Pollen morphology and systematics of palaeotropical Phyllanthus and related genera of subtribe Phyllanthinae (Euphorbiaceae)

The observations of pollen from 27 species of subtribe Phyllanthinae using scanning electron microscopy reveal considerable morphological diversity in palaeotropical Phyllanthus and the related palaeotropical genera Breynia, Glochidion, and Sauropus. The tribe appears to be monophyletic, but the pollen morphology does not support the monophyly of Phyllanthus or Sauropus. Within Phyllanthus, the pollen characters suggest a close relationship between the subgenera Emblica and Phyllanthodendron. They also reveal a surprising morphological congruence between the pollen grains of section Ceramanthus (subgenus Isocladus) and those of subgenus Eriococcus, although it is not clear whether this similarity is homoplastic. The presence of diploporate colpi is a synapomorphy uniting Breynia and Sauropus, but may be homoplastic in Phyllanthus. The affinities suggested by the morphological features of the pollen in the Phyllanthinae are concordant with recent molecular phylogenies. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 591–608.     

Pollen morphology of the Flueggeinae (Euphorbiaceae,Phyllanthoideae)

A total of 129 species from the subtribe Flueggeinae of the tribe Phyllantheae (Euphorbiaceae, Phyllanthoideae) were investigated using light and scanning electron microscopy, and 10 species using transmission electron microscopy, in order to evaluate the relationships between the eight constituent genera: Breynia, Flueggea, Glochidion, Margaritaria, Phyllanthus, Reverchonia, Richeriella, and Sauropus. Of these genera, Flueggea, Margaritaria and Richeriella share pollen with a prolate spheroidal meridional outline and a 3-colporate aperture system. Pollen of Reverchonia is also 3-colporate, but differs from that of the Flueggea alliance by its clearly prolate shape, tilioid ornamentation and absence of costae endopori. Breynia and Sauropus have 4–12 and 3–16-colporate pollen, respectively, with diploporate colpi. Two pollen types are recognised in Breynia, and four in Sauropus, one of which supports the recognition of Sect. Hemisauropus. Glochidion pollen is 3–6-colporate, and similar to that of Breynia in having reticulate sculpture with Y-shaped sexine structures, but it has monoporate colpi. Of the genus Phyllanthus, only species with pollen with diploporate colpi have been studied. Seven types are described. Diploporate Phyllanthus pollen can be distinguished from that of Breynia and Sauropus by its distinct colpus margins consisting of parallel muri. Colpal irregularities and endoaperture configurations in the subtribe are discussed, and pollen morphological trends are hypothesised. Placed in the successiform aperture series, the Flueggea alliance and Reverchonia form a basal group. Glochidion is considered intermediate, giving rise to the Breynia-Sauropus group. The relationship with Phyllanthus remains unclear.     

Wood anatomy of the subfamily Crotonoideae (Euphorbiaceae s.s.) from India: systematic implications with special reference to the taxonomic delimitation of Givotia and Vernicia

The wood anatomy of 15 representative species belonging to 12 genera of nine tribes of the subfamily Crotonoideae (Euphorbiaceae) are comprehensively described with focus on systematic implications. In addition, ecological and evolutionary aspects are evaluated. An identification key to the species based on wood anatomical features is presented. The wood microstructure of the tribes was found to be considerably heterogeneous reflecting an unnatural classification of the subfamily. However, the results confirm the generic relationship within subtribe Aleuritinae and tribe Ricinodendreae. Vernicia and Givotia may be recognized based on wood anatomical and morphological characters. The tribes Micrandreae and Adenoclineae have considerable similarity in wood anatomy. The wood structure of the monogeneric tribes Trigonostemoneae and Geloneae idicate a close relationship with the tribe Crotoneae.     

Multilayered structure of tension wood cell walls in Salicaceae sensu lato and its taxonomic significance

