Fin-winged fruits have two or more wings aligned with the longitudinal axis like the feathers of an arrow, as exemplified by Combretum, Halesia, and Ptelea. Such fruits vary in dispersal mode from those in which the fruit itself is the ultimate disseminule, to schizocarps dispersing two or more mericarps, to capsules releasing multiple seeds. At least 45 families and more than 140 genera are known to possess fin-winged fruits. We present an inventory of these taxa and describe their morphological characters as an aid for the identification and phylogenetic assessment of fossil and extant genera. Such fruits are most prevalent among Eudicots, but occur occasionally in Magnoliids (Hernandiaceae: Illigera) and Monocots (Burmannia, Dioscorea, Herreria). Although convergent in general form, fin-winged fruits of different genera can be distinguished by details of the wing number, texture, shape and venation, along with characters of persistent floral parts and dehiscence mode. Families having genera with fin-winged fruits and epigynous perianth include Aizoaceae, Apiaceae, Araliaceae, Asteraceae, Begoniaceae, Burmanniaceae, Combretaceae, Cucurbitaceae, Dioscoreaceae, Haloragaceae, Lecythidiaceae, Lophopyxidaceae, Loranthaceae, and Styracaceae. Families with genera having fin-winged fruits and hypogynous perianth include Achariaceae, Brassicaceae, Burseraceae, Celastraceae, Cunoniaceae, Cyrillaceae, Fabaceae, Malvaceae, Melianthaceae, Nyctaginaceae, Pedaliaceae, Polygalaceae, Phyllanthaceae, Polygonaceae, Rhamnaceae, Salicaceae sl, Sapindaceae, Simaroubaceae, Trigoniaceae, and Zygophyllaceae. This survey has facilitated the identification of fossil winged fruits such as Combretaceae and Araliaceae in the late Cretaceous of western North America and provides additional evidence toward the identification of various Cenozoic fossils including Brassicaceae, Fabaceae, Polygonaceae, Rutaceae, and Sapindaceae.

Phylogenetic Distribution and Identification of Fin-winged Fruits

The Polygonaceae (40-50 genera and approximately 1,100 species) are characterized by the presence of an ocrea, an hyaline or membranous tubular sheath, derived from the fusion of the stipules. Their classifi cation is based principally on macromorphological characters. The broad Poly- gonum s.l. is a much debated genus which has been variously interpreted in the literature: its relation to associated genera is not clear and moreover, it has been subdivided into numerous more natural taxa considered at the rank of genus, subgenus or section. In the present study, using analysis of the rbcL sequence the monophyly of the various taxa that Polygonum s.l. has been subdivided are investigated by focusing on the species present in Europe in order to reach a classifi cation more in line with the molecular data. The phylogenetic tree obtained with the maximum parsimony method confi rms that Polygona- ceae is monophyletic, however, the subfamily Polygonoideae seems to be paraphyletic as it includes the Eriogonoideae. On the basis of the principal clades identifi ed the restriction of the Polygonoideae to only those taxa with an herbaceous habit is confi rmed and a new classifi cation articulated in 4 tribes is proposed: 1) Polygoneae, subdivided into Polygoninae (Atraphaxis, Polygonum -incl. Polygonella- and, probably, Calligonum, Oxygonum, Parapteropyrum and Pteropyrum) and Reynoutriinae (Fal- lopia, Homalocladium, Muehlenbeckia, ×Reyllopia, Reynoutria) as well as an incertae sedis genus (Knorringia); 2) Persicarieae, subdivided into Persicariinae subtrib. nov. (Persicaria) and Koenigii- nae (Aconogonum, Bistorta, Koenigia, Rubrivena); 3) Fagopyreae (Fagopyrum, Harpagocarpus and, probably, Eskemukerjea and Pteroxygonum); 4) Rumiceae (Emex, Oxyria, Rheum, Rumex). Lastly new combinations and/or new names are proposed in the genus ×Reyllopia, Persicaria and Rubrivena.

Molecular phylogeny of Polygonum L. s.l. (Polygonoideae, Polygonaceae), focusing on European taxa: preliminary results and systematic considerations based on rbcL plastidial sequence data

This study represents phylogenetic analyses of two woody polygonaceous genera Calligonum and Pteropyrum using both chloroplast fragment (trnL-F) and the nuclear ribosomal internal transcribed spacer (nrDNA ITS) sequence data. All inferred phylogenies using parsimony and Bayesian methods showed that Calligonum and Pteropyrum are both monophyletic and closely related taxa. They have no affinity with Atraphaxis, instead allied with a clade in which the genus is nested. Infrageneric relationships in Calligonum, due to the paucity of informative

http://www.ijbiotech.com/article_7122_8bd56f575495dae5615f19f45213c9de.pdf

The phylogeny of Calligonum and Pteropyrum (Polygonaceae) based on nuclear ribosomal DNA ITS and chloroplast trnL-F sequences

