Proceedings Article | 22 May 2009
Proc. SPIE. 7378, Scanning Microscopy 2009
KEYWORDS: Microscopes, Soil science, Tissues, Microscopy, Diagnostics, Scanning electron microscopy, Humidity, Thin film coatings, Natural surfaces, Classification systems
SEM has greatly increased our knowledge of the microstructure of seeds. Mature seed coats are rather thick walled
and stable in a vacuum: this allows quick preparation for SEM examination, without the need of complicated
dehydration techniques. The low level of technical expenditure required, in combination with the high structural
diversity exhibited and the intuitive ability to understand the "three dimensional", often aesthetically appealing
micro-structures visualized, has turned seed-coat studies into a favorite tool of many taxonomists. We used dry
mature seeds of 26 species of 4 Leguminous genera, Acacia, Albizia, Cassia and Dalbergia to standardize a
procedure for identifying the seeds through SEM on the seed surface and seed sections. We cut transverse and
longitudinal sections of the seeds and observed the sections from different regions of seeds: midseed, near the
hilum and two distal ends. Light microscopy showed the color, texture, pleurograms, fissures and hilum at lower
magnification. The anatomical study with SEM on the seed sections revealed the size, shape, and number of tiers
and cellular organization of the epidermis, hypodermis, endosperm and internal structural details. We found the
ornamentation pattern of the seeds including undulations, reticulations and rugae that were species specific. Species
of Dalbergia (assamica, latifolia and sissoo), Albizia (odoratissima and procera), Acaia (arabica and catechu) and
Cassia (glauca, siamia and spectabilis) are difficult to distinguish externally, but SEM studies provided enough
characteristic features to distinguish from the other. This technique could be valuable in identifying seeds of
important plant species for conservation and trading.
