Drip Tips Research Articles

Multi-inspired Janus fabrics with asymmetric coolmax patterns for rapid sweat diffusion and effective sweat-shedding

Janus fabrics with unidirectional liquid transport property have attracted wide attention for their ability to remove excess sweat and lower skin temperature. However, most Janus fabrics face the sweat removal issue on their outer surface when the sweat absorption capacity of their hydrophilic surface reaches limit, which inevitably slows down one-way sweat transport rate and induces the fabrics to become heavy/clingy. Herein, inspired by natural Namib Desert beetles and drip tips, circular Coolmax patterns (severed as sweat extraction points near the skin) and triangular Coolmax patterns (severed as sweat removal zones on the outside of the fabric) are asymmetrically sewn on superhydrophobic cotton fabrics to enable continues one-way sweat transport and allow effective sweat diffusion/shedding on its outer surface. During the sweat transporting and evaporation process, a large amount of heat is dissipated. As a result, the created Janus fabrics can maintain human body temperature about 1.3 ℃ lower than the conventional cotton fabric. Moreover, the low adhesion (∼0.2 mN cm−2) between the wet skin and the fabric makes wearers feel more comfortable. The method can be potentially used for the large-scale commercial production of Janus fabrics and provide insights for the development of smart fabrics in the future.

Characterization of the Components and Functional Properties of a Plasma-Derived Fibrin Sealant

Background The activity and purity of Fibrin Sealant Grifols are described in this article. This fibrin sealant contains two components (fibrinogen and thrombin) that mimic the final stages of clotting. Fibrin sealants are primarily used as an adjunct to hemostasis for mild to moderate surgical bleeding in adults when standard surgical techniques are ineffective or impractical. Objective The aim of these studies was to assess the biochemical and functional characteristics of Fibrin Sealant Grifols. Methods Total protein, plasma protein impurities, and molecular forms were analyzed for both components. Clottable fibrinogen and thrombin activity were also measured. Both components were analyzed by SDS-PAGE and Western blot. The fibrin sealant clot was functionally characterized. Results The components had minimal contamination by other plasma proteins and no aggregates or degradation products. The fibrinogen component was almost completely clottable fibrinogen. The thrombin component contains albumin. The fibrinogen component formed a fibrin polymer and clots with tensile strength similar to literature values. The application device applied the components in a 1:1 volume ratio. Clotting time was ∼ 5 s when applied with the drip tip and nearly instantaneous when applied with the airless spray apparatus. Conclusion This fibrin sealant was shown to contain highly purified fibrinogen and thrombin delivered in a 1:1 volume ratio. These properties contribute to the clinical safety and efficacy of this product for many applications.

Leaf morphological traits as adaptations to multiple climate gradients.

Leaf morphological traits vary systematically along climatic gradients. However, recent studies in plant functional ecology have mainly analysed quantitative traits, while numerical models of species distributions and vegetation function have focused on traits associated with resource acquisition; both ignore the wider functional significance of leaf morphology.A dataset comprising 22 leaf morphological traits for 662 woody species from 92 sites, representing all biomes present in China, was subjected to multivariate analysis in order to identify leading dimensions of trait covariation (correspondence analysis), quantify climatic and phylogenetic contributions (canonical correspondence analysis with variation partitioning) and characterise co‐occurring trait syndromes (k‐means clustering) and their climatic preferences.Three axes accounted for >20% of trait variation in both evergreen and deciduous species. Moisture index, precipitation seasonality and growing‐season temperature explained 8%–10% of trait variation; family 15%–32%. Microphyll or larger, mid‐ to dark green leaves with drip tips in wetter climates contrasted with nanophyll or smaller glaucous leaves without drip tips in drier climates. Thick, entire leaves in less seasonal climates contrasted with thin, marginal dissected, aromatic and involute/revolute leaves in more seasonal climates. Thick, involute, hairy leaves in colder climates contrasted with thin leaves with marked surface structures (surface patterning) in warmer climates. Distinctive trait clusters were linked to the driest and most seasonal climates, for example the clustering of picophyll, fleshy and succulent leaves in the driest climates and leptophyll, linear, dissected, revolute or involute and aromatic leaves in regions with highly seasonal rainfall. Several trait clusters co‐occurred in wetter climates, including clusters characterised by microphyll, moderately thick, patent and entire leaves or notophyll, waxy, dark green leaves. Synthesis. The plastic response of size, shape, colour and other leaf morphological traits to climate is muted, thus their apparent shift along climate gradients reflects plant adaptations to environment at a community level as determined by species replacement. Information on leaf morphological traits, widely available in floras, could be used to strengthen predictive models of species distribution and vegetation function.