Chromosomal data are important for elucidating intergeneric relationships and delimitating infrafamiliar tribes in plants. In this study, we firstly reported karyological data of two genera of the Atraphaxideae in the Polygonaceae: Parapteropyrum and Atraphaxis. The former is a monotypic genus and occurs only in southwest Tibet while the latter with about 20 species is widely distributed in the dry habitats of central Asia. The chromosome number and karyotype of P. tibeticum are formulated as 2n = 48 = 16m + 16sm + 16st, belonging to 2B type. Both A. manshurica and A. bracteata have the same chromosome number of 2n = 22 and similar karyotypes (22m, belonging to 1A). The basic chromosome number of another genus (Calligonum) of the Atraphaxideae is x = 9. Because the basic chromosome numbers of these three genera are different, suggesting that aneuploid evolution may have played an important role in the early diversification of the Atraphaxideae or this tribe is not monophyletic. The origin of the ...

http://www.caryologia.unifi.it/past_volumes/62_4/01-1529.pdf

Karyological studies of Parapteropyrum and Atraphaxis (Polygonaceae)

The Euphorbiaceae are notable for floral diversity and evolutionary complexity. Croton is the second largest genus in the family and exhibits particular diversity in its flowers. The aim of this study was to investigate the floral ontogeny and structure of three Croton species with distinct morphologies, with a focus on testing the hypothesis that the filaments of female flowers, which have received different interpretations in the literature and are currently described as reduced petals, are staminodes and part of a vestigial androecium. With the ontogenetic study we can understand the origin of the organs and associate these with flower evolution in the genus. Flowers in several stages of development were analysed using light microscopy and scanning electron microscopy. In the early stage of development, the sepals are the first structures to be formed, although they do not continue to grow in female Croton fuscescens Spreng. flowers. Petals are absent in female flowers, with filamentous, petaloid structures, interpreted here as staminodes, alternating with the sepals in Croton lundianus (Didr.) Mull. Arg. In Croton sphaerogynus Baill., the staminodes are located between the nectary lobes. The stamens exhibit centripetal development in the flower bud stage, and the carpels are post-genitally connate, with differences in style branching. Besides the ontogenetic interpretation for the filamentous structures, the genus shows transitional structures that we consider evolutionary reductions. Our results can explain how developmental alterations have influenced the suppression and modification of floral organs in the genus.

Flower development in species of Croton (Euphorbiaceae) and its implications for floral morphological diversity in the genus

Gross morphology, fruit anatomy, tepal venation, pollen morphology, chromosome number and ITS sequence of Pteroxygonum Damm. & Diels as well as other related genera (Polygonum, Fallopia, Reynoutria, Fagopyrum, and Antenoron) have been investigated to evaluate the generic status of Pteroxygonum. Pt. giraldii Damm. & Diels has three sharp horns at the base of fruit, which is distinctive among all the genera investigated. Upon observation of fruits under a light microscope (LM), the exocarp of Pt. giraldii is usually thickened and delimited by the rectangular cells with some sporadic undulating lumen, while that of Fagopyrum is thin-walled and isodiametric to rectangular in the cell shape. Analysis of tepal venation was performed under a stereomicro- scope, and two types of tepal venation were found in Fagopyrum and Pteroxygonum. The type I is trifid, observed in Pt. giraldii, F. esculentum Moench, F. dibotrys (D. Don) Hara and F. tataricum (L.) Gaertn. The type II, found in F. caudatum (Sam.) A. J. Li, F. urophyllum (Bur. & Franch.) H. Gross and F. gracilipes (Hemsl.) Damm. ex Diels, has the main vein extending from tepal base with some secondary veins. Evidence from tepal venation supports the previous classification in which Fagopyrum can be divided into a large-achene group and a small-achene group. Pollen morphology was investigated under a scanning electron microscope (SEM). The exine ornamentation of Pt. giraldii was finely reticulate with lumina diameter wider than muri width. The exine orna- mentation in all the examined Fagopyrum species is, however, prominently sunken punctuate. The phylogenetic analysis of nuclear ribosomal DNA (nrDNA) ITS sequences in Pteroxygonum and related genera indicated that all the species form a well-supported monophyletic group with two clades. One includes Polygonum sect. Avicularia Meisn., genus Fallopia and genus Reynoutria, and the other consists of other sections of Polygonum, genus Fagopyrum and Pteroxygonum. The latter clade can be divided into two subclades. Fagopyrum species compose the first one, while Pteroxygonum giraldii, species of Polygonum (except sect. Avicularia) and Antenoron form the second one. In consideration of the above evidence, we conclude that Pteroxygonum is an independent genus in tribe Persicarieae, and should not be merged into the genus Fagopyrum.

Xiang Dong

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