Reproductive attributes of <Emphasis Type="Italic">Campanula</Emphasis> populations from Mt Olympos,Greece

We studied five reproductive attributes (fruit production and volume, seed content and weight, and seed germination) of different populations of Campanula species occurring along the elevation gradient of Mt Olympos, the highest mountain of Greece (2917 m), in order to examine whether and how they change with elevation, and if there are trade-offs among them. We also studied flower and fruit (reproductive) losses and population features in order to estimate whether there might be a threat to the survival of Campanula species on Mt Olympos. The genus is represented by nine species, ranging from cosmopolitan to steno-endemic. All species were found non-autogamous, and hence they depend on pollinators for their sexual reproduction. At the genus level, there is a trade-off between seed content per fruit and seed weight. At the species level, this is manifested only for C. glomerata, which produces the heaviest seeds, far exceeding all other species, and for C. spatulata, represented on Mt Olympos by two elevation distinct subspecies. Changes of the reproductive attributes are not continuous all along the elevation gradient at the genus level nor are they monotonic at the species level. Nevertheless, upland Campanula populations (≥1500 m) produce fewer fruits per individual, containing fewer but heavier seeds than lowland populations. This indicates a transition from ‘r’ to ‘K’ strategies, from low to high elevations, respectively. The patterns of change of reproductive attributes indicate prevalence of phylogenetic over environmental constraints. Laboratory tests showed that for many populations germinability is high at 15 °C, but there are both inter- and intraspecific differences regarding temperature optima. Ecotypic variation among populations of the same species at different elevations was evident; populations from higher elevations had lower optima and vice versa. Reproductive losses, ranging from zero to over 90%, occurred mainly at the stage of fruit maturation; grazing by sheep and goats was the usual cause. Though such losses might affect the short-lived species (the annual C. sparsa and the biennial C. lingulata), which depend entirely on fruit maturation and seed dispersal for their reproduction, there does not seem to be a serious threat to the survival of Campanula species on the mountain.     

Flowering phenology of Campanula on Mt Olynipos, Greece

We studied the fowering phenology of the genus Campanula (represented by nine species) along the elevation gradient of Mt Olympos (Greece) in order to assess whether there are elevation patterns at the genus level and whether these relate to patterns previously observed along such gradients at the community level. The traits examined were time and duration of the flowering period, flower life span, and duration of male and female flower phases. Floral attributes, such as number of flowers per plant, flower biomass, flower size, were also studied in order to examine whether they change with elevation or influence flower phenology. Flowering of Campanula species started in mid-May and ended in late September. The average duration of flowering of the genus was ca 27 d and the average floral longevity 4 d. In all but one species, the female phase lasted longer than the male. Campanula versicolor differed remarkably from all others in flower phenology and other floral trails. Nearly all Campanula populations studied had right or positively skewed flowering distributions indicating that flowering begins more abruptly than it ends. At the genus level, the time of flowering increased with elevation by 2 3d for every 100 m. Floral longevity also increased with elevation, by 0,2 d for every 100 m. Neither duration of flowering nor duration of the flower phases showed any consistent change with elevation. The same is true of the non–phenological floral traits examined. No trade–off between duration of flowering and flower life span or between structure and maintenance of flowers was apparent. The pattern of increasing floral longevity along the elevation gradient suggests a mechanism of compensation for reduecd pollinator availability.     

