Inconspicuous Flowers Research Articles

Two New Species ofCleretum(Ruschioideae-Dorotheantheae, Aizoaceae) from the Northern Cape, South Africa

Two recently discovered members of the South African genus Cleretum N.E.Br. are described: C. bruynsii Klak and C. patersonjonesii Klak. Cleretum bruynsii occurs along the edge of the winter-rainfall region, between Namaqualand and Bushmanland in the Northern Cape, from north-east of Springbok to the north-eastern edge of the Kamiesberg. This species is characterized by inconspicuous yellow flowers on short pedicels. Its sister species, C. patersonjonesii, is endemic to the Kamiesberg in Namaqualand and possesses large yellow flowers on long pedicels. The two new species are closely allied to C. schlechteri and C. papulosum from which they differ by their more papillate, spoon-shaped leaves and the absence of a false septum in the fruits. A key to the 14 species of Cleretum is provided.

Phylogeny of the Dorotheantheae (Aizoaceae), a tribe of succulent annuals

AbstractDorotheantheae (Aizoaceae) is a small tribe of succulent annual herbs with flat leaves belonging to the generaAethephyllum, Cleretum and Dorotheanthus, which are endemic to the winter–rainfall region of South Africa. Several species are well–known for their conspicuous and striking flowers but others possess very inconspicuous flowers. Analysis of molecular data from combined plastid and nuclear sequences shows that Dorotheanthus is monophyletic while Cleretum is diphyletic, since the two species of Cleretum with lyrate leaves are most closely related to the vegetatively similar, monotypic Aethephyl–lum. In the absence of clear, diagnostic characteristics for separating Cleretum and Dorotheanthus, a revised classification for the Dorotheantheae is proposed in which the tribe consists of a single genus, Cleretum. Within Cleretum, we recognize 14 species, by raising/re–instating two subspecies to species rank and including two that are still undescribed. The major clades occupy distinct climatic and edaphic niches. Repeated shifting from large to small flowers may indicate changes in the breeding system. Since succulence in annuals is rare in the winter–rainfall region of southern Africa, we compare patterns of distribution between Dorotheantheae and the other leaf–succulent annuals in the region, namely in Mesembryanthemum (Aizoaceae) and in Crassula (Crassulaceae). We find that similar to the non–succulent annuals of the Poaceae and the Brassicaceae in this region, the annual species of Mesembryanthemum show a preference for arid areas. In contrast, in Dorotheantheae and in Crassula the hot–spots of diversity lie mainly in the wetter parts of the winter–rainfall area, with a decrease in the number of annual species northwards to the arid, winter–rainfall areas of the Richtersveld and the southern Namib.

Altitudinal variation in the reproductive performance of the Mediterranean shrub Rhamnus lycioides L.

Rhamnus lycioides L. subsp. Oleoides (Rhamnaceae) is a perennial shrub native to the Mediterranean Basin distributed along an altitudinal gradient, from sea level up to 1 000 m a.s.l. The specific goals of our study were (i) to compare plant morphology between two contrasting populations, (ii) to determine the reproductive system of R. lycioides, quantifying the relative importance of insects and wind as pollen vectors, (iii) to test if pollen limitation differs between populations, (iv) to study the main factors influencing fruit set and (v) to compare plant reproductive performance (mass allocation to flowers, fruits and seeds) between the two habitats. In the present study, we examined plant morphology and the reproductive performance of R. lycioides L. in contrasting environments in two populations located at the extremes of its altitudinal range in the island of Mallorca (Balearic Islands, Western Mediterranean Basin) along a 3-year period. Plant morphology, the relative importance of insects and wind as pollen vectors, the pollen limitation to seed production and the plant reproductive performance (mass allocation to flowers, fruits and seeds) were determined. Rhamnus lycioides individuals showed a higher plant surface/plant height ratio at the mountain than at the coast. This species appeared to be ambophilous despite its inconspicuous flowers, although the relative importance of wind as a pollination vector was higher at the mountain than at the coastal site. Fruit set was much higher at the mountain, where pollen appeared to be a limiting factor. By contrast, fruit set was not limited by pollen availability at the coastal population, where resource (water and nutrients) limitation seemed to be more determining. Flower size was greater at the coast, in contrast to fresh fruit weight that was higher at the mountain. Despite the relatively few differences between sites in precipitation patterns along the study period, water availability appeared to be the key factor explaining not only fruit set but also the reproductive performance of this species in the study populations.

