorded in Bromeae followed by Andropogoneae
and Paniceae, while maximum polar diameter is also observed in tribe
Bromeae. Maximum exine thickness is shown by tribe Eragrostideae.
SEM of pollen showed four types of sculpturing patterns that are
scabrate, verrucate, rugulate and striate. Variations are also
observed in features regarding leaf epidermal and transverse section
studies at the species, genus and tribe level and by correlating
with morphological characters are valuable in the identification and
classification of different taxa. There are a few problematic
species that are identified and differentiated from the resembling
species by studying their anatomy. Pennisetum orientale is confused
with Cenchrus ciliaris, but it can be differentiated by the presence
of short cells with rounded papillae, which are absent in Cenchrus
species. Distinct type of microhairs with hemispherical distal cell
are found in genera of the all tribes belonging to subfamily
Chloridoideae, and bulliform cells make a girder to the abaxial side
that is the distinguishing character of this subfamily. In
Enneapogon persicus of tribe Pappophoreae special type of macrohairs
with narrow stalk cell are observed that are absent in other tribes
of subfamily chloridoideae making this tribe peculiar from other
tribes of subfamily Chloridoideae. In Andropogoneae and Paniceae, a
complexity in structure of silica bodies is seen and distal cell is
thin walled in bicellular microhairs which can be used as a tool in
identification. Bulliform cells are in fan shaped or irregular
groups. Most species belonging to tribes of subfamily Pooideae are
distinct in having long cells with straight walls, and length of
long cells is also recorded more in these tribes. Microhairs are
absent and subsidiary cells are mostly parallel sided and
chlorenchyma cells are diffused around the vascular bundles. There
are some species that are present in the area but not mentioned
previously during the vegetation study of the area due to improper
identification and collection from the area. It is concluded that
morphological, palynological and anatomical studies help in proper
identification and classification of grasses, and to classify the
previously identified vegetation of Pakistan.
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