Pollination ecology of Campanula species on Mt Olympos, Greece

Nine Campanula species occurring along the elevation gradient of Mt Olympos were studied regarding their pollination ecology. The main issues considered were 1) the relative importance of various insect taxa as Campanula pollinators, 2) the patterns of pollinators' size and activity as a function of altitude, 3) the effect of pollinator exclusion on floral longevity, and 4) the extent to which the morphological difference of C. versicolor from the other Campanula species on Mt Olympos is expressed in its pollinating fauna. The vast majority of Campanula pollinators were solitary bees. Andrenidae and Megachilidae bees (mainly Chelostoma campanulorum) dominated the pollinating fauna of most species, Melittidae and bumblebees were the commonest pollinators of high altitude species. Campanula versicolor differs from the other Campanula species in that its corolla is not bell-shaped but flat. Mainly Apis mellifera, syrphid flies, and carpenter bees, unlike all other Campanula species on Mt Olympos pollinated it. At the species level, rather large altitudinal differences of Campanula populations did not result into large diversification of their pollinating fauna. The insect visitation rate to flowers decreased with altitude. When pollinators were excluded, the floral longevity of the species examined increased three to five times. Neither flower phase (male of female) was consistently favoured in the absence of pollinators. The pollen loads of the different insect taxa (Apis mellifera included) were of variable purity. The majority of Megachilidae bees carried pollen loads of high purity. Pollen loads from insects visiting Campanula species at high altitudes did not differ significantly in their purity from those visiting lowland species. The distribution of Campanula pollinators' body size along the altitudinal gradient exhibited a U-shaped pattern. No relationship was found between insect-pollinator body size and corolla size of Campanula species.     

北黄花菜的开花物候及传粉特性研究

北黄花菜是百合科萱草属的优秀观赏植物材料,也是进行品种创新的极有价值的野生种质资源。该研究对野生环境中北黄花菜的开花物候与传粉特性进行了连续三年的追踪观测,探讨其开花进程和传粉机制。结果表明:(1)北黄花菜种群的开花物候只有1个高峰期; 种群始花时间为5月末,盛花期为6月中旬,开花时间在30 d以上,单株花期为6～12 d; 开花同步性指数(S_i)分别为0.36、0.27和0.21,种群内个体开花时间重叠程度较低。(2)北黄花菜的开花数量与坐果数呈显著正相关(P<0.05),坐果数与单株花期长度呈极显著正相关(P<0.01),单株花期长度与始花时间呈显著负相关(P<0.05),表明北黄花菜开花数量越多,其坐果数越高。(3)北黄花菜的访花昆虫分属于4目10科共10种; 各访花昆虫的访花时间和行为区别较大; 主要的传粉昆虫有4种,其活动范围大,活动特点与北黄花菜午后开放的规律相匹配,能保证传粉效果; 部分访花昆虫虽然活动范围小,但可以帮助植物进行自花授粉; 两类访花昆虫的共同作用,使得北黄花菜的自然结实得到较大保障。上述结果可为北黄花菜的引种栽培和资源创新发挥实际作用。     

Flower morphology, phenology and visitor patterns in an alpine community on Mt Olympos, Greece

Alpine vegetation, restricted to the top of high mountains, is among the vegetation types most endangered by global warming, currently predicted to raise temperatures from 1.1 to 6.4 °C, by the end of the century. Nevertheless, background information allowing evaluation of impacts is rather scarce for some geographic zones. Our study of an alpine community on the Plateau of Muses (2600–2750 m a.s.l.) of Mt Olympos, the highest mountain of Greece, conducted in 1993–1994, can provide such background information for the Mediterranean region. We studied features relating to phenology of flowering, floral morphology, distribution and abundance, and flower visitors of plant species that exhibit a biotic pollination syndrome. We identified dominant patterns and we further (i) explored the relative contribution of the plant features and abiotic factors studied in explaining the activity patterns of flower visitors, (ii) examined if flower and visitor traits of the alpine community match each other according to the classical pollination syndromes, and (iii) investigated whether the responses of individual plant species to the yearly climatic variability result into phenological patterns that characterize the whole community. The common strategy of the alpine community was for early flowering and long flower life span; consistently early flowering species were twice as many as late flowering ones, whereas floral longevity (estimated for 36 species) averaged 5.2 days. Duration of flowering (estimated for 57 species) averaged 18.2 days. Climatic variability affected onset of flowering; all late flowering species delayed their flowering during the year characterized by a humid and cold summer. Duration of flowering and floral longevity did not change in a consistent way. Hymenoptera (Aculeates) were the dominant flower visitors. They accounted for 43.3% of the visits recorded, with bumblebees making a little less than half. Diptera followed making 37.5% of the visits (most made by syrphid flies). There was a mismatch between flower-morphology and flower visitor traits; the alpine community had predominantly non-specialized, pale-colour flowers, which are traits assumed to correspond to Diptera dominance and absence of social bees. Visitation was influenced by flower abundance and duration of flowering; proportionately more Diptera, and proportionately less Hymenoptera visited species with short flowering periods and few flowers present in the field. In a number of cases, the phenological and flower visitor patterns of the community of Mt Olympos deviated from those observed in other alpine environments suggesting a mediterranean influence even at high altitudes.     