First fossil evidence of Hylodesmum palaeoglutinosum from India and comments on its extinction from the subcontinent

ABSTRACT We report for the first-time well-preserved leaflets of Hylodesmum palaeoglutinosum from the latest Neogene sediments (Rajdanda Formation: Pliocene) of Jharkhand, eastern India. Macromorphological features show that the fossil leaflet remains are identical to those of modern endemic taxon H. glutinosum (Muhl. ex Wild.) Ohashi & Mill (tribe: Desmodieae, subfamily: Papilionoideae; family: Fabaceae). This is the first authentic record of the occurrence of leaflets comparable to H. glutinosum from the Cenozoic sediments of India, and even worldwide. At present H. glutinosum does not grow in India, nor Southeast Asia, but is restricted to North America. Analysis of these fossil remains with respect to the modern distribution pattern of H. glutinosum and the physiognomic characters (including acuminate “drip tips”) of the fossil leaflets suggests that a tropical evergreen forest was growing under a warm, humid climate at the time of deposition. This interpretation agrees with earlier published qualitative climate interpretations for the area, and our recently published quantitative climatic data obtained from the study of leaf remains recovered from the same formation. Here, we discuss the possible causes of disappearance of this fabaceous taxon from the present-day vegetation of Chotanagpur Plateau area, eastern India and also comment on its extinction in India. The disappearance may be related to the gradual intensification of rainfall seasonality since the Pliocene.

Trade-off relationship between light interception and leaf water shedding at different canopy positions of 73 broad-leaved trees of Yangji Mountain in Jiangxi Province, China

<p indent=0mm>As light interception and leaf water shedding may require different leaf traits, trade-offs may exist between the leaves’ abilities in light interception and leaf water shedding. Moreover, such trade-offs may vary with the vertical canopy position as leaf traits vary with tree height. We studied the variations in leaf traits at different canopy positions to study how canopy positions would affect the trade-off between the traits related to light interception and leaf water shedding in subtropical broad-leaved trees. We used the standardized major axis regression method to analyze the relationships among leaf morphological traits (leaf thickness and leaf length/width ratio), configuration traits (leaf angle and leaf drip tip length), and physiological traits (photosynthesis-light saturation point and photosynthesis-light compensation point) between sun and shade leaves. The results are as follows: (i) There was no significant difference in the leaf thickness and leaf length/width ratio at different canopy positions (<italic>P</italic>>0.05). The leaf angle (34.92°±1.15°), light saturation point ((954.89±27.86) µmol/(m²·s)), and light compensation point ((29.45±1.02) µmol/(m²·s)) at the upper canopy were significantly higher than those at the lower canopy (leaf angle: 16.66°±0.50°, light saturation point: (520.74±15.47) µmol/(m²·s), and light compensation point: (12.54±0.38) µmol/(m²·s); <italic>P<</italic>0.05). However, the leaf drip tip length was significantly shorter at the upper canopy position ((4.26±0.15) mm) than at the lower canopy position ((7.18±0.22) mm; <italic>P</italic><0.05). (ii) There were significant correlations among leaf angle, leaf drip tip length, light saturation point, and light compensation point at different canopy positions (<italic>P</italic><0.05), but the leaf drip tip length and leaf length/width ratio were only weakly correlated at the upper canopy leaves (<italic>P</italic><0.05). (iii) Common slope (<italic>P</italic>>0.05) and isometric scaling existed among the leaf angle, light saturation point, and light compensation point at different canopy positions, but there was no common constant (<italic>P</italic><0.05). These results indicated that the canopy position does not alter the trade-off strategy between light interception and leaf water shedding. The leaf drip tip length and inclination were mainly affected by the light saturation point and light compensation point.

