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Full-Text Articles in Life Sciences

Comparative Vegetative Anatomy And Systematics Of Oncidiinae (Maxillarieae, Orchidaceae), William Louis Stern, Barbara S. Carlsward Jan 2006

Comparative Vegetative Anatomy And Systematics Of Oncidiinae (Maxillarieae, Orchidaceae), William Louis Stern, Barbara S. Carlsward

Barbara S. Carlsward

Subtribe Oncidiinae comprises a vegetatively heterogeneous assemblage of species that has persistently been incapable of organization. Anatomy was considered to be a possible means to resolve the perplexity of relationships amongst the constituent taxa. The consistent occurrence of a foliar hypodermis, homogeneous mesophyll, conical silica bodies in stegmata, and ubiquitous fibre bundles in leaves provides a matrix for linking the taxa, as do the parenchymatous pith and O-thickened endodermal cell walls in roots. However, the strict consensus of the 40 genera studied was completely unresolved, suggesting that vegetative characters alone are insufficient to assess the relationships amongst these taxa, a ...


Molecular Phylogenetics Of Vandeae (Orchidaceae) And The Evolution Of Leaflessness, Barbara S. Carlsward, W. Mark Whitten, Norris H. Williams, Benny Bytebier Jan 2006

Molecular Phylogenetics Of Vandeae (Orchidaceae) And The Evolution Of Leaflessness, Barbara S. Carlsward, W. Mark Whitten, Norris H. Williams, Benny Bytebier

Barbara S. Carlsward

Members of tribe Vandeae (Orchidaceae) form a large, antropical clade of horticulturally important epiphytes. Monopodial leafless members of Vandeae have undergone extreme eduction in habit and represent a novel adaptation to the canopy environment in tropical Africa, Asia, and America. To study the evolution of monopodial leaflessness, molecular and structural evidence was used to generate phylogenetic hypotheses for Vandeae. Molecular analyses used sequence data from ITS nrDNA, trnL-F plastid DNA, and matK plastid DNA. Maximum parsimony analyses of these three DNA regions each supported two subtribes within monopodial Vandeae: Aeridinae and a combined Angraecinae รพ Aerangidinae. Adding structural characters to ...


Comparative Vegetative Anatomy And Systematics Of The Angraecoids (Vandeae, Orchidaceae) With An Emphasis On The Leafless Habit, Barbara S. Carlsward, William Louis Stern, Benny Bytebier Dec 2005

Comparative Vegetative Anatomy And Systematics Of The Angraecoids (Vandeae, Orchidaceae) With An Emphasis On The Leafless Habit, Barbara S. Carlsward, William Louis Stern, Benny Bytebier

Barbara S. Carlsward

The vegetative anatomy and morphology of 142 species of the angraecoid orchids (Angraecinae + Aerangidinae) and 18 species of Aeridinae were examined using light and scanning electron microscopy. Leafless members of Vandeae were of particular interest because of their unique growth habit. Leafy and leafless members of Angraecinae and Aerangidinae were examined and compared with specimens of Aeridinae. Vandeae were homogeneous in both leaf and root anatomy. A foliar hypodermis and fibre bundles were generally absent. Stegmata with spherical silica bodies were found associated with sclerenchyma and restricted to leaves in almost all specimens examined. Distinct inner tangential wall thickenings of ...