Leaf Architectural Characters Research Articles

Phylogenetic analysis of Cabombaceae and Nymphaeaceae based on vegetative and leaf architectural characters

AbstractVegetative and leaf architectural characters are used to assess the phylogenetic relationships of species of Cabombaceae and Nymphaeaceae. Twenty‐eight species representing all eight genera and the five subgenera of Nymphaea are analyzed. These morphological analyses give robust support to other molecular and morphological analyses of the relationships of the two families. There is strong support for the two families to be monophyletic, and that Euryale and Victoria are closely related. Strict consensus analyses show that within the Nymphaeaceae, Nuphar is the first sister clade, followed by Barclaya and finally by a polytomy of Ondinea, Euryale‐Victoria and Nymphaea. The relationships of Ondinea are uncertain, in part due to missing characters. Finally, the genera of each family are monophyletic. Each genus has a suite of distinctive vegetative characteristics that are used to make an identification key of the genera. Although the value of vegetative and leaf architectural characters is shown, inclusion of atypical leaves, for example some types of submerged leaves, results in less resolved or robust trees.

Leaf architecture of Hamelieae (Rubiaceae)

AbstractThe tribe Hamelieae sensu Robbrecht comprises seven genera, and is traditionally placed in subfamily Rubioideae. Molecular data, however, places Hamelieae within Cinchonoideae. In this study, leaf architecture characters were examined in order to provide further evidence for the circumscription of Hamelieae and discuss its placement in the proposed subfamilies. Leaves from 34 species belonging to six genera of the Hamelieae, plus Syringantha and representative species of Psychotrieae (Rubioideae), Cinchoneae (Cinchonoideeae) and Gardenieae (Ixoroideae) were studied in order to describe and compare their leaf architecture. The results showed that there are macromorphological characters shared by members of Hamelieae. The venation of Hamelieae is brochidodromous, as in the other sampled taxa, except Bouvardia, which has actinodromous venation and Randia with eucamptodromous‐brochidodromous venation. In Hamelieae and Psycho‐ trieae, marginal ultimate venation forms a fimbrial vein and raphides are present in the mesophyll, while in representatives of Cinchoneae and Gardenieae, marginal ultimate venation is incomplete and raphides are absent. Syringantha is distinguished by its narrow elliptical to lanceolate lamina, but shares several attributes with Hamelia and Hoffmannia. These attributes support the proposal to include Syringantha in Hamelieae. The results neither resolve the placement of Hamelieae in Rubioideae or Cinchonoideae. However, our current phylogenetic understanding of the family, placing this tribe in a clade within Cinchonoideae, suggests that raphides arised more than once independently, thus raphides should not be a taxonomic marker to define the Rubioideae. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Leaf Architecture of Subtribe Micheliinae (Magnoliaceae) from China and Its Taxonomic Significance

Leaf architectural and morphological characters of 28 taxa from Michelia, Paramichelia and Tsoongiodendron (Magnoliaceae sensu stricto, subtribe Micheliinae) were examined to gain a better understanding of the intergeneric relationships and the systematic positions of some species within Michelia. The taxa examined, all of which have simple leaves with entire margins and camptodromous pinnate venation, varied in their secondary venation, which was brochidodromous or brochidodromous to eucamptodromous, the mixture of simple and composite intersecondary veins, percurrent to reticulate tertiary veins. Dendroid veinlets were recorded for the first time in Michelia species. Phenetic analyses of leaf architectural characters and morphological characters suggested that Paramichelia and Tsoongiodendron are grouped together and merged in the Michelia, and these characters provide useful taxonomic information for division of sections in Michelia. In addition, systematic positions of some species in Michelia are discussed.

Character evolution in Anaxagorea (Annonaceae)

Anaxagorea is a critical genus for understanding morphological evolution in Annonaceae because it shares a variety of features with other Magnoliales that have been interpreted as primitive relative to other Annonaceae. We present a detailed discussion of morphological characters used in a combined morphological and molecular phylogenetic analysis of Anaxagorea, along with implications of the analysis for character evolution in the genus. In spite of a high level of homoplasy in stamen and leaf venation characters, their removal results in loss of resolution in the trees obtained. The distributions of characters on trees confirm assumptions that several distinctive similarities between Anaxagorea and other Magnoliales are primitive retentions (e.g., the presence of an adaxial plate of xylem in the midrib, nonpeltate stamen connectives, inner staminodes, and several leaf architectural characters). However, lateral extensions of the “laminar” stamens, though possibly ancestral in Anaxagorea, are convergent with those in other Magnoliales. A number of morphological synapomorphies have been identified for a clade containing most Central American species and another comprising all Asian species (e.g., conical bud shape and reduced inner petals for the Central American clade, and adaxial cuticular striations and capitate stigma shape for the Asian clade).