A plot-based elevational assessment of species densities, life forms and leaf traits of seed plants in the south-eastern Himalayan biodiversity hotspot, North Myanmar

ABSTRACT Background : Species density along elevation gradients often shows hump-shaped patterns, but in-depth data for Myanmar is still not available. Aim : The first plot-based study to detect the elevational patterns of life forms and tree leaf traits, and their relation to environmental factors in Myanmar. Methods : All seed plant species were recorded on 76 plots between 400 and 4100 m. Regression models were used to identify the variables with highest predictive power for species densities of different life forms and leaf traits. Results : Species density showed a linear elevational decline except for grasses (increase) and epiphytes (hump-shaped pattern) and were related to temperature and precipitation in all considered life forms. Tree leaf size, the proportion of species with simple leaves and leaves with drip tips decreased with elevation, while the proportion of toothed leaves increased. Conclusions : Our data partly confirm some widely held assumptions about elevation patterns in species density and leaf traits. While the climatic dependence behaves as expected, leaf traits and lifeforms show mixed and sometimes surprising patterns. Previous knowledge of these patterns is partly confirming, but highly scattered regionally, so our study performed in one region offers a rare opportunity towards a natural history image of a biodiversity hotspot..

&lt;p&gt;&lt;strong&gt;&lt;em&gt;Magnolia poqomchi&lt;/em&gt;, a new species of subsection &lt;em&gt;Magnolia &lt;/em&gt;(Magnoliaceae) from San Cristóbal Verapaz, Alta Verapaz, Guatemala&lt;/strong&gt;&lt;/p&gt;

In the last decade, several species of magnolias have been described for Guatemala, five of which are found in Alta Verapaz, where, during an exploratory survey, we found a specimen that did not correspond morphologically to any previously reported species. To obtain material and determine phenology, several individuals were monitored for a year. Here, we describe this as a new species of Magnolia subsection Magnolia (Magnoliaceae). It is distributed in the cloud forest of San Cristóbal Verapaz, Alta Verapaz, and is culturally important for the local villagers. It differs from other similar species, M. montebelloensis and M. tribouillierana, in having an abruptly acuminate leaf apex (drip tip), larger flowers, purple staminophores and more stamens, among other traits. According to IUCN criteria, M. poqomchi is critically endangered [B1ab (iii), B2ab (iii)]. Additionally, we include a dichotomous key and distribution map for the genus in Guatemala. Taking this record into account, there are a total of ten native species reported for Guatemala, making it an important centre of species diversity for magnolias.

Miocene flora from the Siwalik of Arjun Khola area, Nepal and its palaeoclimatic and phytogeographic implications

An extensive study on the plant fossils (leaf and fruit impressions/compressions) collected from the Miocene of Siwalik sediments, Arjun Khola area, western Nepal has been carried out. It revealed the existence of a variety of angiosperm plant taxa represented by 43 genera and 47 species belonging to 24 families. Of these, 34 species are reported for the first time from the studied area. Quite a number of fossils out of the entire lot, were described much prior to the present study from other represented by the Siwalik localities. Most of the leaf and fruit specimens are assignable to families of dicots but a single fossil leaf Clinogyne Salisb. has been assigned to the monocot family Marantaceae. The families which are highly represented in the assemblage are Fabaceae, Sapindaceae, Dipterocarpaceae and Annonaceae. Fabaceae which appeared in Upper Paleocene became a major component of the evergreen forest during middle Miocene. A majority of the families are generally represented by leaf forms but Sindora Miq. and Butea Roxb. ex Willd. of the Fabaceae and Terminalia L. of the Combretaceae are represented by fruits. Most of the fossil leaves in the assemblage showed large to medium size with drip tips, entire margins and apparent greater venation density. All the above characters collectively indicated the existence of tropical to sub–tropical type of vegetation during the Miocene all along the Himalayan foot hills of Nepal. Out of the identified specimens, the majority (more than 69%) resembled modern taxa, distributed in the tropical evergreen forests of different geographical regions of the world and recovery of similar looking fossil elements from the Arjun Khola area, indicated existence of similar forest types in and around the area at the time of Siwalik sedimentation. In contrast, the present day vegetation in and around the area is quite different from the past as it includes elements that generally constitute plants of dry deciduous forests. A number of plants migrated from south–east Asia to India via Myanmar and vice–versa. Consequently, many taxa, especially members of Dipterocarpaceae and Fabaceae, existing in south–east Asia in the Paleogene appeared on the Indian subcontinent and Nepal in the Neogene. Phytogeographical data also suggests that taxa flourishing in the Himalayan foot–hills during Siwalik sedimentation have migrated elsewhere in modern times possibly towards south and southeast in search of favourable conditions for luxuriant growth.Present day distribution of all the recovered species from the Siwalik Foreland Basins of Arjun Khola area shows that they are found today in the tropical forests of North–east India, Bangladesh, Myanmar and Malaysia where favourable climatic conditions exist and only little amount of taxa are found to grow presently in the Himalayan foothills. Thus, it may infer that a fair change in floral composition has taken since the Miocene. The nearest living relative (NLR) method of palaeoclimate construction suggests that the Arjun Khola area enjoyed a tropical climate having Mean Annual Temperature (MAT) 22–28ºC and Mean Annual Precipitation (MAP) 2200–3200 mm during the deposition of the sediments.

