| The family Polygonaceae distributes widely. It is cosmopolitan. Its consists of 13genera with 235 species and 37 varietas in China in Flora Reipublicae PopularisSinicae (Li A-R). It is divided into 2 subfamily: Subfam. Polygonoideae, Subfam.Rumicoideae. Subfam. Polygonoideae cludes Trib. Polygoneae and Trib.Atraphaxideae Damm. Trib.Rumiceae Damm belongs to Subfam. Rumicoideae.Trib.Polygoneae is segregated into 7 genera, e.g., Koenigia L., Polygonum L.,Antenoron Rafin., Pteroxygonum Damm. et Diels, Fagopyrum Mill., FallopiaAdans.and Reynoutria Houtt. Trib. Atraphaxideae Damm. consists of 3 genera:Parapteropyrum A. J. Li, Calligonum L. and Atraphaxis L.. Trib.Rumiceae isdivided into 3 genera: Rheum L., Rumex L. and Oxyria Hill. The familyPolygonaceae is studied in different ways. We know quite a lot about it, but eachauthor has as a rule treated the taxon only from one aspect or from several aspects buton a geographically restricted materil. Haraldson propose one circumscription ofthe family, it is quite a lot different from Flora Reipublicae Popularis Sinicae (Li A-R). The purpose of the present work is to make a critical evaluation of the anatomicalcharacters in Polygonaceae. And to select those characters found to be taxonomicallyuseful at sectional and generic levels. They are then together with nucleotide datamatrix, other relevant information mainly contributed by other authors, used for ataxonomic reorganization of Polygonaceae.11 species in 7 genera in Polygonaceae with the nucleotide variations of thechloroplast atpB-rbcL noneoding spacer are studied. They were sequenced for thesetwo species and other related representatives from the Polygonaceae. The atpB-rbcLspacer region varies among sampled species with a range from 753 to 902 bp;however, the great variation in this sequence provides enough information forevaluating the phylogenetic relationships of the two investigated species. In contrastto the current view, our phylogenetic analyses based on this data matrix suggested thatP. cyanandrum and P. forrestii nested within a well supported clade includingKoenigia islandica; the other three Polygonum species, however, clustered as theseparate clades with the other genera. These results suggest these two species shouldbe transferred to Koenigia from Polygonum. The resulting phylogeny is consistentwith the previous suggestions based on pollen and chromosome investigations. Thegeneric circumscription between Koenigia and Polygonum was further discussed according to these results in combination with gross morphology.Anatomical features of stems for 31 species in 13 genera in Polygonaceae arepresented, the results reveal that: (1) There were crystals in part of cells of cortex inPolygonum avicalare L, P. viscosum Buch.—Ham. Ex D. Don, P. lapathifolium L andAntenoron filiforme (Thunb.) Rob.& Vaut; (2) Xylem of Polygonum avicalare L,Calligonum junceum Litv, C cordatum E.Kor.ex N.Pavl, C. mongolicum Turcz,Atraphaxis bracteata A. Los, A. decipiens Jaub.et Spach, A. frutescens Ewersm. andParapteropyrum tibeticum A. J. Li was well developed, it reflects the adaptation todry environment; (3) Anatomical structure of Rheum australe D. Don is as similar asR. forrestii, Oxyria digyna (L.) Hill, O. sinensis Hemsel, Rumex crispus L., R.dentatus L. and R. japonicus Houtt. There was sclerenchyma around vascular bundles.There were lots of vascular bundles. The material can be divided into two maingroups due to collenchyma and sclerenchyma are continuous or not. That is to say, theContinuous-type and the Discontinuous-type. The Continuous-type is characterterizedby having continuous collenchyma or sclerenchyma. The anatomy of stem of this typeoccur in twelve species, Koenigia islandica L., P. viscosum Buch.-Ham. ex D. Don, P.lapathifolium L., P. hydropiper L., P. cyanandrum Diels, P. sibiricum Laxm., P.forrestii Diels, P. cathayanum A. J. Li, Fallopia aubertii (L. Henry) Holub, F.multiflora (Thunb) Harald., Reynoutria japonica Houtt., Antenoron filiforme (Thunb.)Rob.& Vaut. The Discontinuous-type is characterterized by having discontinuouscollenchyma or sclerenchyma. The anatomy of stem of this type occur in nineteenspecies, Polygonum avicalare L., Fagopyrum urophyllum, Fagopyrum dibotrys,Pteroxygonum giraldii, Calligonum junceum, C. cordatum, C. mongolicum,Atraphaxis decipiens, A. bracteata, A. frutescens (1.) Ewersm., Parapteropyrumtibeticum A. J. Li, Oxyria digyna, O. sinensis, Rumex hastatus, R. crispus, R.japonicus, R. dentatus, Rheum australe, R. forrestii Diels. The presemt results showthat the anatomical structures of stems in Polygonaceae is of important systematicvalue. The study is valuable to analysis species. It is obious that: (1) Oxyria Hill,Rumex L., Rheum L. are supported in Subfam. Rumicoideae Damm.. (2) It issupported that Calligonum L., Atraphaxis L., Pteroxygonum should be in Trib.Atraphaxideae Damm. (3) These results suggest that P. cyanandrum and P. forrestiishould be transferred to Koenigia from Polygonum. This study is useful to discussgeneric relationships.Our phylogenetic analyses not only based on this data matrix. Those anatomical chracters found to be taxonomically useful and other relevant information mainlycontributed by previous authors are also used to analyze the relationships amonggenera in Trib. Polygoneae, Trib. Atraphaxideae and Trib.Rumiceae. The resultstrongly support the close relationship between Koenigia and Antenoron;Pteroxygonum is more closely related to Fagopyrum than to Fallopia; Reynoutria,Fallopia are more closely related to Polygonum than to Koenigia; Atraphaxis may bethe most primitive genus in Trib. Atraphaxideae, Parapteropyrum is more closelyrelated to Calligonum than to Atraphaxis; Rheum appears to have the most primitivestructures, Rheum is more closely related to Rumex than to Oxyria. Polygonum s. lat.and Rumex have developed along different lines from a common origin. Atraphaxis ismost similar to the supposed ancestor.
|
PDF Full Text Request