The biology of flowering and structure of selected elements of Cornus alba L. flowers

The biology of flowering and the micromorphology of <i>Cornus alba</i> flowers were studied using light and scanning electron microscopy. The flowering of white dogwood in 2008 lasted 35 days, and the lifespan of a single flower was 3 days. The number of flowers per inflorescence was variable (on the average, it was 89). The largest group of insects visiting the flowers of <i>C. alba</i> comprised Hymenoptera (mainly bees and andrenids), then ants, dipterans and beetles. They foraged the dogwood flowers most intensively between 11.00 and 15.00. The inconspicuous four-petalled flowers of <i>C. alba</i> were characterised by the occurrence of T-shaped, two-armed non-glandular trichomes covering the receptacle as well as observed on the petals of the corolla, the style of the pistil and the anthers in a smaller number. The trichomes were covered by a thick cuticle with characteristic outgrowths. They contained a living protoplast, and plastids were observed in the cytoplasm of the trichome cells. In addition, anomocytic stomata were found in the epidermis of the receptacle and in the epidermis of the corolla petals. The stigma of the pistil and the adaxial epidermis of the petals were composed of very numerous conical papillae.

Sexual ratio and floral biology of the dioecious Neea theifera Oerst. (Nyctaginaceae) in a cerrado rupestre of central Brazil

Dioecy is characterized by a complete separation of sexual functions on male and female plants. It has evolved many times in flowering plants and is widespread among distinct Angiosperm families. It is viewed as a reproductive strategy to reduce endogamy, and to promote optimal resource allocation between male and female sexual functions. Neea theifera is a common species in Cerrado, neotropical savannas in Brazil, but information regarding its reproductive biology is still incomplete. In order to investigate how environmental conditions possibly affect this dioecious species, we studied its floral biology, sex ratio and spatial distribution of sexual morphs along a soil-altitudinal gradient. The sex ratio did not significantly deviate from the expected 1:1 ratio. However, flower abundance in the population was significantly biased towards staminate flowers. Female individuals were larger than male individuals and plant size was negatively correlated with altitude, but did not differ between sexual morphs. The population did not show spatial segregation of sexes and male individuals were sexually mature earlier than female ones. Staminate flowers were larger than pistillate flowers and presented high pollen viability. Meliponini bees, small flies and thrips were potential pollinators, but pollination success was very low. Dioecy in N. theifera corroborates many general features of this reproductive strategy, such as woody habit, inconspicuous flowers, pollination by small generalist insects and differential resource allocation between male and female plants. However, reproduction in this species seems to be impaired by pollinator limitation. The results showed that the soil-altitude gradient influenced the growth pattern of the species and may play an important role in its reproductive biology but did not affect dioecy directly.

Ecology of plant speciation

Ecology of plant speciation

Patterns of plant sexual systems in subtropical evergreen broad-leaved forests in Ailao Mountains, SW China

