Systematic significance of seed morphology and foliar anatomy among Acanthaceous taxa

The present study was aimed at investigating seed macro and micro-morphological and foliar epidermal anatomical characters of 15 Acanthus species from Pakistan. Firstly, plant specimens were collected and then identified on the basis of relevant references. For morphological analysis, seed characters were carefully examined using stereo microscopy and scanning microscopy to evaluate the usefulness of seed characteristics for the identification of systematic relationships. Considerable differences were found in seed coat morphology within studied taxa. Four types of seed surface pattern; striate (6 species), foveolate and papillate (2 species each), papillate rugose and rugose (one species each) were recognized. The dominant pattern of epicuticular projections was glabrous followed by prickles and bulges. Cell outlines were random and in rows while arrangement of cells was regular and irregular. For anatomical analysis, the foliar sections of leaves of each taxon were prepared, studied by light microscopy and then photographed by means of a Meiji affinity DK-5000 digital camera. Both adaxial and abaxial epidermis of the leaf has been studied and various micro-morphological characters examined including shape of epidermal cells, anticlinal wall pattern, lobes per cell, type of stomata and trichomes. Quantitatively, maximum epidermal cell length on adaxial and abaxial surface were observed in Dicliptera verticillata (Forssk.) C.Chr. (57.4 mu m) and (57 mu m) respectively. While stomata length was noted to be highest on abaxial side in Dicliptera verticillata (35.9 mu m). The micro-morphological features and foliar epidermal anatomy of studied Acanthus species showed many novel characters for accurate taxonomic identification and provide baseline information for plant taxonomists.

Automated summary

The present study investigated the seed macro and micro-morphological as well as foliar epidermal anatomical characters of 15 Acanthus species from Pakistan. The results revealed significant differences in seed coat morphology and highlighted the importance of foliar epidermal features for accurate taxonomic identification.