Pollen production and circulation patterns along an elevation gradient in Mt Olympos (Greece) National Park

We studied airborne pollen along an elevation gradient of Mt Olympos (Greece). Samples were collected on a regular basis, over the period March–October 2009, in eight elevation-different stations, by use of a portable Hirst-type volumetric sampler. Concurrently, we studied pollen production in Quercus coccifera, Q. ilex, Pinus heldreichii and P. nigra, which are dominant species in the main vegetation types of the mountain. Of the 35 pollen taxa detected in the air, 18 account for 99.1 % of the total airborne pollen. These are the main pollen taxa each contributing by at least 0.5 %. Pinaceae (32 %) followed by Quercus (24 %) and Urticaceae (18 %) are the most abundantly represented taxa. Duration of the pollen season decreases with elevation by on average 3 days for every 100 m of elevation increase or by 5 days for every Celsius-degree of temperature decrease. Pollen concentration in the air decreases with elevation for the lowland taxa; with the exception of Cupressaceae, no pattern is observed for the other main taxa. The pine and oak species studied carry comparable amounts of pollen, approximately 10⁴ grains per flower, 10⁸–10⁹ per m² of crown surface and 10¹⁰–10¹¹ per individual; pollen production, primarily of the two Quercus species, is not responsive to environmental changes associated with elevation. Results provide evidence that, within a margin of error, airborne pollen reflects the distributions of pollen taxa on the mountain; regarding abundance, airborne pollen is representative of Quercus, but under-representative of Pinaceae. Ambrosia pollen is found at all elevations examined, although plants producing it have not been recorded on or around Mt Olympos.     

Pollination and breeding system of Eritrichium nanum (Boraginaceae)

 Flower development, pollination and breeding system of the high alpine cushion plant, Eritrichium nanum (Boraginaceae), were investigated in nine populations from the European Alps at altitudes of 2700 m–3200 m. Peak flowering period lasts longer than a month, from mid-June to the end of July. In contrast to statements in the literature that flowers are protogynous and nutlets remain in their calyx until spring we found a distinct protandry and nutlets being dispersed before mid-September. Various insects from 12 families, but mostly Diptera, frequently visited E. nanum flowers, with flies from the families Anthomyiidae and Muscidae being the predominant visitors. Under optimal conditions (max. solar radiation, min. wind force), visitation rates of 200 simultaneously observed flowers reached 32.5–46.7 insects per hour, i.e. 0.16–0.24 insects per flower per hour. However, the commonly observed Anthomyiidae and Muscidae clearly preferred the white-yellowish flowers of Saxifraga exarata and Saxifraga bryoides which are abundant at E. nanum sites and which are certainly also pollinated by species of these two fly families. The flowers of these Saxifraga species offer plenty of nectar and may compete for pollinators with E. nanum, when they are flowering in its proximity. However, various other insects like Pontia callidice and Psodos sp. (Lepidoptera) as well as Andrena sp. (Hymenoptera) and especially Eristalis tenax and closely related hoverflies showed a higher degree of flower constancy to E. nanum, often flying from a blue Eritrichium cushion to the next and hence causing outcrossing. The five fornices of E. nanum flowers which obstruct the tube containing stamens and nectar, are a feature which differs distinctly from the syndrome of fly-pollinated flowers with easily accessible nectar. Consequently pollination by flies in E. nanum seems to be caused mainly by the unfavorable ecological conditions at high altitudes, where flies are the most frequent insects. Bagging experiments showed that outcrossing and geitonogamy are the prevailing pollination modes, and autogamy, although possible, plays only a minor role. Received February 13, 2001 Accepted November 23, 2001     