Leaf Architecture and Epidermal Characters of the Argentinean Species of Proteaceae

We describe the leaf architecture (venation and cuticle) of the eight extant species of Argentinean Proteaceae and discuss the diagnostic value of the characters. Proteaceae leaves are characterized by several architectural features. The leaves are ovate to oblong‐lanceolate or elliptic, with coriaceous texture, and have normal‐marginal petiole; the apexes vary between acute and obtuse, while the bases are acute to decurrent. They have pinnate simple first‐category venation, lack agrophic veins, have well‐developed areoles, and have two‐or‐more‐branched freely ending ultimate veins. Furthermore, all species have brachyparacytic stomata restricted to the abaxial surface of the leaves and multicellular trichomes. Cuticle features that differ among the species are the presence or absence of glands and papillae, and stomata size in relation to epidermal cell size. Architectural and cuticular features are also useful for differentiating tribes, subtribes, genera, and species within the subfamily Grevilleoideae. A key for the identification of Argentinean Proteaceae based only on leaf and cuticle characters is presented.

Leaf architecture in Quercus subgenus Cyclobalanopsis (Fagaceae) from China

Leaves of 46 species of Quercus subgenus Cyclobalanopsis were studied. A comprehensive description of leaf architecture for subgenus Cyclobalanopsis is provided. Ten leaf architectural characters were examined, including leaf venation type, tooth type, areoles, veinlets and marginal ultimate venation. Four types of venation pattern and three types of teeth are recognized. Evolutionary trends of some leaf architectural features, e.g. venation pattern, tooth type, tertiary veins, areoles and veinlets, are suggested. Based on the comparison of leaf architecture of subgenus Cyclobalanopsis, subgenus Quercus and Trigonobalanus doichangensis, we support the taxonomic treatment of Cyclobalanopsis as a subgenus of Quercus and speculate that subgenus Cyclobalanopsis is relatively primitive within the genus Quercus. (C) The Linnean Society of London

A diverse assemblage of Anacardiaceae from Oligocene sediments, Tepexi de Rodriguez, Puebla, Mexico

Among the plants collected from the Pie de Vaca Formation of the Oligocene, of Tepexi de Rodríguez, Puebla, México are five plants of Anacardiaceae, Haplorhus medranoensis, Rhus toxicodendron, Rhus sp., Comocladia intermedia, and Pistacia marquezii represented by their leaves and/or leaflets. The past and present diversity and geographic distribution of one of these genera, Rhus, demonstrate its capability to adapt and diversify in a wide variety of environments. Leaf architecture characters of this taxon overlap with those of other genera in the family, suggesting a high degree of phenotypic plasticity. The presence in the Pie de Vaca Formation of a type of Pistacia with leaf architecture characters similar to those of Asian plants further supports a long history of exchange between low-latitude North America and Asia. Links between low-latitude North and South America and the Caribbean are suggested by the presence of Comocladia and Haplorhus. Whereas Comocladia highlights the long history of regional endemics in the area, Haplorhus, today an endemic monotypic genus of Peru, suggests exchange mechanisms between North and South America. The morphologic characters of these taxa, and those of Pseudosmodingium (Anacardiaceae), some Rosaceae, Leguminosae, and Berberidaceae, suggest that the Pie de Vaca community was established and evolved in harsh environmental conditions. The Pie de Vaca flora thus provides significant new insights into the biogeographic relationships of the low latitude vegetation of North America.

Leaf architecture and epidermal characters in Zelkova, Ulmaceae

Abstract Zelkova , with six extant species in Eurasia – three in East Asia ( Z. schneideriana , Z. serrata , Z. sinica ), one in south-western Asia ( Z. carpinifolia ) and two in southern Europe ( Z. abelicea , Z. sicula ) – was investigated with respect to leaf architecture and epidermal characters by LM and SEM. The leaf venation of Zelkova is relatively uniform, while leaf size and shape are highly variable. Characters such as teeth and epidermal cells, trichomes and stomata provide useful specific distinctions. Beginning in the Miocene, increasing aridity in Central Asia would appear to have been responsible for isolating the eastern Asiatic species from their European/western Asiatic counterparts. The European range underwent further changes in response to Quaternary climatic oscillations.

Leaf architecture and epidermal characters in Zelkova, Ulmaceae

Zelkova, with six extant species in Eurasia – three in East Asia (Z. schneideriana, Z. serrata, Z. sinica), one in south-western Asia (Z. carpinifolia) and two in southern Europe (Z. abelicea, Z. sicula) – was investigated with respect to leaf architecture and epidermal characters by LM and SEM. The leaf venation of Zelkova is relatively uniform, while leaf size and shape are highly variable. Characters such as teeth and epidermal cells, trichomes and stomata provide useful specific distinctions. Beginning in the Miocene, increasing aridity in Central Asia would appear to have been responsible for isolating the eastern Asiatic species from their European/western Asiatic counterparts. The European range underwent further changes in response to Quaternary climatic oscillations.

The Phylogenetic Affinities of Nothofagus (Nothofagaceae) Leaf Fossils based on Combined Molecular and Morphological Data.

The phylogenetic placements of leaf fossils of Nothofagus (Nothofagaceae) were determined using parsimony analyses of molecular and morphological data for extant species combined with morphological data for fossils. Placement was possible for only seven of the 30 or so described fossil species of Nothofagus because only these had sufficiently good preservation of both cuticular and leaf architectural characters. In combined analyses of morphology and molecular data, leaf cuticular characters showed little homoplasy. In contrast, many architectural characters, including some leaf margin and venation characters, showed high homoplasy, making it difficult or impossible to accurately determine the phylogenetic affinities of impression fossils of this genus.

