Tribe Hyoscyameae Of The Solanaceae: Structure, Differentiation And Phylogenetic Relationship

The aim of this work is to have a better understanding of the structure,differentiation and phylogenetic relationship of the tribe Hyoscyameae in the Solanaceae using evidence from leaf epidermis,seed morphology,palynology,embryology,floral organogenesis,trnL-F and ITS sequences,and plant geography. The results are summarized as follows:1. Leaf epidermisLeaf epidermis of 21 species in seven genera of the tribe Hyoscyameae and four species in four related genera was investigated under both light microscope (LM) and scanning electron microscope (SEM). Stomatal apparatuses were found present on both upper and lower epidermis. They are mostly anomocytic,less often anisocytic. The epidermal cells are irregular,cross-like,suboblong or irregularly polygonal in shape. The anticlinal walls are rather straight,or sinuolate,sinuous and sinuate. The inner margin of the outer stomatal rim under SEM is nearly smooth,or sinuolate and sinuous. The cuticular membrane of epidermis under SEM is often striate,or simultaneously striate,granular and scaly,occasionally only granular and scaly,or even totally smooth. The type of stomatal apparatuses is a good character to distinguish between some genera,such as Hyoscyamus,Anisodus,Atropanthe and Atropa. In the 25 species examined,the epidermal cells fall into four types in terms of their shape and the pattern of the anticlinal walls. These types correlate to some extent with features of gross morphology,palynology and plant geography of the ten genera studied. Features of cuticular membrane can be used to differentiate clearly the two genera Physochlaina and Hyoscyamus,and some species within them. The cuticular membrane in the species of Physochlaina is simultaneously striate,granular and scaly,while only striate,or occasionally granular in the species of Hyoscyamus.2. Seed morpholoySeed morphology of 25 species in seven genera of the tribe Hyoscyameae and three related genera was investigated under SEM for the first time. The surface structure of the seeds is cerebelloid,or nearly so in Anisodus and Hyoscyamus pusillus,and reticulate in all the remaining genera and species. The testa cells fall into two types in terms of their shape and pattern of the cell walls. In one type the testa cells are from polygonal to suborbicular in shape,isometric,with the cell walls being nearly straight,and in the other the testa cells are irregular in shape,often not isometric,with the cell walls being variously sinuate. The appendages of the inner side of the cell walls of testa cells are rugose-sinuate,tuberculate,granular,laminar or spinulose in appearance. The size and shape of the seeds,and the position of the hilum are of no important systematic significance,but the protruding degree of the hilum,the shape of the testa cells and the pattern of their cell walls,particularly the appendages of the inner side,are of important value in the phylogenetic consideration of the tribe Hyoscyameae.3. PalynologyPollen grains of 23 species in seven genera of the tribe Hyoscyameae and threerelated genera were investigated under SEM. They are globose,subglobose,oblate and prolate in shape. The germination apertures are absent,or present and are irregularly poroid,3-colpate,4-colpate,3-4-colpate,pantocolpate and 3-colporate. The exine ornamentation is spinulose,tuberculate,variously striate,striate-foveolate,striate-reticulate,rugose-sinuate,minutely reticulate and reticulate. The colpal membrane is nearly smooth but with granular,spinulose or tuberculate protuberances. The pollen grains show great variations between the genera in the tribe Hyoscyameae in terms of the presence or absence of the germination aperture and its type,and the exine ornamentation,and thus can be used as important characters in the consideration of the phylogenetic relationship of this tribe. The evolutionary trend of the germination apertures of the pollen grains in this tribe may be from the absence of germination apertures to the presence of 3,4-colpate,then to 3-colporate germination aperture. Anisodus,whic...