Aims Sexual systems influence many components of the ecology and evolution of plant populations and have rarely been documented in subtropical evergreen broad-leaved forests (SEBLF). Here we report frequency distribution and ecological correlates of plant sexual systems in SEBLF at Ailao Mountains, and compare our results with that of tropical and cool temperate forests. Methods We examine the sexual systems of 703 species of woody angiosperms belonging to 103 families and 296 genera based on a comprehensive survey of SEBLF at Ailao Mountains Natural Reserve. Information of plant sexual systems and ecological traits were mainly based on published literatures and specimens as well as our field observations. The associations between plant sexual system and ecological traits were assessed with chi-square tests. Important findings Among these species, 60.2% were hermaphroditic, 15.8% were monoecious and 24.0% were dioecious. The percentage of dioecious sexual system among tree species (22.2%) in SEBLF was comparable to those of tropical tree floras, but much higher than those of temperate forests at North America. The percentage of monoecious sexual system among tree species (30.1%) in SEBLF was higher than that of tropical tree floras, but much lower than those of temperate forests at North America. Monoecy was significantly associated with the tree growth form and was relatively common in temperate genera. Dioecy was significantly associated with fleshy fruits and monoecy was significantly associated with dry fruit type in SEBLF. The high percentage of diclinous sexual systems (monoecy and dioecy) in SEBLF may be associated with the origin of the flora and the prevalence of relatively small inconspicuous flowers of the forests in the Oriental Region.

Sexual Systems and Ecological Correlates in an Azonal Tropical Forests, SW China

ABSTRACTUnlike the seriate lowland rain forests in SE Asia, the tropical vegetation of Xishuangbanna (SW China) has developed in habitats with comparatively lower temperatures and precipitation. Consequently, although most of the families and genera of the flora are components of tropical ecosystems, many have reached their distribution limits in latitude. Selection pressures on sexual systems in these environments may be different from that experienced in lowland tropical regions. Here, we examine the sexual systems of 685 species of flowering plants belonging to 109 families and 356 genera based on 42 plots with a total area of 15.4 ha and compare our results with surveys of sexual systems from other tropical ecosystems. Among these species, 60.6 percent were hermaphroditic, 14.3 percent were monoecious, and 25.1 percent were dioecious. The percentage of dioecious sexual system among tree species (26.1%) was similar or higher than that of other tropical tree floras. Monoecy was significantly associated with the tree growth form and was relatively common in seasonal forest vegetation. Sexual systems involving unisexual flowers (dicliny) are particularly well represented in the tropical forests of Xishuangbanna accounting for 39.4 percent of all species surveyed. This pattern may be associated with the prevalence of relatively small inconspicuous flowers in the tropical forests of SE Asia and their correlation with diclinous sexual systems generally.

Savia bahamensis Maidenbush

This document provides an overview of Salvia bahamensis, commonly known as Maidenbush. It describes the plant as a large, evergreen shrub that can reach heights of 6 to 10 feet. The leaves are leathery and dark green, with small, inconspicuous flowers that bloom in the spring. Maidenbush is well-suited for use as a hedge or screen due to its dense foliage. It thrives in full sun to partial shade and is tolerant of a variety of soil types, including sandy and rocky soils. The document also includes information on propagation and maintenance, noting that Maidenbush is relatively pest and disease-free, making it a low-maintenance option for landscapes. Original publication date October, 1999.

Threatened Pollination Systems in Native Flora of the Ogasawara (Bonin) Islands

Various alien species have been introduced to the Ogasawara Islands (Japan). A survey was made investigating whether the native pollination systems fit an 'island syndrome' (biasing the flora to dioecy, with subdued, inconspicuous flowers) and whether alien species have disrupted the native pollination network. Flower visitors and floral traits were determined in the field (12 islands) and from the literature. Associations among floral traits such as sexual expression, flower colour and flower shape were tested. Among the 269 native flowering plants, 74.7 % are hermaphroditic, 13.0 % are dioecious and 7.1 % are monoecious. Classification by flower colour revealed that 36.0 % were white, 21.6 % green and 13.8 % yellow. Woody species (trees and shrubs) comprised 36.5 % of the flora and were associated with dioecy and white flowers. Solitary, endemic small bees were the dominant flower visitors and visited 66.7 % of the observed species on satellite islands where the native pollination networks are preserved. In contrast to the situation on the satellite islands, introduced honeybees were the most dominant pollinator (visiting 60.1 % of observed species) on the two main islands, Chichi-jima and Haha-jima, and had spread to satellite islands near Chichi-jima Island. The island syndrome for pollination systems in the Ogasawara Islands was evident in a high percentage of dioecious species, the subdued colour of the native flora and solitary flower visitors on satellite islands. The shape and colour adaptations of several flowers suggested native pollination niches for long-proboscis moths and carpenter bees. However, the domination and expansion of introduced honeybees have the potential for disruption of the native pollination network in the two main, and several satellite, islands of the Ogasawara Islands.

