Flowers of annonaceae: Morphology, classification, and evolution

The present paper describes the diversity in floral characters of Annonaceae and their distribution over the family, and discusses their value for classification and generic delimitation. Flower morphology predominated historical classifications of this family since Hooker & Thomson (1855) introduced floral characters to divide the Asiatic genera into a number of tribes. Since then, several taxonomists presented a classification of the Annonaceae using floral characters, which classifications, however, are generally felt as unnatural. A survey of the flower morphology of all genera reveals a reticulate distribution of floral character states. Classification of the genera, as presented in this study, learns that floral characters different from those in previous classifications should be used if one aims at a better correlation with non-floral features. The chromosome number in this respect turned out to be an important character. Classification of the neotropical genera is relatively easy compared with classification of the African and Asiatic genera. Current genus delimitations in many cases are disputable. The functional aspects of the flower morphology are discussed in connection with a literature survey of the results from field studies on flower biology of Annonaceae. Some remarks on evolutionary aspects are added

Studies on the flora of the Guianas. 36. New taxa and combinations in Pourouma (Cecropiaceae)

The 23 species recognized in Pourouma are listed with their synonyms and distribution. Two new subspecies are described: P. melinonii Benoist subsp. glabrata C.C. Berg & van Heusden and P. tomentosa Miquel subsp. persecta Standley ex C.C. Berg & van Heusden. Ten new combinations are made: P. bicolor Martius subsp. chocoana (Standley) C.C. Berg & van Heusden, P. bicolor subsp. digitata (Trécul) C.C. Berg & van Heusden, P. bicolor subsp. scobina (Benoist) C.C. Berg & van Heusden, P. bicolor subsp. tessmannii (Mildbraed) C.C. Berg & van Heusden, P. guianensis Aublet subsp. venezuelensis (Cuatrecasas) C.C. Berg & van Heusden, P. hirsutipetiolata Mildbraed subsp. hispida (Standley & Cuatrecasas) C.C. Berg & van Heusden, P. mollis Trécul subsp. triloba (Trécul) C.C. Berg & van Heusden, P. tomentosa Miquel subsp. apiculata (Benoist) subsp. essequiboensis (Standley) C.C. Berg & van Heusden, and P. tomentosa subsp. maroniensis (Benoist) C.C. Berg & van Heusden. A key to the species and subspecies is presented. The present paper gives in a concise form the results of a revisional treatment of Pourouma and studies on behalf of treatments of the genus for the Flora of the Guianas and the Flora de Venezuela

Cecilanthus polymerus

A flower from the early Cenomanian of northeastern Maryland, Cecilanthus polymerus gen. et sp. nov., is described using SEM and synchrotron X-ray microtomography. The flower has >20 strap-shaped tepals, ca. 50 spathulate stamens with embedded adaxial pollen sacs and possibly H-valvate dehiscence, and ca. 100 more or less plicate carpels. Floral phyllotaxis is whorled, with >10 parts per whorl, but slightly irregular. Pollen and ovules are not preserved, but locule shape suggests the carpels are uniovulate. Similar characters occur in extant Magnoliales and the basal ANITA grade, but never in combination. In an attempt to resolve these ambiguities, we performed morphological phylogenetic analyses with the arrangement of extant taxa constrained to trees based primarily on molecular data. With anther dehiscence and ovule number treated as unknown, Cecilanthus has several most parsimonious positions: nested in Nymphaeales, nested in Magnoliales, sister to Laurales, and sister to Chloranthaceae. However, scoring anther dehiscence as H-valvate and ovule number as one increases support for a position in Magnoliales. Cecilanthus demonstrates that the early radiation of angiosperms produced floral morphotypes unlike those in any surviving taxa, and it illustrates the value of characters such as pollen morphology and seed anatomy for phylogenetic placement of floral mesofossils.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Panbiogeography of Nothofagus (Nothofagaceae): analysis of the main species massings

Aim  The aim of this paper is to analyse the biogeography of Nothofagus and its subgenera in the light of molecular phylogenies and revisions of fossil taxa. Location  Cooler parts of the South Pacific: Australia, Tasmania, New Zealand, montane New Guinea and New Caledonia, and southern South America. Methods  Panbiogeographical analysis is used. This involves comparative study of the geographic distributions of the Nothofagus taxa and other organisms in the region, and correlation of the main patterns with historical geology. Results  The four subgenera of Nothofagus have their main massings of extant species in the same localities as the main massings of all (fossil plus extant) species. These main massings are vicariant, with subgen. Lophozonia most diverse in southern South America (north of Chiloé I.), subgen. Fuscospora in New Zealand, subgen. Nothofagus in southern South America (south of Valdivia), and subgen. Brassospora in New Guinea and New Caledonia. The main massings of subgen. Brassospora and of the clade subgen. Brassospora/subgen. Nothofagus (New Guinea–New Caledonia–southern South America) conform to standard biogeographical patterns. Main conclusions  The vicariant main massings of the four subgenera are compatible with largely allopatric differentiation and no substantial dispersal since at least the Upper Cretaceous (Upper Campanian), by which time the fossil record shows that the four subgenera had evolved. The New Guinea–New Caledonia distribution of subgenus Brassospora is equivalent to its total main massing through geological time and is explained by different respective relationships of different component terranes of the two countries. Global vicariance at family level suggests that Nothofagaceae/Nothofagus evolved largely as the South Pacific/Antarctic vicariant in the breakup of a world-wide Fagales ancestor