Life history variation in a temperate plant invader, <Emphasis Type="Italic">Verbascum thapsus</Emphasis> along a tropical elevational gradient in Hawaii

Few studies have examined the life history of temperate plant invaders in the tropics. Temperate invaders that utilize seasonal cues to influence their life histories may be expected to behave differently in the tropics. This study examined variation in life history in an invading temperate weed, Verbascum thapsus, across an elevation gradient (1,690–2,720 m) along the montane and subalpine slopes of Mauna Kea, Hawaii. Over 7,000 seedlings were marked and monitored over a period of 3 years. Germination, survival, growth, and reproduction in V. thapsus varied among sites along the elevational gradient. Compared to plants at lower elevations, those at higher elevation sites (>2,000 m) had lower early seedling survival, higher established rosette survival, higher vegetative growth rates, higher threshold sizes for flowering, and commonly lived more than 3 years before flowering. The abundance of competing vegetation generally decreased with elevation, and this may drive variation in V. thapsus survival and growth. Size-dependent survival appears to play a major role in the selection for smaller size at first flowering and shorter generation time at lower elevations. This pattern is opposite to that reported in temperate mountains where high elevation plants flower sooner and at smaller size, but both patterns appear consistent with general life history theory for biennials. Due to novel biotic and climatic interactions in the tropics, predictions of growth patterns and invasion dynamics for temperate weeds in the tropics can be misleading when based on the plant’s behavior in temperate systems.     

Consequences of variation in flowering phenology for seed head herbivory and reproductive success in Erigeron glaucus (Compositae)

Summary We examined the relationship between flowering phenology, reproductive success (seed production only), and seed head herbivory for 20 similarly sized clones of Erigeron glaucus growing at Bodega Bay Reserve, northern California, USA. Although clones tended to reach peak flowering on the same date, they differed in the proportion of their total flowers produced around that date (flowering synchrony). Clones also differed in the number and density of flower heads presented at any one time to pollinators and herbivores (floral display). Both of these characteristics had consequences for herbivory and plant reproductive success. The proportion of flower heads damaged by insect herbivores was greater for clones that concentrated flowering activity during the main flowering period for the population as a whole (high synchrony) compared to clones that spread flowering out temporally. The primary reason for this result was that clones with low flowering synchrony produced a significant proportion of their flower heads during the fall and therefore, escaped attack by the tephritid fly, Tephritis ovatipennis. Clones with intermediate synchrony had lower seed success (total number of viable seeds produced over the year) than clones with either low or high synchrony. The proportion of flower heads damaged by insect herbivores and number of tephritid flies reared from flower heads were both negatively correlated to floral display while seed head mass and germination rates were positively related to display. Thus, clones which produced dense floral displays were favored both in terms of reduced herbivory and increased successful seed production.     

Flowering phenology and female fitness: impact of a pre-dispersal seed predator on a sexually polymorphic species

In order to produce seeds, animal-pollinated plants must flower synchronously with and be attractive to their pollinators while avoiding antagonists. Here, we explore temporal and inter-individual patterns in pollination and pre-dispersal seed predation of Dianthus sylvestris by Hadena moths, within and among three sex morphs. We scored plants that started flowering at different periods in 2001 and 2003 and found that fruit set decreased and predation rates increased over one season, and most of the other season, granting a female reproductive advantage to early flowering plants, though, we found no morph-specific temporal patterns. Female plants set more fruits, and more of their fruits escaped predation in one year, but this did not grant them a reproductive advantage since they produce fewer flowers per plant than the other morphs. Instead, mixed plants showed a clear female reproductive advantage. We also examined predation types by Hadena and seed production in attacked and intact fruits of individually marked flowers. Though female Hadena moths laid eggs preferentially into perfect flowers, flower sexes suffered similar predation by itinerant caterpillars. Attacked fruits contained fewer and lighter seeds than un-attacked ones. We conclude that pre-dispersal seed predation by Hadena may select on flowering onset of this sexually polymorphic species.     