Variation in leaf wettability traits along a tropical montane elevation gradient.

Summary Leaf wetting is often considered to have negative effects on plant function, such that wet environments may select for leaves with certain leaf surface, morphological, and architectural traits that reduce leaf wettability. However, there is growing recognition that leaf wetting can have positive effects.We measured variation in two traits, leaf drip tips and leaf water repellency, in a series of nine tropical forest communities occurring along a 3300‐m elevation gradient in southern Peru. To extend this climatic gradient, we also assembled published leaf water repellency values from 17 additional sites. We then tested hypotheses for how these traits should vary as a function of climate.Contrary to expectations, we found that the proportion of species with drip tips did not increase with increasing precipitation. Instead, drip tips increased with increasing temperature. Moreover, leaf water repellency was very low in our sites and the global analysis indicated high repellency only in sites with low precipitation and temperatures.Our findings suggest that drip tips and repellency may not solely reflect the negative effects of wetting on plant function. Understanding the drivers of leaf wettability traits can provide insight into the effects of leaf wetting on plant, community, and ecosystem function.

Rhaphiostylis minima Jongkind (Icacinaceae), a new liana species from Ivory Coast &amp; Liberia

A new species of Rhaphiostylis, R. minima sp. nov. from Liberia and Ivory Coast, is described and illustrated here. It is characterised by its comparatively small size, an ovate to lanceolate leaf blade with long drip tip and a partly glabrous ovary that is in shape in between those of R. elegans Engl. and R. preussii Engl. Rhaphiostylis elegans is lectotypified and illustrated here.

Trade-offs between light interception and leaf water shedding: a comparison of shade- and sun-adapted species in a subtropical rainforest

Species in high-rainfall regions have two major alternative approaches to quickly drain off water, i.e., increasing leaf inclination angles relative to the horizontal plane, or developing long leaf drip tips. We hypothesized that shade-adapted species will have more pronounced leaf drip tips but not greater inclination angles (which can reduce the ability to intercept light) compared to sun-adapted species and that length of leaf drip tips will be negatively correlated with photosynthetic capacity [characterized by light-saturated net photosynthetic rates (Amax), associated light compensation points (LCP), and light saturation points (LSP)]. We tested this hypothesis by measuring morphological and physiological traits that are associated with light-interception and water shedding for seven shade-adapted shrub species, ten sun-adapted understory shrub species, and 15 sun-adapted tree species in a subtropical Chinese rainforest, where mean annual precipitation is around 1,600 mm. Shade-adapted understory species had lower LMA, Amax, LSP, and LCP compared to understory or canopy sun-adapted species; their leaf and twig inclination angles were significantly smaller and leaf drip tips were significantly longer than those in sun-adapted species. This suggests that shade-adapted understory species tend to develop pronounced leaf drip tips but not large leaf inclination angles to shed water. The length of leaf drip tips was negatively correlated with leaf inclination angles and photosynthetic capacity. These relationships were consistent between ordinary regression and phylogenetic generalized least squares analyses. Our study illustrates the trade-offs between light interception and leaf water shedding and indicates that length of leaf drip tips can be used as an indicator of adaptation to shady conditions and overall photosynthetic performance of shrub species in subtropical rainforests.