Salicaceae have been enlarged to include a majority of the species formerly placed in the polyphyletic tropical Flacourtiaceae. Several studies have reported a peculiar and infrequently formed multilayered structure of tension wood in four of the tropical genera. Tension wood is a tissue produced by trees to restore their vertical orientation and most studies have focused on trees developing tension wood by means of cellulose‐rich, gelatinous fibres, as in Populus and Salix (Salicaceae s.s.). This study aims to determine if the multilayered structure of tension wood is an anatomical characteristic common in other Salicaceae and, if so, how its distribution correlates to phylogenetic relationships. Therefore, we studied the tension wood of 14 genera of Salicaceae and two genera of Achariaceae, one genus of Goupiaceae and one genus of Lacistemataceae, families closely related to Salicaceae or formerly placed in Flacourtiaceae. Opposite wood and tension wood were compared with light microscopy and three‐dimensional laser scanning confocal microscopy. The results indicate that a multilayered structure of tension wood is common in the family except in Salix, Populus and one of their closest relatives, Idesia polycarpa. We suggest that tension wood may be a useful anatomical character in understanding phylogenetic relationships in Salicaceae. Further investigation is still needed on the tension wood of several other putatively close relatives of Salix and Populus, in particular Bennettiodendron, Macrohasseltia and Itoa.     

TheUlmaceae, one family or two? Evidence from chloroplast DNA restriction site mapping

The Ulmaceae is usually split into two subgroups, referred to as either tribes or more commonly subfamilies (Ulmoideae andCeltidoideae). The two groups are separated, with some exceptions, on the basis of leaf venation, fruit type, seed morphology, wood anatomy, palynology, chemistry, and chromosome number. Propositions to separate the two groups as distinct families have never gained general acceptance. Recent morphological and anatomical data have suggested, however, that not only is family status warranted but thatCeltidaceae are more closely related toMoraceae and otherUrticales than toUlmaceae. In order to test these alternative sets of relationships, restriction site mapping of the entire cpDNA was done with nine rare cutting enzymes using 11 genera ofUlmaceae s. l., three other families of theUrticales, and an outgroup family from theHamamelidae. Cladistic analysis of the data indicates thatUlmaceae s. l. is not monophyletic and that distinct families (Ulmaceae andCeltidaceae) are warranted; thatUlmaceae is the sister group toCeltidaceae plus all other families in the order; and thatCannabaceae might be nested withinCeltidaceae. Familial placements of various problematic genera (e.g.Ampelocera, Aphananthe) are resolved and character evolution of key morphological, anatomical, chemical, and chromosomal features are discussed.     

Chemical Composition of Cacti Wood and Comparison with the Wood of Other Taxonomic Groups

The aims of this study were to determine the wood chemical composition of 25 species of Cactaceae and to relate the composition to their anatomical diversity. The hypothesis was that wood chemical components differ in relationship to their wood features. The results showed significant differences in wood chemical compounds across species and genera (P < 0.05). Pereskia had the highest percentage of lignin, whereas species of Coryphantha had the lowest; extractive compounds in water were highest for Echinocereus, Mammillaria, and Opuntia. Principal component analysis showed that lignin proportion separated the fibrous, dimorphic, and non‐fibrous groups; additionally, the differences within each type of wood occurred because of the lignification of the vascular tissue and the type of wall thickening. Compared with other groups of species, the Cactaceae species with fibrous and dimorphic wood had a higher lignin percentage than did gymnosperms and Acer species. Lignin may confer special rigidity to tracheary elements to withstand desiccation without damage during adverse climatic conditions.     

中国算盘子属(叶下珠科)一些种的分类学处理

算盘子属(Glochidion J.R.G.Forst.)是叶下珠科(Phyllanthaceae)叶下珠族(Phyllantheae)中一个分类极为困难的类群。基于广泛野外考察与馆藏标本查阅,对中国该属部分物种进行分类学处理。其中,长柱算盘子[G.khasicum(Müll.Arg.)Hook.f.]与倒卵叶算盘子(G.obovatum SieboldZucc.)在中国的分布予以排除,菲岛算盘子[G.philippicum(Cav.)C.B.Rob.]在中国被发现仅分布于台湾地区;G.bodinieri H.Lév.,G.pseudo-obscurum var.glabrum Pamp.与G.pseudo-obscurum var.lanceolatum Pamp.这三个名称被处理为湖北算盘子(G.wilsonii Hutch.)的新异名;G.vaniotii H.Lév.被排除在算盘子属外,并接受为芸香科臭常春(Orixa japonica Thunb.)的异名。另外,对G.khasicum(Müll.Arg.)Hook.f.,G.obovatum SieboldZucc.,G.philippicum(Cav.)C.B.Rob.,G.pseudo-obscurum var.lanceolatum Pamp.及G.wilsonii Hutch.这五个名称进行了后选模式的指定。     

Comparative wood anatomy of the Cupressaceae and correspondence with phylogeny,with special reference to the monotypic taxa