On flower visitors and true pollinators: The case of protandrous Heracleum sphondylium L. (Apiaceae)

Hogweed (Heracleum sphondylium L.), a common European umbellifer, is very variable in terms of flower and inflorescence morphology. Its flowers are visited by numerous insects, yet little is known about the importance of the particular insect taxa. I observed umbels of two colour morphs (subspecies) of Heracleum sphondylium growing in NE Poland, which were visited by more than 108 insect species during two study seasons. Analysis of the insects' importance suggests that the most efficient pollinators are the medium-sized flies Eriozona syrphoides, and Lucilia spp. (Diptera). Bumblebees Bombus terrestris (Hymenoptera), beetles of genus Stenurella spp. and Dasytes spp. (Coleoptera) and flies Eristalis spp., Meliscaeva cinctella, Phaonia angelicae and Thricops nigrifrons also contribute to pollination of the studied plants, but their efficiency shows considerable seasonal variation. Although the dense umbels of the white flowered H. sphondylium subsp. sphondylium are generally more attractive for insect visitors than the loose yellowish inflorescences of H. sphondylium subsp. sibiricum, these taxa do not seem to attract different sets of the pollinators. For both subspecies, flowers in the staminate phase were visited significantly more often than those in the pistillate phase. Some flower visitors visited the staminate phase only, which suggests they may be parasites rather than pollinators.     

First record of the Australian psyllid Ctenarytaina spatulata Taylor (Homoptera: Psyllidae) in Europe

Abstract: The Australian species Ctenarytaina spatulata Taylor (Homoptera: Psyllidae) is reported from Europe for the first time. In August of 2002, it was recorded in several eucalyptus plantations in central Portugal. During August and September of 2002, the insect was apparently circumscribed to the area between rivers Douro and Tagus, being absent in the North and South of the country. In February of 2003, C. spatulata was already present all over the country and also in every place we inspected in Spain, namely in Galicia, Extremadura and Andalucia regions. The dispersion of the insect suggests that its introduction in Iberian forests is recent. At the moment, damages were observed in plantations located in northern and central Portugal, and also in the north of Spain. Predation on C. spatulata by spiders, green lacewings (Neuroptera, Chrysopidae), hoverflies (Diptera, Syrphidae, Syrphinae), ladybeetles (Coleoptera, Coccinellidae), and minute pirate bugs (Hemiptera, Anthocoridae) was observed in the field.     

Larger wildflower plantings increase natural enemy density,diversity, and biological control of sentinel prey,without increasing herbivore density

1. An important means of conserving beneficial insects in resource‐limited habitats is to meet their ecological requirements, which may be achieved by providing areas containing flowering plants that bloom throughout the season, but little is known about the importance of wildflower plot size for supporting natural enemies or the biological control they provide. 2. Wildflowers were established in plots of sizes ranging from 1 to 100 m², and found that natural enemy density, group richness, and diversity of natural enemy groups increased with plot size. 3. The density of insect herbivores was lower in all flower plots than in the control samples, whereas the diversity of herbivore groups was significantly higher in flower plots. 4. Comparing population growth of sentinel soybean aphids (Aphis glycines Matsumura) among plot sizes, aphid colonies were smaller as plot size increased. 5. Providing beneficial insects with flowering resources resulted in significantly more natural enemies and greater pest control than in smaller flower plots or mown grass areas. 6. These results indicate that the density, diversity, and function of natural enemies are sensitive to the size of wildflower plantings, even at relatively small scales. Therefore, larger wildflower plots are more suitable for the conservation of beneficial insects and their provision of natural pest control.     