LEAF MORPHOLOGICAL CHARACTERISTICS OF SOME UNDERSTOREY SPECIES IN A SRI LANKAN LOWLAND RAIN FOREST

Variations in leaf morphological characters were studied among tree seedlings of fourunderstorey species grown in shade houses (full sun and shade) in the Sinharaja lowland rainforest over a one-year period from January 2000 to January 2001. Study species were Psychotrianigra, Geartnera vaginans, Byrsophyllum el/ipticum (Rubiaceae) and Agrostistachisintramaginalis (Euphobiaceae). All are understorey specialists and Byrsophyl/um ellipticum,Agrosttstachis intramaginalis are endemic to Sri Lanka. Measurements of leaf area, length ofdrip tip, petiole length, petiole diameter, fresh weight, and margin length were taken and specificleaf area was calculated. The greatest specific leaf area and margin length values were recordedfor all species in shade while smallest values were in full sun. In contrast the greatest leaf freshweight of these species were observed in fullsun. Petiole length of Psycho/ria nigra, Geartneravaginans, and Byrsophyllum ellipttcum was highest the greatest in shade and for Agrostistachisintramaginalis it was highest in full sun. The greatest length of drip tip and leaf area values wererecorded in shade and petiole diameter in full sun for Psycho tria nigra and for Byrsophyllume//ipticum. For other two species, length of drip tip and Jeaf area values were the greatest infullsun and petiole diameter in shade. A significant difference (p&lt;=0.05) was found on specificleaf area between sun and shade for all species except Agrostistachis intramaginalis. Leaf area,margin length or drip tip showed no significant. The results indicate that these understoreyspecialists showing similar morphological characteristics when grown in shade and in fullsun intheir early seedling stage. Studied two genera has differed by specific lead area than othermorphological characters. Continuation of this study with other leaf ontogenic characters isimportant to understand the variation of understorey species

MORPHOLOGICAL CHARACTERISTICS OF LEAF OF DIFFERENT DEVELOPMENT STAGES OF LATE SUCCESSIONAL CANOPY TREE SPECIES IN A SRI LANKAN LOWLAND RAIN FOREST

This study examined the morphological characteristics of four development stages of fourcanopy species belong to two families that have been characterized as late successional.Variations in leaf morphological characters were studied among seedlings (50 cm inheight), saplings (2 - 5.5 m height), pole size (15 - 20 m height) and mature trees (&gt;25 mheight). Two species belong to family Clusiaceae tMesua ferrea, Mesua nagassarium) andtwo species belong to the family Dipterocarpaceae (Shorea worthington ii, Shoreamegistophylla). Sample leaves were collected from Sinharaja, a forest located in thesouthwest lowland wet zone of Sri Lanka. Morphological characters measured were leafarea, leaf length, leaf width and length of drip tip. To study these characters tenindividuals were taken for each development stage of a species. Three leaves were sampledfrom an individual and leaf length, leaf area, leaf width and length of drip tip weremeasured for each leaf.Data were analysed using a one way ANOV A and Tukey's studentised range to determinedifferences among development stages at 5% significance level. Results indicate thatsaplings of all species had the highest leaf area, leaf length and leaf width. Seedlings hadthe highest length of drip tip.This study revealed that there are morphological variations within a species of latesuccessional canopy tree species

Cordiera longicaudata sp. nov. and Duroia valesca sp. nov. of the Alibertia group (Gardenieae–Rubiaceae)

Two neotropical species of the Alibertia group (Gardenieae–Rubiaceae) are described and illustrated. Cordiera longicaudata C. Persson &amp; Delprete sp. nov. occurs in Panama and northwestern Ecuador (Awá Reserve) and is characterized by its long drip tips and glabrous to minutely puberulent corollas. Duroia valesca C. Persson &amp; Delprete sp. nov. is from the Atlantic forest of Brazil (states of Espírito Santo and Minas Gerais) and is distinguished by its heteromorphic calyx lobes that are large, 13–15×7–8 mm, elliptic and contorted in female flowers, whereas the calyx lobes of the male flowers are 3–5×1–2 mm and narrowly triangular.

Angiospermous fossil leaves from the Siwalik foreland basins and their palaeoclimatic implications