Petermanniopsis angleseaënsis Gen. & Sp. Nov.: An Australian Fossil Net- Veined Monocotyledon from Eocene Victoria

A new species of fossil reticulate-veined monocot, Petermanniopsis angleseaënsis gen. & sp. nov., is described from a mummified leaf base from the Anglesea Coal Deposit in Victoria, Australia. Cluster analysis and multidimensional scaling ordination of a range of leaf architectural and cuticular characters place it closest to the extant Australian monotypic and endemic Liliiflorae family Petermanniaceae from the temperate rain forests of southeastern Queensland and northeastern New South Wales. In contrast, a parsimony analysis of this same data set failed to resolve its position clearly within a clade representing the strongly net-veined Dioscorealean taxa. Although the presence of a fossil with affinities to the Petermanniaceae from Eocene Victoria supports the idea that the group represents an isolated member of the net-veined Liliiflorae autochthonous to Australia, this study also highlights the difficulty involved in assigning such fossils to modern monocot groups, or even distinguishing between these groups themselves, particularly in cladistic studies using leaf architecture. Therefore, although most similar phenetically to the Petermanniaceae, the fossil is maintained as incertae cedis affinis Petermanniaceae. Nevertheless, the presence of an Eocene Gondwanan net-veined monocot supports the thesis that the group is an early evolutionary development in the evolution of the Liliiflorae.

Systematic Foliar Morphology of Phyllanthoideae (Euphorbiaceae). II. Phenetic Analysis

Cladistic analysis of 43 foliar characters was used to explore the phylogeny of genera in Phyllanthoideae and to test the systematic value of foliar morphology. Character polarities were assessed by outgroup analysis treating other subfamilies of Euphorbiaceae and primitive genera in Flacourtiaceae as outgroups. Results indicated that several major tribes recognized in the most recent classification of the subfamily are essentially monophyletic, including Aporuseae, Bridelieae, Drypeteae, and most of Wielandieae, whereas others, notably Antidesmeae, are probably paraphyletic. Conflicts between leaf-based cladograms and the previous classification appeared in the relationships of Astrocasia, Didymocistus, Neowawraea, and genera in Amanoeae, but relationships were clarified for genera like Bischofia, Uapaca, and Hymenocardia, whose positions have previously been obscure. These results verify the systematic value of foliar characters. However, the rates of homoplasy found in this study are higher than found in most cladistic analyses, possibly indicating that many foliar characters are of most value at lower taxonomic levels. Relatively conservative characters include outer vein loop size, tertiary vein pattern, areolation development, unicellular trichome type, and tanniniferous epidermal cells. In the last fifteen years, the success paleobotanists have had using leaf architectural and epidermal characters to classify fossil leaves (Hickey 1971, 1977; Wolfe 1972, 1973; Dilcher 1974; Doyle and Hickey 1976) has led some systematists to explore the usefulness of these characters with extant plants (e.g., see Baranova 1972; Hickey and Wolfe 1975; Raju and Rao 1977; Rury and Dickison 1977; Den Hartog and Baas 1978; Hickey 1980; Bedel 1981). In general, these workers found close concordance between relationships suggested by foliar characters and traditional classifications, a result that seriously challenges the widely held belief that leaves are of little systematic value, especially at higher taxonomic levels (for the traditional view, see Stebbins 1950:515-516; Good 1964:312; Cronquist 1968:39). Before foliar characters could be used successfully, character sets that both adequately describe the range of leaf morphology and can be used with modern analytic techniques had to be developed. Particularly important contributions were made by Stace (1965), who catalogued epidermal characters (see also Dilcher 1974), and Hickey (1973), who developed a system of terminology for describing leaf architecture. Later, Dolph (1976) and Hill (1980) attempted to apply numerical phenetic techniques with these and other leaf character sets. Using collections of leaves randomly drawn from trees of various families, they found that within species leaves varied little enough that they clustered separately from those of other species, but that the patterns of similarity represented by the leaf-based phenograms did not correspond to generic or familial relationships among the plants. As part of an ongoing study of the foliar morphology of Euphorbiaceae, I analyzed leaf architectural and epidermal characters of Phyllanthoideae, putatively the most primitive subfamily, using a numerical phenetic method called Similarity Graph Clustering (Wirth et al. 1966; Legendre and Rogers 1972). My results (Levin 1986b) contrasted markedly with those of Dolph (1976) and Hill (1980). Using sections or undivided genera as my taxonomic units, I found that the major groups suggested by similarity of leaf characters corresponded remarkably well with higher taxa in the most recent classification of the subfamily (Webster 1975), which was based on characters more widely recognized as being of systematic value, particularly floral morphology, pollen morphology, and wood anatomy. There were, however, specific genera that did not cluster with other members of the tribes to which Webster assigned them. In many such cases, other data suggested that the classification was questionable and instead corroborated the leaf evidence. In the remaining cases, the source of the