Phenotypic selection on flowering phenology and size in two dioecious plant species with different pollen vectors

Dioecious plants may be pollinated biotically by animals or abiotically via wind or water currents. It has been hypothesized that these two types of pollen vectors might impose contrasting selective pressures on plant flowering phenology. In the present study we describe the flowering phenology of two sympatric dioecious species with contrasting pollination modes: Mercurialis perennis (wind‐pollinated) and Tamus communis (insect‐pollinated). We estimated selection differentials and gradients for flowering time and flowering synchrony. As flowering time might depend on the accumulation of enough internal resources, we also estimated direct and indirect selection on plant size. Both species have male‐biased sexual ratios, and males are bigger and produce larger flower displays than females, but only in T. communis do males bloom earlier and for longer than females. Selection gradients suggest that selection tends to favor early‐flowering females of T. communis. There is no evidence of direct current selection on the flowering phenology of M. perennis. Intersexual differences in phenology fit with sex allocation and sexual selection theories. As we hypothesized, phenology of the animal‐pollinated species is under stronger selection than that of the wind‐pollinated species and we discuss the potential role of pollen vectors in shaping the flowering phenologies of the study species.     

Indirect interaction between two native thistles mediated by an invasive exotic floral herbivore

Spatial and temporal variation in insect floral herbivory is common and often important. Yet, the determinants of such variation remain incompletely understood. Using 12 years of flowering data and 4 years of biweekly insect counts, we evaluated four hypotheses to explain variation in damage by the Eurasian flower head weevil, Rhinocyllus conicus, to the native North American wavyleaf thistle, Cirsium undulatum. The four factors hypothesized to influence weevil impact were variations in climate, weevil abundance, phenological synchrony, and number of flower heads available, either on wavyleaf thistle or on the other cooccurring, acquired native host plant (Platte thistle, Cirsium canescens), or on both. Climate did not contribute significantly to an explanation of variation in R. conicus damage to wavyleaf thistle. However, climate did influence weevil synchrony with wavyleaf flower head initiation, and phenological synchrony was important in determining R. conicus oviposition levels on wavyleaf thistle. The earlier R. conicus was active, the less it oviposited on wavyleaf thistle, even when weevils were abundant. Neither weevil abundance nor availability of wavyleaf flower heads predicted R. conicus egg load. Instead, the strongest predictor of R. conicus egg load on wavyleaf thistle was the availability of flower heads on Platte thistle, the more common, earlier flowering native thistle in the sand prairie. Egg load on wavyleaf thistle decreased as the number of Platte thistle flower heads at a site increased. Thus, wavyleaf thistle experienced associational defense in the presence of flowering by its now declining native congener, Platte thistle. These results demonstrate that prediction of damage to a native plant by an exotic insect may require knowledge of both likely phenological synchrony and total resource availability to the herbivore, including resources provided by other nontarget native species.     

COMPARATIVE REPRODUCTIVE BIOLOGY OF HERMAPHRODITIC AND MALE-STERILE IRIS DOUGLASIANA HERB. (IRIDACEAE)

A comparative study of the reproductive biology of male-sterile and hermaphroditic plants in a gynodioecious population of Iris douglasiana Herb. (Iridaceae) was conducted at the University of California's Marine Laboratory at Bodega Bay, California, between 1976–1979. Each year of the study, there were 11.1% male-sterile plants in the population, some of which began blooming at the same time as the earliest blooming hermaphrodites. Male-sterile flowers made up between 7–21% of the flowers produced during the male-sterile flowering period. Male-sterile flowers had smaller sepals and petals than hermaphrodites, there were fewer of them per square meter, and they had fewer pollinated stigmas than did hermaphroditic flowers. In a test to determine pollinator preference, intact hermaphroditic flowers tended to have more pollinated stigmas than did hermaphrodites with their stamens removed or those flowers with shortened sepals made to resemble the smaller male-sterile flowers. Floral phenology and nectar-flow patterns were similar in both types of flowers as were the kinds of amino acids and sugar rewards in the nectar. Male-sterile flowers, however, produced much less nectar per flower. There were no significant differences in the number of ovules per flower or the number of seeds produced per capsule between the two flower types, but the loss of seeds through larval predation was much greater in capsules from hermaphroditic flowers. Early flowering and setting of seed by plants with male-sterile flowers could give them a reproductive advantage over plants with hermaphroditic flowers which experience higher levels of larval predation later in the growing season.     