Wood anatomy is one of the tools used for taxonomic classification of species. By combining this tool with molecular phylogeny, the current groupings made in morphological studies can be discussed. This study describes the wood anatomy of the monotypic genera of Cupressaceae and analyses the features that could represent synapomorphies of the principal clades recovered by molecular phylogeny. The wood anatomical study shows the high homogeneity of this family, revealing the presence of common ancestral features that support the union between Taxodiaceae and Cupressaceae s.s. and the separation of Sciadopitys. It also supports the group formed by Taxodiaceae in Cupressaceae s.l. No clear division was observed between the callitroid and cupressoid clades. Some wood anatomical differences were observed in the Fitzroya–Diselma–Pilgerodendron and Microbiota–Platycladus–Tetraclinis associations. The wood anatomical features common to the family, such as axial tracheids without helical thickenings, homogeneous rays, cupressoid cross-field pits and the presence of a warty layer, are put forward as possible synapomorphies for Cupressaceae s.l. The clade-specific synapomorphies are taxodioid cross-field pits for taxodioid and sequoioid clades, absence of a well-defined torus in Thuja–Thujopsis and torus extensions in Diselma–Fitzroya–Widdringtonia.     

The phylogenetic position of the endemic flat-needle pinePinus krempfii (Pinaceae) from Vietnam, based on PCR-RFLP analysis of chloroplast DNA

Pinus krempfii is morphologically very unique as compared to otherPinus species by having flat leaf-like needles. Its taxonomic position has been problematic ever since its discovery. In this study, an attempt was made to infer the taxonomic status ofP. krempfii through restriction fragment length polymorphism analysis of 12 PCR amplified chloroplast (cp) DNA regions. Phylogenetic analysis was conducted using 10 representatives of the twoPinus subgenera:Strobus andPinus. In addition, to infer the position ofP. krempfii in Pinaceae in relation with other genera, 14 representatives of eight additional genera were included in the analysis. Our cpDNA-based results indicate that: 1)P. krempfii clearly belongs to the genusPinus. This result does not favour the creation of a new genusDucampopinus in Pinaceae for this taxon. 2) Within the genusPinus, P. krempfii is more allied with species in subgenusStrobus and differs distinctly from species in subgenusPinus. 3) Despite the similarity in certain morphological and anatomical leaf and wood characters toKeteleeria andPseudolarix, the cpDNA data do not support the hypothesis for close relationship betweenP. krempfii and these two genera.     

DEVELOPMENTALLY VARIABLE,POLYMORPHIC WOODS IN CACTI

Sixteen genera of cacti were discovered to have polymorphic wood, that is, the plants produce one type of wood while young but a different type when older. The polymorphisms are: fibrous wood (with vessels and scanty paratracheal parenchyma) followed by parenchymatous wood (with vessels but few or no fibers) (Hylocereus venezuelensis, Dendrocereus nudiflorus, Borzicactus humboldtii, Haageocereus australis, Morawetzia sericata, Stephanocereus leucostele, Trichocereus schickendantzii); WBT wood (with wide-band tracheids, vessels, and apotracheal parenchyma but few or no fibers) followed by fibrous wood (Buiningia aurea, Oreocereus celsianus, Vatricania guentheri); WBT wood followed by parenchymatous wood (Echinopsis tubiflora, Gymnocalycium marsoneri, G. oenanthemum, Notocactus warasii, Parodia maassii); trimorphic wood in which WBT wood is followed by fibrous wood, which is followed by parenchymatous wood (Melocactus intortus, Arrojadoa braunii). The different phases within each plant may differ in vessel cluster size, percentage of the vessels that are solitary, diameter of vessels, and lignification of ray cells. Several of these genera are not closely related to the others, so wood polymorphism may have arisen several times.     

Pollen morphology of Chinese Glochidion (Phyllanthaceae) and its taxonomic implications

The pollen morphology of twenty‐five Chinese species belonging to two sections of Glochidion and one species from Phyllanthus subgen. Phyllanthodendron was examined using scanning electron microscopy (SEM). The results showed that pollen grains of Glochidion are isopolar, spheroidal to rarely subprolate in shape, (3)4–5(6)‐colporate in aperture pattern, and tectate‐reticulate to tectate‐rugulate in exine ornamentation. Fusion of colpus ends was observed in some pollen grains of G. pseudo‐obscurum and G. wrightii. The pollen grains of Phyllanthus dunnianus are similar to those of Glochidion species in their spheroidal shape and four‐colporate aperture pattern, but are slightly larger in size, and show tectate‐perforate exine ornamentation. In Glochidion, pollen morphology appears to be useful for distinguishing several macromorphologically similar. Additionally, palynological characters provide evidence for the taxonomy of the supergenus Phyllanthus s.l.     

