A Discussion On The Systematic Position Of The Genus Poona

Veronica,a genus of the family Scrophulariaceae,is characterized by herbs,opposite single leaf,racemes,calyx deep lobed,with 4 or 5 lobes,persistent style,capitate stigma,capsule with 2-lobed locularis.There are about 250 species,mainly distributed in the Eurasian continent.And there are 61 species throughout China,mainly grow in the southwest mountains in China.However,with the development of molecular biology and sequencing technology,using gene sequences for phylogenetic relationships determination has also emerged.By analyzing the sequences of two chloroplast genes and one ribosome gene,the Angiosperm Phylogeny Group(APG)has published 4 versions of APG system in Botanical Journal of the Linnean Society since 1998.It has broken the traditional classification system and aroused great attention and controversy in international plant taxonomy community.Its categories are massive,which are widely distributed.And its characters are widely changes and certain continuity,which brings great difficulty to classification and identification.The APG IV system has removed the genus Veronica from the family Scrophulariaceae to the Plantaginaceae,which caused the controversy of its systematic position,needs further discussion.In order to provide some new basis for the systematic position,determination of the genus Veronica,the leaf epidermal micro-morphology,seed shape and seed coat micro-morphology and cluster analysis were studied for some of the plants in the genus Veronica,Scrophularia,Plantago and Verbascum in this paper.The results are as follows:1.Leaf epidermis micro-morphologyThere are 21 species in 4 genera of the genus Veronica and its related plants were observed and studied by optical microscope,and the results are as follows: 1)The leaf epidermal cells irregular in shape in 4 genera,and it indicated that irregular shape cells were common characteristics.Except individual species,leaf epidermal cells of the genus Scrophularia and Veronica are irregular.But Plantago are predominant with irregular and polygonal,and both frequency nearly.Its showed that the leaf epidermal cells of the Scrophularia and Veronica were more similar and more closely related,which supported the classification of the genus Veronica to the family Scrophulariaceae;2)Irregular stomatal apparatuses were found in all 4 genera,indicating that irregular stomatal apparatuses showed commonness in 4 genera.The stomatal apparatus types of Scrophularia,Veronica and Verbascum thapsus were all irregular.And it were mainly irregular in Plantago,with horizontal stomatal apparatus appearing.This indicates that the similarities and relations between Scrophularia and Veronica are higher and closer,which supported the classification of Veronica to Scrophulariaceae.2.Seed shape and seed coat micro-morphologyThe morphology of seed of Veronica and its proximal plants were observed and studied with the aid of anatomical lens and scanning electron microscope,found that:1)The seeds of 3 genera are relatively small,with the length-width ratio between1.23-2.63.The shape is mainly ellipsoid,and the color is mostly dark brown and brown yellow.These characters are not regular in genera and cannot be used as the basis for classification among the 3 genera.2)The seed shape is mainly with fusiform,navicular and pleno-convex.Its showed that the shape of seeds were different among genera,groups and species.The seed shape of Sect.Omphalospora(V.polita,V.persica,V.biloba),Plantago minuta,P.virginica and P.aristata are all navicular.It is proved that Sect.Omphalospora(V.polita,V.persica,V.biloba)is more closely related to Plantago and support the treatment of APG IV.The seed shape of Scrophularia,Sect.Alsinebe(V.peregrina,V.arvensis),Sect.Beccabunga(V.anagallis-aquatica,V.undulata),Sect.Stenocarpon(V.ciliata)and Sect.Veronica(V.laxa)are all pleno-convex.This indicates that these groups of Veronica are more closely related to Scrophularia,which supported the classification of Veronica to Scrophulariaceae.The seed shape has some taxonomic significance among genera and groups of Veronica and its proximal plants.It is not supported that the genus Veronica is a natural group,and the groups within the genus are not consistent,some groups are similar to the Plantaginaceae,and some groups are similar to the Scrophulariaceae.3)According to the seed coat micro-morphological,18 species of Veronica and its proximal plants were divided into 6 types.The consistency of reticulate ornamentation among the 3 genera was high,indicating that the 3 genera were closely related to each other.With obvious differences,it could be used between groups and species.3.Cluster analysisWith the help of SPSS 26.0 and Excel,28 characters of 18 taxa of Veronica and its related plants were analyzed.With Pearson correlation as the measurement index,R-type cluster analysis was carried out for 28 traits,and Q-type cluster analysis was carried out for the traits with relatively high correlation.And it was found that Veronica was closely related to Scrophularia.Combining the statistical analysis and research of leaf epidermal micromorphology,seed shape,seed coat micro-morphology and cluster analysis,it was found that leaf epidermis cell micro-morphology,stomatal apparatus type,and seed solid shape could be used as the classification basis for Veronica and its proximal plants.The species coat ornamentation types showed obvious differences between groups and species,which could be used as the basis for classification between them.According to the results of cluster analysis,found that there was a close relationship between Veronica and Scrophularia.This study aims to provide some new morphological evidence for the systematic position determination of the genus Veronica.