Flower heliotropism in an alpine population of Ranunculus acris (Ranunculaceae): effects on flower temperature,insect visitation,and seed production

Some plants in arctic and alpine habitats have heliotropic flowers that track the sun. This results in a heating of the flower's interior, which may improve the possibilities for insect pollination and seed production. Here, I examine whether flower heliotropism in an alpine population of the self-incompatible Ranunculus acris L. (Ranunculaceae) enhances pollinator visitation and seed production. Flowers of Ranunculus acris tracked the sun during the day. Tracking accuracy was greatest during the middle of the day. The temperature elevation in flowers was negatively correlated with the flower's angle of deviation from the sun. Despite the increased temperature, insects did not discriminate among flowers on the basis of their angle of deviation from the sun, or tend to stay longer in the flowers aligned closest towards the sun. A tethering experiment was conducted on three groups of plants flowering at different times in the 1993 season and on one group the following season. Manipulation plants were constrained not to track the sun, whereas control plants tracked the sun naturally. Solar tracking had no effect on seed:ovule ratio, seed mass, or abortion rate in any of the groups. There is probably a very narrow range of weather conditions (cold, sunny, and calm) where flower heliotropism may enhance visitation rate to flowers and their seed production.     

Spatial variation in selection in a plant-pollinator system in the wadis of Sinai,Egypt

We studied an insect-plant pollination system in adjacent steep-sided wadis and a connecting plain in the mountains of southern Sinai (Egypt): this environment creates a strongly divided habitat, which may promote the local differentiation of sub-populations. We tested for spatial differences in phenotypic reproductive characters of the only plant flowering abundantly in early spring, Alkanna orientalis (Boraginaceae), and its major pollinator at that time of year, Anthophora pauperata (Apoidea, Anthophoridae). There were significant morphological differences between sub-populations of Alkanna, mainly between plants from the narrower wadis and those on the interconnecting plain. Flowers on the plain were larger, with wider corollas and more nectar standing crop; these plants retained more flowers on the inflorescence, but received many fewer visits to flowers. There was a significant selection gradient between flower size and maternal fitness (seed set) in the plain, but not elsewhere. Natural selection may have increased resources devoted to attracting insect visitors in response to fewer pollinating visits in the plain. Consistent with this explanation, by experimentally manipulating flower number per plant, we showed that within a wadi having more flowers on a plant secured more visits.     

Factors affecting the development of Botrytis cinerea (grey mould) on linseed (Linum usitatissimum) buds, flowers and capsules

A key was produced to describe 10 stages of development of linseed buds, flowers and capsules. Botrytis cinerea conidia germinated more rapidly and germ tubes grew longer on linseed stigmas, petals and mature senescing capsules than on green leaves, sepals and immature capsules. The proportion of conidia which germinated increased and the germ tubes continued growing for longer in the presence of linseed pollen and flower petal extracts. In controlled environment and field experiments, the response of buds, flowers and capsules to inoculation with B. cinerea changed with stage of development; few pre‐flowering buds developed symptoms (brown lesions, then grey mould), but high proportions of flowering and post‐flowering buds did so. Few immature green capsules developed symptoms and the proportion of capsules which developed symptoms increased as they matured. The presence of linseed pollen decreased the incubation period from inoculation with spore suspensions to appearance of B. cinerea symptoms on buds. A disease cycle was produced to suggest the changes in susceptibility of linseed to infection by B. cinerea conidia during bud, flower and capsule development.