Kritische Revision der „Thlaspi”︁-Arten Europas,Afrikas und Vorderasiens I. Geschichte,Morphologie und Chorologie

In the general introduction of a taxonomical revision of the genus Thlaspi L. from Europa, the Near East and Africa — a conspectus of the species till now comprised within this genus has already been published — a historical survey of the genus Thlaspi is given. Morphological resp. anatomical characters have been judged. The structure of the seedtesta inter alia exhibited a different pattern which proved to be valuable for differentiation. In Thlaspi s. str. this pattern revealed to be well distinguishable from all the other Thlaspi-species hitherto put in this genus; thus showing Thlaspi s. str. a species-complex of its own. The characteristical differences of the numerous species out of the Thlaspi s. str.-complex allow further separation of different genera, so that the hitherto existing genus Thlaspi has been found to be a mosaic of different genera. The degree of their closer or wider relationship, however, could be investigated after extensive studies in different genera of the Brassicaceae (Cruciferae). A subordination of these complexes of closer relationship as subgenera of the genus Thlaspi is impossible, because the morphological and anatomical differences are too great. A persistency in the hitherto scope of a heterogenous genus Thlaspi is considered unreasonable and would encourage a greater humping of many genera within the family Brassicaceae which are well separated till now. This would not reflect the natural conditions. Additional figures of fruits and seedtestas of different species support this view. Finally the geographical distribution of the several genera has been described which in Noccaea Moench shows shortly the wide extension of this genus throughout northern Asia and the extratropical America.     

Comparative wood anatomy of Andromedeae s.s., Gaultherieae, Lyonieae and Oxydendreae (Vaccinioideae, Ericaceae s.l.)

The wood anatomical structure of 11 out of 13 genera from four tribes of the Vaccinioideae, namely Andromedeae s.s. , Gaultherieae, Lyonieae and Oxydendreae (Ericaceae s.l. ), is described using light and scanning electron microscopy. Several features of the secondary xylem support the tribal classification based on molecular data: arrangement of vessel-ray pitting, height of multiseriate rays and the shape of the body ray cells. Oxydendreae are clearly defined from the other representatives by various wood anatomical features. Gaultherieae can be distinguished from Lyonieae by differences in vessel perforation plates, vessel-ray pitting, height and structure of multiseriate rays, and occurrence of prismatic crystals, but the wood of Andromedeae s.s. is similar to Gaultherieae. Moreover, Andromedeae s.s. , Oxydendreae and Vaccinieae are characterized by their pith structure, whereas considerable variation in the pith cells is found in Lyonieae and Gaultherieae.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 161–179.     

Evolution of obligate pollination mutualism in the tribe Phyllantheae (Phyllanthaceae)

The landmark discovery of obligate pollination mutualism between Glochidion plants and Epicephala moths has sparked increased interest in the pollination systems of Phyllantheae plants. In this paper I review current information on the natural history and evolutionary history of obligate pollination mutualism in Phyllantheae. Currently, an estimated >500 species are mutualistic with Epicephala moths that actively pollinate flowers and whose progeny feed on the resulting seeds. The Phyllantheae also includes species that are not mutualistic with Epicephala moths and are instead pollinated by bees and/or flies or ants. Phylogenetic analyses indicate that the mutualism evolved independently five times within Phyllantheae, whereas active pollination behavior, a key innovation in this mutualism, evolved once in Epicephala . Reversal of mutualism has occurred at least once in both partner lineages, involving a Breynia species that evolved an alternative pollination system and a derived clade of Epicephala that colonized ant-pollinated Phyllantheae hosts and thereby lost the pollinating habit. The plant–moth association is highly species specific, although a strict one-to-one assumption is not perfectly met. A comparison of plant and moth phylogenies suggests signs of parallel speciation, but partner switches have occurred repeatedly at a range of taxonomic levels. Overall, the remarkable species diversity and multiple originations of the mutualism provide excellent opportunities to address many important questions on mutualism and the coevolutionary process. Although research on the biology of the mutualism is still in its infancy, the Phyllantheae– Epicephala association holds promise as a new model system in ecology and evolutionary biology.