The angiospermous fossil leaves so far recorded from the Siwalik foreland basins of India, Nepal and Bhutan have been analysed and an attempt has been made to deduce palaeoclimate and phytogeography of the region during Siwalik (Mio-Pliocene) Period. The physiognomic characters of the fossil leaves have been critically examined in order to infer the climate of the region. The leaf features that have used mainly an aid in determining past climate, are leaf margin, drip tips, leaf size and venation density. The dominance of entire margined species (about 92%) in the Siwalik leaf assemblage indicates the prevalence of tropical climate. The presence of conspicuous drip tips and other features like leaf size, leaf texture, nature of petiole and venation density collectively suggest tropical climate with heavy rainfall (MAT 28°-29° and MAP 308 mm) during Mio-Pliocene. Almost all the fossil leaves recovered from different fossil localities in the Himalayan foreland basins have been identified with the modern angiospermous taxa up to specific level. From the present day distribution of these comparable species it is evident that most of the comparable species of the fossil assemblage are not found at present in the foot hills and became extinct due to unfavourable climatic condition after Mio-Pliocene. Moreover, on the basis of habit and habitat of comparable taxa of angiospermous fossil leaves it has been concluded that the Siwalik flora consists of three types of constituents in the forest during the sedimentation of Siwalik foreland basins: (1) Evergreen (2) Evergreen and Moist deciduous (3) Mixed deciduous. The Siwalik leaf assemblage is dominated by evergreen constituents like dipterocarps, legumes and other associated taxa in contrast to mixed deciduous constituents of the present day floral assemblage of the regions. This is most probably due to post-Pliocene orogeny of the Himalaya which brought changes in the topography and climate and thus adversely affecting the vegetation scenario of the Himalayan foot hills.

Tree species composition and diversity of tropical mountain cloud forest in the Yunnan, southwestern China

AbstractSpecies composition, physiognomy, and plant diversity of the less known cloud forests in Yunnan were studied based on data collected from 35 sample plots at seven sites. In floristic composition, the cloud forests are mainly comprised of Fagaceae, Ericaceae, Vacciniaceae, Aceraceae, Magnoliaceae, Theaceae, Aquifoliaceae, Illiciaceae, Lauraceae, and Rosaceae. Physiognomically, the forests are dominated by tree and shrub species. Lianas are rare in the forests. The plants with microphyllous or nanophyllous leaves comprise 44.32–63.46% of the total species, and plants with an entire leaf margin account for more than 50% of the tree and shrub species. There are few tree and shrub species with a drip tip leaf apex and papery leaves. Evergreen species make up more than 75% of the total tree and shrub species. In a 2,500 m2 sampling area, the number of vascular species ranged between 57 and 110; Simpson's diversity index ranged from 0.7719 to 0.9544, Shannon–Winner's diversity index from 1.8251 to 3.2905, and Pielou's evenness index from 0.5836 to 0.8982 for trees. The cloud forests in Yunnan are physiognomically similar to the tropical cloud forests in America and Southeast Asia. They very much resemble the mountain dwarf mossy forest in Hainan Island, southeastern China, and the Mountain ericaceous forests in the Malay Peninsula. The cloud forests in Yunnan are considered to be developed, as are the tropical upper montane cloud forests in Asia.

Adaptive function of drip tips: a test of the epiphyll hypothesis in Psychotria marginata and Faramea occidentalis (Rubiaceae)

Drip tips are thought to resist the growth of epiphyllous fungi, lichens, bryophytes and algae on leaf surfaces by promoting the drainage of water following rain. This hypothesis was tested by altering the tip of one leaf in each of 50 pairs of opposite leaves on plants of each of two woody species in the understorey of Barro Colorado Island, Panama. After 11 mo in situ, there were no statistical differences between the mean epiphyll cover on leaves with and leaves without drip tips. Epiphyll cover was, however, strongly correlated between the opposite leaves at a node, even though one had a drip tip and the other had the tip removed. This correlation could be due to small-scale heterogeneity of insolation, temperature and humidity in the crowns of plants. A relationship between epiphyll cover and growth of the branch containing the leaves provides qualitative support for this interpretation. It seems clear that drip tips do not have a large, consistent, easily detectable effect on epiphyll cover. However, because of the tiny cost of drip tips, reductions in epiphyll growth that are small and transitory and occur in only a portion of a plant's leaves may provide sufficient advantage to explain the evolution of drip tips. No experiment to date has been capable of detecting such effects.

