Platanus Species Research Articles

Aerobiological behaviour of Platanus L. pollen in Catalonia (North-East Spain)

The aim of this paper is to characterise theairborne behaviour of an allergenic andabundant pollen type, Platanus, in sevensites of the Aerobiological Network ofCatalonia (Xarxa Aerobiologica deCatalunya, XAC). In Catalonia, the mostextended Platanus species is Platanus × hybrida Brot., widely planted inforestry and as ornamental tree in streets andgardens. Naturalised specimens can also befound along river banks.The pollen records analysed are from differentperiods comprised between 1994 and 2000 inBarcelona, Bellaterra, Cambrils, Girona,Lleida, Manresa and Tarragona. All data wereobtained using seven-day volumetric spore Hirsttraps.Platanus pollination is concentrated in afew weeks, between March and April. Platanus pollen is present in all theatmospheric pollen spectra for the sitesmentioned above. In Barcelona, Platanuspollen attained the highest concentrations,with an extreme annual index (sum of the meandaily concentrations) of 25790 in 1997, and amaximum daily concentration of 2567 P/m3on 15th March 2000. The lowest annual index(647) corresponds to Cambrils, 2000, and thelowest maximum daily concentration (74P/m3) was registered on 7th April1996, in Manresa.The interannual variation of Platanuspollen values can be explained not only bymeteorological parameters and the endogenousfactors of the tree, but also by human activitysuch as elimination, pruning and watering.

Trifoliolate Leaves of Platanus bella (Heer) comb. n. from the Paleocene of North America, Greenland, and Asia and Their Relationships among Extinct and Extant Platanaceae

Trifoliolate leaves of Platanus bella (Heer) comb. n., a species previously known only from the Paleocene of western Greenland, are newly recognized from the Paleocene of northern Wyoming, U.S.A., and Altai of Xinjiang Province, northwestern China, indicating that the species was circumboreal in the early Tertiary. Epidermal anatomy preserved in specimens from all three areas confirms that these compound leaves belong to the Platanaceae. Platanus bella (Heer) comb. n. differs from modern species of Platanus but resembles the European Tertiary species Platanus fraxinifolia (Johnson & Gilmore) Walther and Platanus neptuni (Ettingshausen) Bůžek, Holý & Z. Kvaček, in the presence of large peltate glandular trichomes. We erect a new subgenus, Glandulosa, to accommodate P. bella, P. fraxinifolia, and P. neptuni. Each of these species possesses similar leaf epidermal structure, with the characteristic platanaceous stomatal apparatus and compound hair bases. In addition, the fossils bear peltate glandular trichomes on the epidermal surfaces that are not known among extant Platanus species. Reproductive structures linked to P. neptuni indicate that subgenus Glandulosa is properly placed in the Platanaceae but that it is a distinct clade from those of the extant subgenera Platanus and Castaneophyllum Leroy. We also review the status of the fossil genera Debeya and Dewalquea, to which some Cretaceous and Tertiary leaves of similar morphology have been placed, and reject the use of either of these names to accommodate leaves of subgenus Glandulosa.

Maceral and palynomorph facies from two tertiary peat-forming environments in the Powder River Basin, U.S.A.

The differences between the depositional settings of the Smith and Anderson subbituminous coal beds (Paleocene, central Powder River Basin, U.S.A.) are interpreted on the basis of their petrographic composition and palynologic assemblages. The Smith coal bed is relatively thin (< 5 m) and has a high degree of thickness variation (0–5 m) over short distances (< 8 km) , the result of deposition in an anastomosed fluvial environment where numerous lakes and small channels limited the extent of peat deposits. Although plants related to the living genus Glyptostrobus dominated the swamp, peat-forming plant communities contained mixes of ancestral species of Platanus and Ulmus as well as vegetation of lower stature such as Spagnum. Some intervals within the coal bed contain anomalously high concentrations of cell walls (humotelinite) and cell fillings (corpohuminite), some of which came from locally abundant, decay-resistant Pinaceae (or pinaceous) vegetation. Raised areas of the peat swamp characterized by Sphagnum were also favorable for the accumulation of carbonized plant components (inertinites). Because the peat of the Anderson coal bed formed on top of thick (> 50 m) sandstone bodies of an abandoned meander-belt complex, the coal bed is generally thicker (> 7 m) and more widespread (> 15 km) in extent than the Smith coal bed. The sands provided a relatively stable, poorly compactable platform that was favorable to the growth of large, arborescent vegetation, such as the dominant ancestral Glyptostrobus, as well as ancestral Nyssa, Carya, and Betulaceae in a well-drained but moist swamp environment. The stability of the peat-forming environment resulted in a raised peat deposit of relatively uniform paleoflora and peat composition. In the thicker areas of the Anderson coal bed, the upward increase in carbonized plant components indicates a progressively drier or better-drained swamp environment. Intervals within the coal bed that overlie or are lateral to crevasse-splay deposits contain a high concentration of pollen attributable to Pterocarya and an absence of carbonized plant remains, an indication that ancestral Pterocarya preferred a water-saturated environment close to the edge of the swamp where detrial influx occurred.

Flavonoids of fossil miocene Platanus and its extant relatives

Flavonoids of seven extant Platanus species and a fossil Platanus species from the Miocene Clarkia Flora of northern Idaho were compared. Sixteen flavonoids were isolated of which 15 were either wholly or partially identified. Flavonoids of Platanus are based on kaempferol and quercetin and most glycosides are linked at position 3. Because of an extremely high degree of overall chemical similarity and the presence of minor variation within some species, flavonoid data were of limited value in clarifying relationships among extant species. Flavonoid data suggest a closer chemical similarity of the fossil Platanus species to the Asiatic P. orientalis, rather than to the six investigated North American species. Morphologically, however, the fossil Platanus is very similar to P.occidentalis from eastern North America. These findings are similar to those reported in a paleobiochemical study of a fossil Liriodendron species from the same Miocene Flora.

Vegetative and Reproductive Morphology of an Extinct Plane Tree (Platanaceae) from the Eocene of Western North America

An extinct type of plane tree, common in the Middle to Late Eocene of Oregon, is reconstructed as a whole plant on the basis of repeated co-occurrence of isolated platanaceous organs at numerous localities. It is described in detail on the basis of leaf architecture, petiole and stem anatomy, pistillate inflorescence morphology, fruit anatomy, staminate inflorescence morphology, and in situ pollen morphology, rendering it the most completely documented fossil angiosperm species. The leaves, Macginitiea angustiloba (Lesq.) comb. nov., are relatively large, with five to seven palmately arranged lobes and palinactinodromous venation. They resemble those of some modern Platanus species except in features associated with a narrower angle between adjacent primary veins. The petioles are basally expanded and hollow and appear to have enclosed the axillary buds, as in most extant Platanus species. Inflorescences are borne as globose heads along separate staminate and pistillate axes. The pistillate inflorescenc...

Comparative anatomy of Platanus kerrii Gagnep.

The vegetative anatomy of Platanus kerrii Gagnep. Is described and compared with other Platanus species. Platanus kerrii is anatomically clearly a representative of Platanus but its xylem exhibits the