Aechmea pectinata: a hummingbird-dependent bromeliad with inconspicuous flowers from the rainforest in south-eastern Brazil.

The pollination biology of Aechmea pectinata (Bromeliaceae) was studied in a submontane rainforest in south-eastern Brazil. This species has a mainly clumped distribution and its aggregated individuals are likely to be clones. From October to January, during the flowering period, the distal third of its leaves becomes red. The inflorescence produces 1-15 flowers per day over a period of 20-25 d. The flowers are inconspicuous, greenish-white coloured, tubular shaped with a narrow opening, and the stigma is situated just above the anthers. Anthesis begins at 0400 h and flowers last for about 13 h. The highest nectar volume and sugar concentration occur between 0600 and 1000 h, and decrease throughout the day. Aechmea pectinata is self-incompatible and therefore pollinator-dependent. Hummingbirds are its main pollinators (about 90 % of the visits), visiting flowers mainly in the morning. There is a positive correlation between the number of hummingbird visits per inflorescence and the production of nectar, suggesting that the availability of this resource is important in attracting and maintaining visitors. The arrangement of the floral structures favours pollen deposition on the bill of the hummingbirds. Flowers in clumps promote hummingbird territoriality, and a consequence is self-pollination in a broader sense (geitonogamy) as individuals in assemblages are genetically close. However, trap-lining and intruding hummingbirds promote cross-pollination. These observations suggest that successful fruit set of A. pectinata depends on both the spatial distribution of its individuals and the interactions among hummingbirds.

Phylogenetic analysis of the ecological correlates of dioecy in angiosperms.

We report on a phylogenetic analysis of correlations between the occurrence of dioecy and several ecological and life-history attributes: tropical distribution, woody growth form, abiotic pollination, small inconspicuous flowers and inflorescences, many-flowered inflorescences and fleshy fruits. Various hypotheses have been proposed to explain why associations occur between dioecy and several of these attributes, yet most assume that dioecy originates more often in clades with these traits than in clades with alternative character states. To investigate correlations between dioecy and these attributes, and to provide insights into the potential evolutionary pathways that have led to these associations, we assigned states of these traits to genera on a large-scale molecular phylogeny of the angiosperms; we then used maximum-likelihood analysis to analyse the presence of correlations and the sequence of acquisition of traits. Phylogenetic analysis revealed correlations between dioecy and six of the seven attributes; only many-flowered inflorescences exhibiting no association with the dioecious condition. The particular correlations that were revealed and the strength of the association differed among the three main monophyletic groups of angiosperms (Rosids, Asterids, and Eumagnoliids). Our analysis provided no general support for the hypothesis that dioecy is more likely to evolve in lineages already possessing the seven attributes we considered. Further analysis of the intercorrelations of the seven attributes provided evidence for non-independence between some of the traits, implying that functional associations among these traits have influenced the ecology and evolution of dioecious species.

When looks can kill: the evolution of sexually dimorphic floral display and the extinction of dioecious plants.

Dioecious plants (with separate male and female individuals) more often have drab, inconspicuous flowers than related bisexual plants. Models indicate, however, that similar conditions favour the evolution of showy floral displays in dioecious and bisexual plants. One difference, however, is that dioecious plants may evolve floral displays that are sexually dimorphic. We show that males are more likely to evolve showy flowers than females in animal-pollinated plants, especially when pollinators are abundant. We demonstrate that this dimorphism places showy dioecious plants at a much higher risk of extinction during years of low pollinator abundance because pollinators may fail to visit female flowers. The higher extinction risk of showy dioecious plants provides an explanation for the fact that dioecious plants that do persist tend to have inconspicuous flowers and are more often wind pollinated. It may also help explain why dioecious plants are less species-rich than related bisexual plants.

