Although the matK gene has been used in addressing systematic questions in four families, its potential application to plant systematics above the family level has not been investigated. This paper examines the rates, patterns, and types of nucleotide substitutions in the gene and addresses its utility in constructing phylogenies above the family level. Eleven complete sequences from the GenBan...

Casuarinaceae are a Gondwanic family with a unique combination of morphological characters not comparable to any other family. Until recently, the 96 species in the family were classified in a single genus, Casuarina s.l. A recent morphological revision of the family resulted in the splitting of Casuarina s.l. into four genera-Allocasuarina, Casuarina s.s., Ceuthostoma, and Gymnostoma. This stu...

Aceraceae is a large forest tree family that comprises many economically and ecologically important species. However, because interspecific and/or intraspecific morphological variations result from frequent interspecific hybridization and introgression, it is challenging for non-taxonomists to accurately recognize and identify the tree species in Aceraceae based on a traditional approach. DNA b...

PREMISE OF STUDY Many angiosperms have fruit morphologies that result in seeds from the same plant having different dispersal capabilities. A prime example is found in the Brassiceae (Brassicaceae), which has many members with segmented or heteroarthrocarpic fruits. Since only 40% of the genera are heteroarthrocarpic, this tribe provides an opportunity to study the evolution of an ecologically ...

DNA barcodes have been increasingly used in authentication of medicinal plants, while their wide application in materia medica is limited in their accuracy due to incomplete sampling of species and absence of identification for materia medica. In this study, 95 leaf accessions of 23 species (including one variety) and materia medica of three Pharmacopoeia-recorded species of Angelica in China w...

The recently described polyploid Saxifraga svalbardensis is endemic to the arctic archipelago of Svalbard. We investigated relationships among four closely related species of Saxifraga in Svalbard and tested three previously proposed hypotheses for the origin of S. svalbardensis: (1) differentiation from the morphologically and chromosomally variable polyploid S. cernua; (2) hybridization betwe...

Biological invasions are regarded as threats to global biodiversity. Among invasive aliens, a number of plant species belonging to the genera Myriophyllum, Ludwigia and Cabomba, and to the Hydrocharitaceae family pose a particular ecological threat to water bodies. Therefore, one would try to prevent them from entering a country. However, many related species are commercially traded, and distin...

The genus Primula is extremely diverse in the east Himalaya-Hengduan Mountains (HHM) in China as a result of rapid radiation. In order to overcome the difficulty of morphological classification of this genus, we surveyed three plastid regions (rbcL, matK, and trnH-psbA) and two nuclear markers (ITS and ITS2) from 227 accessions representing 66 Primula species across 18 sections, to assess their...

We have generated matK, rbcL, and nrITS2 DNA barcodes for 320 specimens representing all 18 extant genera of the conifer family Podocarpaceae. The sample includes 145 of the 198 recognized species. Comparative analyses of sequence quality and species discrimination were conducted on the 159 individuals from which all three markers were recovered (representing 15 genera and 97 species). The vast...

We answer three problems by J. D. Monk on cardinal invariants of Boolean algebras. Two of these are whether taking the algebraic density πA resp. the topological density dA of a Boolean algebra A commutes with formation of ultraproducts; the third one compares the number of endomorphisms and of ideals of a Boolean algebra. In set theoretic topology, considerable effort has been put into the stu...