This study examines the patterns of morphological variation and phenetic relationships among 11 species of Senna Mill. from Bangladesh using 32 vegetative and floral characters. The highest similarity is found between S. obtusifolia and S. tora, while the highest variation is observed between S. alata and S. hirsuta. UPGMA tree derived from cluster analysis reveals three major clusters, the first of which consists of two species (S. alata and S. auriculata), the second cluster comprises four species (S. hirsuta, S. obtusifolia, S. tora and S. occidentalis) and the third one is composed of five species (S. multiglandulosa, S. sophera, S. siamea, S. timoriensis and S. surattensis). A close relationship is also found between S. multiglandulosa and S. sophera, and between S. siamea and S. timoriensis. Results obtained from the present study are found congruent with cytological and anatomical studies showing the significance of numerical analysis for taxonomic relationship in the genus Senna.DOI: http://dx.doi.org/10.3329/bjpt.v20i1.15467Bangladesh J. Plant Taxon. 20(1): 77-83, 2013 (June)

Phenetic analysis based on morphological characters is presented for 14 species of Desmodium Desv. in Bangladesh. This study examines patterns of morphological similarity and variation within Desmodium using 36 floral and vegetative characters. D. heterophyllum shows highest similarity with D. triflorum among the species employed. UPGMA dendrogram is constructed based on cluster analysis which reveals two major clusters, the first of which consists of seven species while the second cluster comprises six species, and D. microphyllum is found far from all other species. The presence of winged petioles distinguishes D. alatum and D. auriculatum from the other species. The present study shows the application of morphometric analysis for understanding the phenetic relationships among the species of Desmodium.

Desmodium pulchellum (L.) Benth. and D. triflorum (L.) DC. are two important medicinal plants of the family Fabaceae. D. pulchellum is a shrub, characterized by its finely grey-downy branches, ovate to oblong leaflets, narrowly triangular stipules, orbicular persistent bracts which conceals the flowers and fruits, white corolla, and short incurved style covered with appressed hairs. Its roots are used for burning sensations in the abdomen, flowers are used for dental caries and stem bark is given for head-ache (Jain, 1991). D. triflorum is a small herb, distinct by its prostrate or diffuse stem, obcordate, obovate or obtriangular chartaceous leaflets, purplish corolla with obovate standard petal, pubescent ovary and falcate pubescent pod. Leaves of this species are used as galactagogue, for the treatment of diarrhoea, dysentery and convulsions (Ghosal et al., 1972), and roots are effective in the treatment of asthma, bilious complaints and abscesses (Ghani, 2003).Seed germination is important to know the germination pattern of a plant, more particularly the medicinal ones that might need to bring under cultivation for the primary healthcare system. The significance of the seedling in plant population ecology has long been recognized (Silvertown and Lovett-Doust, 1993). The germination response pattern of seeds is also regarded as a key characteristic in plant life history strategy (Angevine and Chabot, 1979; Mayer and PoljakoffMayber, 1989). The variation in seed dormancy and the subsequent patterns of seedling emergence are controlled by environmental conditions. Important factors controlling the variation in seed dormancy within species include the environment of the mother plant during the time of seed maturation and environmental conditions after the seeds have been released (Liebst and Schneller, 2008). Certain environmental conditions may be required to break dormancy, and other conditions are often required to permit germination after dormancy is broken (Bewley, 1997). Seeds of many species require days, weeks, or months at low temperatures to break dormancy (Vleeshouwers et al., 1995), whereas others require warm temperatures for after-ripening to germinate when permissive conditions arrive (Baskin and Baskin, 1972).Many attempts have been made to investigate seed germination and seedling emergence of different annual and perennial species including medicinal plants (Baskin et al., 1993;Hassan and Fardous, 2003;Chauhan and Johnson, 2008;Liebst and Schneller, 2008;Liza et al., 2010). However, no study has surveyed germination patterns in Desmodium species in Bangladesh. Like many other important medicinal plants D. pulchellum and D. triflorum also need to bring under cultivation, but no work has been done so far in this direction. The aim of the present study is to investigate seed germination rate and level of dormancy of seeds in D. pulchellum and D. triflorum which might help in bringing the plants under cultivation.The mature seeds of Desmodium pulchellum and D. triflorum were collected from differen...