Phylogeny, concerted convergence, and phylogenetic niche conservatism in the core Liliales: insights from rbcL and ndhF sequence data.

Calochortus and the family Liliaceae s.s. have often been considered each other's closest relatives, based partly on their shared possession of bulbs, visually showy flowers, winged wind-dispersed seeds, and narrow parallel-veined leaves. We present a well-supported molecular phylogeny for these groups and their close relatives in the core Liliales, based on sequence variation in the chloroplast-encoded rbcL and ndhF genes. This analysis identifies Liliaceae s.s. as monophyletic. including one clade (((Lilium, Fritillaris, Nomocharis), Cardiocrinum), Notholirion) that appears to have diversified in the Himalayas roughly 12 million years ago and another ((Erythronium, Tulipa), (Gagea, Lloydia)) that arose in East Asia at about the same time. Medeola and Clintonia are sister to Liliaceae s.s. and bear rhizomes, inconspicuous flowers, fleshy animal-dispersed fruits, and broad reticulate-veined leaves. Calochortus is sister to Tricyrtis; both Tricyrtis and the neighboring clade of Prosartes-Streptopus-Scoliopus share several of the traits seen in Medeola-Clintonia. The core Liliales thus provide compelling examples of both concerted convergence and phylogenetic niche conservatism. Invasion of open, seasonal habitats was accompanied by the independent evolution of bulbs, showy flowers, wind-dispersed seeds, and narrow parallel-veined leaves in Calochortus and Liliaceae s.s. Conversely, persistence in shady habitats was accompanied by the retention of rhizomes, inconspicuous flowers, animal-dispersed seeds, and broad reticulate-veined leaves in their sister groups. We advance arguments for the context-specific adaptive value of each of these traits, as well as evidence of parallel trends in other groups. Concerted convergence--convergence in several different traits, favored by the same shared set of ecological conditions, in two or more lineages--is an important evolutionary process that can mislead evolutionary analyses based solely on phenotypic variation.

Liana diversity and reproductive attributes in two tropical forests in Mexico

We describe liana diversity and variation in morphology of flowers and diaspores in two tropical forests in Mexico: a seasonally deciduous forest at Chamela, Jalisco and a lowland rain forest at Chajul, Chiapas. Flowers were classified as inconspicuous (≤1 cm in length and white or pale green flowers) or conspicuous (> 1 cm and brightly colored flowers). Dispersal syndrome was classified as anemochory, barochory, and zoochory. We recorded a higher number of lianas species in Chajul (128 spp.) than in Chamela (71 spp.). In both sites, families with the highest number of species were Bignoniaceae, Leguminosae, Sapindaceae, and Malphigiaceae, and almost half of the liana species had inconspicuous flowers. Most of the species had an abiotic syndrome of dispersal with 40 (56.3%) and 71 (55.5%) wind-dispersed species in Chamela and Chajul, respectively. Zoochory was significantly associated with inconspicuous flowers and anemochory with conspicuous flowers. Our results suggest that (1) flower morphology and dispersal type are not related with the amount of rainfall and (2) lianas are more prone to be wind-dispersed.

PHYLOGENY, CONCERTED CONVERGENCE, AND PHYLOGENETIC NICHE CONSERVATISM IN THE CORE LILIALES: INSIGHTS FROM rbcL AND ndhF SEQUENCE DATA

