Search Results

You are looking at 1 - 10 of 22 items for

  • Author or Editor: Elisabeth A. Wheeler x
  • Search level: All x
Clear All
In: IAWA Journal
In: IAWA Journal

Inside Wood is an Internet-accessible wood anatomy reference, research, and teaching tool. The InsideWood database has coded wood anatomical descriptions based on the IAWA List of Microscopic Features for Hardwood Identification and is accompanied by a collection of photomicrographs. As of November 2010 there were over 5,800 descriptions and 36,000 images of modern woods, and over 1,600 descriptions and 2,000 images of fossil woods. CITES-listed timber species and other endangered woody plants are included in this digital collection hosted by North Carolina State University’s library. This web site has value in helping with wood identification because it has a multiple entry key that allows searching by presence or absence of IAWA features and it serves as a virtual reference collection whereby descriptions and images can be retrieved by searching by scientific or common name or other keywords.

Free access
In: IAWA Journal

The irreversibility of the major trends of xylem evolution, such as the origin of vessels in primitive angiosperms with long fusiform initials, and the shifts from scalariform to simple perforations and from tracheids to libriform fibres, has long been accepted by wood anatomists. Parallel development of these and other xylem features is generally accepted, and is suggested by the distribution patterns of the fibre and perforation plate type. Some recent phylogenetic analyses of seed plants suggest that there also have been some reversals in these general trends. The likelihood and extent of parallel origins and reversions of the major trends in xylem specialization are explored here by analysing a number of published hypotheses on the phylogenetic relationships within wood anatomically diverse major clades of angiosperms, and within some individual families. On the basis of these analyses, it appears that for these major Baileyan transformation series, parallelisms were more than twice as common as reversals. Functional adaptations to increased efficiency and safety of hydraulic architecture can largely explain the high incidence of parallelisms in xylem evolution.

Free access
In: IAWA Journal

Wood identification is of value in a variety of contexts - commercial, forensic, archaeological and paleontological. This paper reviews the basics of wood identification, including the problems associated with different types of materials, lists commonly used microscopic and macroscopic features and recent wood anatomical atlases, discusses types ofkeys (synoptic, dichotomous, and multiple entry), and outlines some work on computer-assisted wood identification.

Free access
In: IAWA Journal

Data on fossil dicotyledonous wood were assembled in order to 1) test the Baileyan model for trends of specialisation in dicotyledonous wood anatomy by addressing the question - were 'primitive' wood anatomieal features (as defined by the Baileyan model) more common in the geologie past than at present?, 2) infer, on a broad geographie scale, past climatie regimes, and long term climatic change, and 3) assess the extent of knowledge of fossil dicotyledonous woods. The resulting database has information on 91 anatomieal features for over 1200 fossil dicotyledonous woods. The incidence of selected anatomical features was plotted through time (by geologie epoch) for the world and for two regional groupings (roughly corresponding to the Laurasian and Gondwanan supercontinents). For comparison to the fossil wood record, the incidence of wood anatomie al features in the Recent flora was obtained from the 5260 record OPCN database for extant dicotyledonous woods.

Free access
In: IAWA Journal

A fossil wood with features similar to those of the Oligocene Hovenia palaeodulcis Suzuki (Rhamnaceae) from Japan is described from the late Eocene Florissant Fossil Beds National Monument, Colorado, U.S.A. This is the first report of fossil wood of this Asian genus in North America and is further documentation of Tertiary exchange between East Asia and North America. The affinities of Chadronoxylon florissantensis, the most common angiosperm wood at Florissant, are reevaluated; its combination of features suggests relationships with two families in the Malpighiales, the Salicaceae and Phyllanthaceae. Chadronoxylon is compared with Paraphyllanthoxylon Bailey. The Eocene P. hainanensis from China has notable differences from the original diagnosis of Paraphyllanthoxylon, but shares features with Chadronoxylon warranting transfer of P. hainanensis to Chadronoxylon and the creation of Chadronoxylon hainanensis (Feng, Yi, Jen) Wheeler & Meyer, comb. nov.

Free access
In: IAWA Journal

ABSTRACT

Angiosperm wood from the Miocene Landslip Hill silcrete, Southland, New Zealand is described. It is characterised by solitary vessels of two distinct size classes; rays of two size classes alongside aggregate rays; simple perforation plates; and axial parenchyma in tangential bands up to three cells wide. The wood has features similar to Casuarinaceae and is described here as a new species, Casuarinoxylon ildephonsi. The fossils were collected as isolated fragments of wood; there is no directly associated cladode or cone material although isolated fragments of these are common elsewhere in the Landslip Hill silcrete. This is the second record of fossil Casuarinaceae wood from New Zealand and the first sample to be anatomically described. Currently, Casuarinaceae does not occur in New Zealand. Casuarinoxylon ildephonsi would have grown in a warm temperate to subtropical climate on an open deltaic floodplain.

