In this article we will discuss about Characters and Methods of Plant Identification.
Characters Considered Before Plant Identification:
i. Whether a plant is herbaceous or woody, and annual or perennial in nature.
ii. Whether or not milky or coloured sap is present in the leaf, stem or other plant parts.
iii. The leaf type, phyllotaxy, and venation.
iv. Presence or absence and type of stipule on young shoots.
v. The distribution and kinds of surface coverings (i.e. hairs, trichomes, spines, etc.).
vi. The parts of the flower and the number of sepals and petals, whether separate or fused, and also their arrangement i.e. aestivation.
vii. Whether perianth is present in one or more series, or absent.
viii. Whether pappus (e.g. Asteraceae) or epicalyx (e.g. Malvaceae) or similar structures are present.
ix. Whether a nectar-secreting disc is present in the flowers (e.g. Rutaceae).
x. Whether the flowers are actinomorphic or zygomorphic.
xi. The number and attachment of stamens and if there is any fusion of anthers or filaments.
xii. The number of pistils, styles and stigmas of the gynoecium, observation of a transverse section of the ovary, the number of locules, number of ovules per locule, and also the placentation.
xiii. The position of the ovary and fusion of the perianth by observing a longitudinally cut section of the entire flower through its centre.
Plant Identification Methods:
The methods of identification include the following:
(a) Expert Determination:
The best method of identification is expert determination in terms of reliability or accuracy. In general the experts have prepared treatments (monographs, revisions, synopses) of the group in question, and it is probable that the more recent floras or manuals include the expert’s concepts of taxa.
Experts are typically found in botanical gardens, herbaria, museums, colleges, universities, etc. However, although of great reliability, this method presents problems of requiring the valuable time of experts and creating delays for identification.
(b) Recognition:
It approaches expert determination in reliability. This is based on extensive, past experience of the identifier with the plant group in question. In some groups this is virtually impossible.
(c) Comparison:
A third method is by comparison of an unknown with named specimens, photographs, illustrations or descriptions. Although this is a reliable method, it may be very time consuming or virtually impossible due to the lack of suitable materials for comparison. The reliability is, of course, dependent on the accuracy and authenticity of the specimens, illustrations, or descriptions used in the comparison.
(d) The Use of Keys and Similar Devices (Synopses, Outlines, etc.):
This is by far the most widely used method and does not require the time, materials, or experience involved in comparison and recognition.