Calochortus and the family Liliaceae s.s. have often been considered each other's closest relatives, based partly on their shared possession of bulbs, visually showy flowers, winged wind-dispersed seeds, and narrow parallel-veined leaves. We present a well-supported molecular phylogeny for these groups and their close relatives in the core Liliales, based on sequence variation in the chloroplast-encoded rbcL and ndhF genes. This analysis identifies Liliaceae s.s. as monophyletic, including one clade (((Lilium, Fritillaris, Nomocharis), Cardiocrinum), Notholirion) that appears to have diversified in the Himalayas roughly 12 million years ago and another ((Erythronium, Tulipa), (Gagea, Lloydia)) that arose in East Asia at about the same time. Medeola and Clintonia are sister to Liliaceae s.s. and bear rhizomes, inconspicuous flowers, fleshy animal-dispersed fruits, and broad reticulate-veined leaves. Calochortus is sister to Tricyrtis; both Tricyrtis and the neighboring clade of Prosartes-Streptopus-Scoliopus share several of the traits seen in Medeola-Clintonia. The core Liliales thus provide compelling examples of both concerted convergence and phylogenetic niche conservatism. Invasion of open, seasonal habitats was accompanied by the independent evolution of bulbs, showy flowers, wind-dispersed seeds, and narrow parallel-veined leaves in Calochortus and Liliaceae s.s. Conversely, persistence in shady habitats was accompanied by the retention of rhizomes, inconspicuous flowers, animal-dispersed seeds, and broad reticulate-veined leaves in their sister groups. We advance arguments for the context-specific adaptive value of each of these traits, as well as evidence of parallel trends in other groups. Concerted convergence—convergence in several different traits, favored by the same shared set of ecological conditions, in two or more lineages—is an important evolutionary process that can mislead evolutionary analyses based solely on phenotypic variation.Corresponding Editor: D. Baum

Gossypianthus lanuginosus (Poir.) Moq. in A.DC. (Amaranthaceae) in Kansas

Specimens of cottonflower (Gossypianthus lanuginosus) were acquired in 1990 from southeastern Sumner County, Kansas. This acquisition documents a probable northward range extension of the otherwise widely distributed taxon. Plants were growing on salt-affected soils (slick spots), which supported little other plant life. Henrickson (1987) gives the general range of Gossypianthus lanuginosus as Oklahoma and Texas, southward into Mexico. The range given in the of the Great (Great Plains Flora Assoc., 1986) had the species (treated as Guilleminia lanuginosa (Poir.) Hook. L.) occurring in the western two-thirds of Oklahoma and Texas. On 13 October 1990, we acquired specimens of G. lanuginosus from Slate Creek Wetland (SCW) in southeastern Sumner County, Kansas (NW 1/4 SW 1/4 Sec 15, T33S, R2E, M.D. Proctor 467). This acquisition represented the northern-most known, the first report of the species in Kansas, and a probable range extension (Great Plains Flora Assoc., 1986; C. Freeman, Kansas Biological Survey, pers. comm., 1993). The species was collected from about 10 counties in Oklahoma based on holdings in the Bebb Herbarium, University of Oklahoma. The nearest locality for the species in Oklahoma was from Osage County, approximately 30 km southeast of SCW. Two varieties were reported to occur in Oklahoma, the typical variety and variety tenuiflorus (Hook.) Henrickson comb. et stat. nov (Henrickson, 1987). The specimens obtained at SCW were the typical varietyG. lanuginosus. A voucher specimen was deposited at the Elam Bartholomew Herbarium, Museum of the High Plains, Fort Hays State University. Additional specimens from SCW have been deposited at the herbaria of Southwestern College, University of Kansas, and University of Oklahoma. G. lanuginosus has been reported to occur in a variety of habitats including ' Present address: Oklahoma Biological Survey, 62 Elm Ave., Norman, OK 73019. This content downloaded from 207.46.13.169 on Sat, 01 Oct 2016 06:03:55 UTC All use subject to http://about.jstor.org/terms VOLUME 97, NUMBERS 1-2 65 stream valleys, dry sandy or rocky areas, prairies, open woodlands, and waste places (Great Plains Flora Assoc., 1986; Hendrickson, 1987). Our acquisition from SCW was from the Brewer complex, a silty clay loam with some salt-affected soils (slick spots) on the floodplain of Slate Creek, a tributary of the Arkansas River (Fenwick and Ratcliff, 1979). This habitat did not seem typical for the species because standing water was present for periods of time during the spring season of 1991 and 1992, often submerging the plants of Gossypianthus. We observed G. lanuginosus usually on slick spots, but this might have been an artifact of sparse vegetative cover on slick spots enhancing the visibility of G. lanuginosus. Associated species were Distichlis spicata (L.) Greene and Bouteloua gracilis (H.B.K.) Lag. ex Griff, both warm season grasses, and two species of Portulaca: P. olearacea L. and P. mundula I. M. Johnst. We suspected the range of this local population might have been expanding. On subsequent visits to SCW in August and October 1992, several specimens of G. lanuginosus were obtained more readily than our first acquisition in 1990. By 1992, the species was more well-represented and occurred over a larger area. We suspect the species will become established as a persistent member of the flora of the state, but there are some possible threats to its continued existence at this location. This population occurred on state-owned land (Kansas Department of Wildlife and Parks) that has been subjected to varying degrees of disturbance (e.g., drainage, flooding, burning), which could adversely affect this and other species. This population is the first to be reported for Kansas and care should be exercised to preserve it. Elsewhere G. lanuginosus has a wide distribution, thus it is probably in little danger. It is a relatively small plant with inconspicuous flowers, thus continued collecting will hopefully reveal a substantially larger range within

