Alexei A. Oskolski

Flower structure and development in Tupidanthus calyptratus (Araliaceae): an extreme case of polymery among asterids

Flowers of Tupidanthus show an extreme case of floral polymery among asterids. Floral development and gynoecium structure have been examined. The floral meristem has a complex folded shape. The tiny calyx is initiated as a continuous ring primordium. The corolla is initiated as a lobed ring and develops into a calyptra. All stamen primordia appear simultaneously as a single whorl. The carpels, also in a single whorl, tend to alternate with the stamens. Some Schefflera species related to Tupidanthus are also studied. The flower of Tupidanthus is interpreted as a result of fasciation. Further investigation should determine whether mutation(s) in gene(s) of the CLAVATA family are responsible for the fasciation here. The significance of Tupidanthus for understanding spatial pattern formation in flowers of Araliaceae, and both functional and developmental constraints in angiosperm flowers with a single polymerous carpel whorl are discussed.

Phylogenetic position of the genus Ferula (Apiaceae) and its placement in tribe Scandiceae as inferred from nrDNA ITS sequence variation

Recent molecular systematic investigations suggested that Ferula, an umbellifer genus of about 170 species, is polyphyletic, with its members placed in the apioid superclade and within tribe Scandiceae. We analyzed ITS sequence variation from 134 accessions of Apiaceae, including 83 accessions (74 species) of Ferula to ascertain the phylogenetic position of the genus within the family. Phylogenetic analyses of these data using maximum parsimony, Bayesian, and neighbor-joining methods support the monophyly of Ferula upon the addition of Dorema and Leutea (as Ferula sensu lato) and its placement in tribe Scandiceae. Ferula sensu is closely allied with other major lineages of Scandiceae, corresponding to subtribes Scandicinae, Daucinae, and Torilidinae. Therefore, we recognize the Ferula clade as subtribe Ferulinae. Another addition to tribe Scandiceae is a clade composed of genera Glaucosciadium and Mozaffariania. The three accessions of Ferula misplaced in the apioid superclade represent a species of Silaum.

EARLY LINEAGES IN APIALES: INSIGHTS FROM MORPHOLOGY, WOOD ANATOMY AND MOLECULAR DATA

Recent molecular studies indicate that the araliaceous tribes Myodocarpeae R. Vig. ( Delarbrea Vieill., Pseudosciadium Baill. and Myodocarpus Brongn. & Gris.) and Mackinlayeae R. Vig. ( Apiopetalum Baill., Mackinlaya F. Muell. and several genera of Hydrocotyloideae Link ( Apiaceae )) comprise basally branching lineages within Apiales , an interpretation consistent with data from morphology and wood anatomy. Comparison of selected features in these genera, and in close relatives of Apiales , suggests that ancestral character states for the order may include: simple leaves, inflorescences in panicles of umbellules, flowers with articulated pedicels and a bicarpellate gynoecium, an andromonoecious, duodichogamous sexual system, septate fibres, the absence of radial canals, and the presence of paratracheal axial parenchyma in the wood.

PHYLOGENETIC RELATIONSHIPS WITHIN APIALES: EVIDENCE FROM WOOD ANATOMY

Wood anatomical data confirm the close relationships of most Araliaceae to Apiaceae , but do not indicate any intermediate groups between the two families. Heteromorpha Cham. & Schltdl., Bupleurum L. and Melanoselinum Hoffm. form a well-delimited group distinguished from other woody Apiaceae by helical thickenings on their vessel walls, septate fibres, and mostly homogeneous rays. The woodiness in Nirarathamnos Balf.f. and Myrrhidendron J. M. Coult. & Rose is likely to be of secondary origin.

Wood Anatomy of Schefflera and Related Taxa (Araliaceae)

The wood anatomy of 31 Schefflera species from Indochina, Australia, Oceania, Africa, and South America, 3 species of Didymopanax from South America, and Tupidanthus calyptratus and Scheffleropsis hemiepiphytica from Indochina (Araliaceae) are described. Seven groups of species can be recognised.