In: IAWA Journal

ABSTRACT

We revisited questions about changes in the incidences of functional wood anatomical traits through geologic time and compared the incidences of these traits in the fossil record with modern wood anatomical diversity patterns in order to test classical (“Baileyan”) and more recent ecophyletic hypotheses of xylem evolution. We contrast patterns through time for tropical and higher (paleo)latitudes. Data are from the InsideWood database. There are striking differences between woods from high and mid latitudes versus tropical (paleo)-latitudes. At temperate and subtropical latitudes (Laurasia and high latitude Gondwana), the epoch by epoch time series supports the Baileyan transformation series of vessel-bearing woody angiosperms (basal woody angiosperms and eudicots): “primitive” features such as scalariform perforations, exclusively solitary vessels, apotracheal diffuse parenchyma and heterocellular rays abound in the Cretaceous and become much less frequent in the Cenozoic, especially post-Eocene. In contrast, in the paleotropics hardly any changes occur in the incidences – each epoch has an equally “modern” spectrum of wood anatomical attributes. Although climatic gradients from the poles to the equator were less steep in the Cretaceous than in the late Cenozoic, the wood anatomical differences between mid-high latitude woods and tropical woods were much more pronounced in the Cretaceous than in later epochs. This seeming paradox is discussed but we cannot resolve it.

We suggest that tropical conditions have accelerated xylem evolution towards greater hydraulic efficiency (simple perforations), biological defense and hydraulic repair (elaborate paratracheal parenchyma patterns) as evidenced by late Cretaceous tropical latitude woods having near modern incidences of almost all traits. At higher paleolatitudes of both the Northern and Southern Hemisphere “ancestral” features such as scalariform perforations were retained in cooler and frost-prone regions where they were not selected against in mesic habitats because of lower demands on conductive efficiency, and could even be advantageous in trapping freeze-thaw embolisms. The fossil wood record remains too incomplete for testing hypotheses on the wood anatomy of the earliest angiosperms. The low incidence of so-called “xerophobic” woods sensu Feild with scalariform perforations with numerous (over 40) closely spaced bars in the Cretaceous tropical fossil record is puzzling. At higher paleolatitudes such woods are common in the Cretaceous.

Ring porosity, an indicator of seasonal climates and deciduousness, occurs at low levels in the Cretaceous and Paleogene at higher paleolatitudes only, and reaches modern levels in the Miocene. In Neogene and Recent temperate Northern Hemisphere, wide vessels are virtually restricted to ring-porous woods. In the tropics, there is a low incidence of ring porosity throughout all epochs.

The fossil record indicates that ecophysiological adaptation to tropical or temperate conditions was already evident in the Cretaceous with considerable latitudinal differences.

In: IAWA Journal

The wood anatomy offive genera of Magnoliaceae (59 native species, 2 introduced species) of China is described. Although the wood anatomy of this family is rather homogeneous, it is possible to identify most specimens to genus. Magnoliaceae wood from China is characterised by diffuse-porosity, scalariform to opposite vessel wall pitting, scalariform perforations with few bars or in some Magnolia species simple perforations, ground tissue fibres with distinctly to minutely bordered pits, marginal parenchyma and heterocellular rays mostly with one marginal row of square/upright cells. Intervessel and vessel-parenchyma pits are almost exclusively opposite in the Liriodendroideae; they are almost exclusively scalariform in the Magnolioideae, except for Magnolia section Rhytidospermum in which pits are predominantly opposite. Although the wood anatomical characters more or less overlap between Magnolia and Manglietia, these genera are wood anatomically distinguishable. Wood anatomy is similar in the evergreen species of Magnolia and Michelia. Kmeria is the only genus in which crystals were observed. Taxa from the tropics to subtropics tend to have longer and wider vessel elements, and a lower vessel frequency than those from temperate provenances; oil cells in rays mostly occur in the taxa from tropical and subtropical provenances. Simple perforation plates are mostly present in the temperate taxa. Counter to trends for the dicotyledons at large, helical thickenings are more common in tropical species than in temperate species, and, when present, are usually not distinct in deciduous species.

Free access
In: IAWA Journal