FLORAL BIOLOGY OF NEPENTHES GRACILIS (NEPENTHACEAE) IN SUMATRA

Nepenthes gracilis, a dioecious carnivorous plant, has inconspicuous flowers lacking petals. Nectaries distributed on the upper surface of four sepals secrete dilute nectar (3%–12% sugar concentration) at night, but the nectar immediately disappears during the day by evaporation in the sunny environment of Sumatra. Male flowers have a higher nectar production rate but lower sugar concentration of nectar than female flowers. Flowers of both sexes were visited by pyralid moths at night and by calliphorid flies in the evening. Pollen was found attached on these insects visiting Nepenthes flowers. The pattern of nectar production of sepals is regarded as attracting nocturnal flying insects and avoiding ants, while the pitchers attract ants by nectar secreted on the pitcher rim.

Floral Aroma: How Far Will Plants Go to Attract Pollinators?

relationships between plants and insect pollinators challenge biologists ross-pollination is the transfer of pollen from anthers where it is produced to a flower stigma on a different plant. The value of cross-pollination is that it promotes gene mixing and results in greater vigor in the offspring. Because crosspollination is riskier than self-pollination, flowering plants have evolved many ways of ensuring its success. Plants that let the wind carry their pollen indiscriminantly to distant ovules must produce copious amounts of pollen to correct for inaccuracy of delivery. These plants, however, need produce only small, inconspicuous flowers. Other plants use biological agents to deliver their pollen, but at a cost of advertising for and paying the agents. Floral aroma is one example of flower advertisement, and in some cases may even act as compensation for pollination services. Wind-pollinated flowers may not emit aromas, nor may bird-pollinated flowers that rely on vivid red colors, which appear black to many insects (Faegri and van der Pijl 1979, Heinrich 1979b, von Frisch 1967). The origin and function of floral aroma have been of recent interest. The fossil record is incomplete but shows that plants with flowerlike structures and insects capable of evolving into pollinators began their radiations at about the same time

Six New Species of Neotropical Lauraceae

Among recent collections of Lauraceae and older collections received on loan from various herbaria, several undescribed species were found. Six of those, Aiouea inconspicua van der Werff, Licaria bracteata van der Werif, Phoebe glabra van der Werif, Pleurothyrium costanense van der Werif, P. grandiflorum van der Werff, and P. westphalii van der Werff, are described. Difficulties with the generic placements of these new species are discussed. Lauraceae, comprising about 40 predominantly tropical genera, are rich in species in the Neotropics. The majority of the species have small, inconspicuous flowers. Genera are often hard to recognize and nearly all are in need of modem treatments. During identification of the large number of unidentified Lauraceae in MO and among the various loans I received, several undescribed species were found. Of those, the following six are here described as new.