WOOD ANATOMY OF SCHEFFLERA AND RELATED TAXA (ARALIACEAE). II. SYSTEMATIC WOOD ANATOMY OF NEW CALEDONIAN SCHEFFLERA

The wood anatomy of 22 of the 26 species of Schefflera occurring in New Caledonia was studied. Only two features (the presence of scalariform perforation plates and scanty paratracheal axial parenchyma) appear to be constant throughout the species examined. The pattern of wood structure diversity was analyzed using PCA; the results generally agree with the current recognition of four groups of species among New Caledonian Schefflera based on macromorphology. Three of these groups (Dizygotheca, “Canacoschefflera” and “Gabriellae”) represent natural assemblages closely related to one another. The fourth group (Schefflera sect. Schefflera) is isolated from the others, as indicated by its very large rays and abundant septate fibres. The occurrence of crystals in chambered cells of axial parenchyma was observed for the first time in Araliaceae. The wood structure of Schefflera plerandroides, previously placed in the segregate genus Octotheca, shows no essential differences from that of the other members of the Dizygotheca group, supporting the hypothesis that polymerous flowers have evolved independently at least twice within the Schefflera alliance.

Altingioxylon hainanensis sp. nov.: earliest fossil wood record of the family Altingiaceae in Eastern Asia and its implications for historical biogeography

A new species, Altingioxylon hainanensis, is described from the Eocene Changchang Formation of the Changchang Basin on Hainan Island, South China. It is the first record of a fossil wood assigned to Altingiaceae found in China, and the most ancient evidence of wood for this family in eastern Asia. The new species is similar to A. rhodoleioides, known since the Miocene in India and Java Island, and to Altingiahisauchii from the Miocene to Pliocene of Japan. The close resemblance between these species and Liquidambar sp., known from the Middle Miocene of western North America, provides additional evidence for the migration of their ancestors from Asia to North America across the Bering land bridge during the Miocene. Distinctions in ray sizes between the eastern Asian specimens and their contemporaries from Europe to Kazakhstan is suggested as a result of the divergence between the large eastern Asian clade and the North American–west Asian clade within Altingiaceae during the Eocene–Oligocene. The presence of crystals in ray cells may be considered an ancestral condition that persists in the eastern Asian lineages up to the extant Altingia and Semiliquidambar, but which was lost in other Altingiaceae in the course of evolution.

Floral Anatomy of Asian Schefflera (Araliaceae, Apiales): Comparing Variation of Flower Groundplan and Vascular Patterns

Floral morphology and vascular anatomy in members of the Asian Schefflera clade (Araliaceae) are studied. This clade is of special interest because of secondary loss of flower groundplan stability and increase of merism. Among five species studied, three have isomerous pentamerous flowers, one has (almost) isomerous polymerous flowers, and one has nonisomerous flowers as a result of increased carpel number. Loss of calyx innervation and reduction of sepals are suggested as apomorphic for the subclade Heptapleurum s.l. Tupidanthus calyptratus, a member of this subclade with the most polymerous gynoecium among asterids, shares those features, too. Range of petal venation diversity within the species examined exceeds what was previously estimated for the family Araliaceae and the order Apiales. Formation of anastomoses between the bundles of petals and stamens in bisexual flowers of Schefflera venulosa is suggested as an effect of high auxin production in developing anthers. A shift of the ovule supply from ventral bundles to lateral ones occurs in different lineages of Apiales. Fusion between peripheral and dorsal bundles is an effect of flower topography that may not be considered an advanced character state. Strong differences in floral vasculature between closely related species with the same flower groundplan are highlighted.

Distribution of scalariform and simple perforation plates within the vessel network in secondary xylem of Araliaceae and its implications for wood evolution

The distribution of scalariform and simple perforation plates along vessels in Arthrophyllum otopyrenum, Meryta tenuifolia, and Polyscias multijuga (Araliaceae) is examined. In all three species, most vessels bear simple perforation plates only, but the combination of simple and scalariform perforation plates in variable ratios also occurs. Aggregated arrangement of scalariform perforation plates along the vessels was statistically confirmed in some vessel portions. The scalariform perforation plates occur mostly in narrow vessels that are grouped in multiples. Within the clade represented by Polyscias and Arthrophyllum, the evolutionary transition from scalariform to simple perforation plates is realized as the gradual elimination of vessels or vessel portions with scalariform perforation plates, but is not accompanied by a gradual decrease of the number of bars per perforation plate. The narrow vessels that are grouped in vessel multiples are likely to retain the ability to develop scalariform plates, which could promote the evolution from simple to scalariform perforation plates as is the case within Meryta.

Camellia nanningensis sp. nov.: the earliest fossil wood record of the genus Camellia (Theaceae) from East Asia

A new species Camellia nanningensis was described on the basis of well-preserved mummified wood from the upper Oligocene Yongning Formation of Nanning Basin in Guangxi Province, South China. This represents the most ancient fossil wood assigned to Camellia, and the earliest fossil record of the family Theaceae in China. This fossil material shows that Camellia occurred in China as early as the late Oligocene, suggesting more ancient radiation of this genus than estimated by molecular dating.