South American palaeobotany and the origins of neotropical rainforests

Extant neotropical rainforest biomes are characterized by a high diversity and abundance of angiosperm trees and vines, high proportions of entire-margined leaves, high proportions of large leaves (larger than 4500 mm2), high abundance of drip tips and a suite of characteristic dominant families: Sapotaceae, Lauraceae, Leguminosae (Fabaceae), Melastomataceae and Palmae (Arecaceae). Our aim is to define parameters of extant rainforests that will allow their recognition in the fossil record of South America and to evaluate all known South American plant fossil assemblages for first evidence and continued presence of those parameters. We ask when did these critical rainforest characters arise? When did vegetative parameters reach the level of abundance that we see in neotropical forests? Also, when do specific lineages become common in neotropical forests? Our review indicates that evidence of neotropical rainforest is exceedingly rare and equivocal before the Palaeocene. Even in the Palaeocene, the only evidence for tropical rainforest in South America is the appearance of moderately high pollen diversity. By contrast, North American sites provide evidence that rainforest leaf physiognomy was established early in the Palaeocene. By the Eocene in South America, several lines of evidence suggest that neotropical rainforests were diverse, physiognomically recognizable as rainforest and taxonomically allied to modern neotropical rainforests. A mismatch of evidence regarding the age of origin between sites of palaeobotanical high diversity and sites of predicted tropical climates should be reconciled with intensified collecting efforts in South America. We identify several lines of promising research that will help to coalesce previously disparate approaches to the origin, longevity and maintenance of high diversity floras of South America.

Eocene-Oligocene extinction and paleoclimatic change near Eugene, Oregon

Thick ash-fl ow tuffs provide marker beds through fossiliferous Eocene and Oligocene marine and non-marine sedimentary rocks near Eugene, Oregon. New mapping, radiometric dating, and paleomagnetic stratigraphy of these tuffs and rocks now allow dating of local fossil fl oras. The Comstock, Goshen, Rujada, and Willamette fl oras have been widely used as evidence for Eocene-Oligocene climatic cooling and drying. Eocene leaves from Comstock and Hobart Butte included such thermophilic taxa as Liquidambar. The early Oligocene Goshen fl ora lacked Liquidambar but retained many thermophilic species with large leaves that have entire margins and acuminate apices (drip tips). In contrast, fossil leaves from later Oligocene Rujada and Willamette fl oras are small and serrate, and most lack drip tips. Marine faunas also indicate climatic cooling and local disappearance of thermophilic molluscs such as Anadara, Ficus, and Conus. Our dating and compilation of plant and molluscan fossil occurrences indicate a steady rise in species diversity from 46 Ma to maximal diversity of thermophilic taxa at 35‐34 Ma, then extinctions of 60% of plant species after 33.4 Ma and 32% of marine invertebrates after 33.2 Ma, both signifi cantly postdating the Eocene-Oligocene boundary at 33.7 Ma. Plant diversity rebounds during the early Oligocene, but marine invertebrates continue to decline into the Oligocene in part due to the retreat of fully marine environments from the Eugene area. Neither these data, nor evidence from coeval fossil plants and soils in central Oregon, support the notion of a “Terminal Eocene Event,” nor any other single, abrupt paleoclimatic shift or extinction. The Eocene-Oligocene biotic and climatic transition was drawn out over some 6 m.y. Abrupt forcings such as meteorite impacts or volcanic eruptions are less likely explanations for cooling and diversity decline than long-term processes such as mountain building, changing ocean currents, or reorganization of the carbon cycle by coevolution of grasses and grazers.

Evidence for an in situ early Paleocene rainforest from Castle Rock, Colorado

A very diverse, early Paleocene (63.8 ± 0.3 Ma) fossil leaf site located in Castle Rock, Colorado represents nearly autochthonous burial of a rainforest floor. This is an unusual fossil flora preserved in an unusual manner. The site, on the western margin of the Denver Basin in synorogenic sediments associated with the rise of the Laramide Front Range, is dated using multiple methods. Leaves are preserved in three distinct units overlying a poorly developed paleosol that contains in situ tree trunks. Fossil-bearing units are continuous along 150 m of outcrop. The leaves were apparently preserved as a result of rapid deposition of sand and mud onto the floor of a mature rainforest via overbank flooding. Five quarries were excavated and the leaves from these quarries were segregated by morphotype and scored for leaf area and margin type. From 1030 specimens, we document 93 unique dicotyledonous angiosperm leaf types, three cycads, three ferns, two conifers, and seven seed types. There is little taxonomic variation among leaf-bearing units of a single quarry, but the taxonomic composition varies significantly among laterally spaced quarries, suggesting that the fossil leaf litter reflets the original growth positions of the source trees. We compare the fossil leaf litter to leaf litter of modern forests and show that the Castle Rock flora has numerous features in common with extant equatorial rainforests, including dominance by angiosperms, high species richness, large leaves that often have smooth margins and drip tips, and high spatial heterogeneity from quarry to quarry.