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An infestation of parkinsonia (Parkinsonia aculeata) located on Alexandria Station, Northern Territory, Australia, was successfully treated with a bioherbicide using stem-implanted capsules. The bioherbicide (Di-Bak Parkinsonia®), containing three endemic endophytic fungi (Lasiodiplodia pseudotheobromae, Macrophomina phaseolina and Neoscytalidium novaehollandiae), is the first Australian registered woody weed bioherbicide. The product was effectively administered to the plant stems using a mechanical device, resulting in the subsequent development of a dieback event. After a period of establishment, it progressed through an adjacent untreated population, resulting in a significant decline in infestation vigour and preventing recruitment from the seedbank. This is the first report of large-scale management of parkinsonia by this method.

Parkinsonia aculeata and Prosopis juliflora are two of the most problematic invasive plant species in the Brazilian tropical seasonal dry forest, but the mechanisms driving the biological invasion of this ecosystem is virtually unknown. This study assessed the role of arbuscular mycorrhizal symbiosis, in particular of Funneliformis mosseae, on the biological invasion process by P. aculeata and P. juliflora. F. mosseae is a cosmopolitan arbuscular mycorrhizal fungus (AMF) frequently found in association with plants of different regions of the world. The present study was conducted to determine if F. mosseae is present in the soils from two invaded areas by P. aculeata and P. juliflora and to evaluate its contribution to the growth of these invasive plant species. Firstly, AMF colonization and AMF spore abundance was assessed in the roots and rhizosphere of both species in the field. Spores of F. mosseae were obtained from the soil samples and used to set up a greenhouse experiment to evaluate its effect on plant dry biomass and plant phosphorus concentration for both exotic plant species. We found that F. mosseae inoculation promoted the growth of the invaders and lead to a higher P concentration. Our results demonstrate that (a) AMF play an important role in the biological invasion process of the Brazilian tropical seasonal dry forest by P. aculeata and P. juliflora and (b) F. mosseae might be an important AMF species during the biological invasion process.

Plant-soil feedback is recognized as the mutual interaction between plants and soil microorganisms, but its role on the biological invasion of the Brazilian tropical seasonal dry forest by invasive plants still remains unclear. Here, we analyzed and compared the arbuscular mycorrhizal fungi (AMF) communities and soil characteristics from the root zone of invasive and native plants, and tested how these AMF communities affect the development of four invasive plant species (Cryptostegia madagascariensis, Parkinsonia aculeata, Prosopis juliflora, and Sesbania virgata). Our field sampling revealed that AMF diversity and frequency of the Order Diversisporales were positively correlated with the root zone of the native plants, whereas AMF dominance and frequency of the Order Glomerales were positively correlated with the root zone of invasive plants. We grew the invasive plants in soil inoculated with AMF species from the root zone of invasive (I changed) and native (I unaltered) plant species. We also performed a third treatment with sterilized soil inoculum (control). We examined the effects of these three AMF inoculums on plant dry biomass, root colonization, plant phosphorous concentration, and plant responsiveness to mycorrhizas. We found that I unaltered and I changed promoted the growth of all invasive plants and led to a higher plant dry biomass, mycorrhizal colonization, and P uptake than control, but I changed showed better results on these variables than I unaltered. For plant responsiveness to mycorrhizas and fungal inoculum effect on plant P concentration, we found positive feedback between changed-AMF community (I changed) and three of the studied invasive plants: C. madagascariensis, P. aculeata, and S. virgata.

In Australia, several well-established invasive plant species have experienced unexplained dieback. To investigate this issue, we used internal transcribed spacer (ITS) amplicon pyrosequencing to characterise fungal communities within stems (endophytes) and soils associated with dieback-affected and healthy plants from populations of five exotic invasive species (Jatropha gossypiifolia, Mimosa pigra, Parkinsonia aculeata, Tamarix aphylla and Vachellia nilotica) across northern Australia. M. pigra and P. aculeata were sampled from multiple geographic regions. A total of 353 and 4926 fungal operational taxonomic units (OTUs) were identified in stem and soil samples, respectively. Members of Ascomycota were common, representing 75% of stem and 49% of soil OTUs. Four common endophytes, including Cladosporium perangustum, were at least 50% more prevalent in healthy than dieback-affected samples for the five invasive species combined. Fungal community structure within stem and soil samples varied among invasive species. For the two species sampled across multiple regions, M. pigra had similar fungal communities within stems among regions, but a significant difference in associated soil fungi, suggesting that host plant rather than environment determined endophytic communities in this species. Irrespective of the invasive species and sample type (stem vs. soil), no significant differences were observed in fungal richness, diversity or community structure between dieback-affected and healthy plants, either locally or regionally. Our work failed to identify fungi that were either unique or relatively more abundant in dieback than healthy plants in these invasive species. Future investigations of biotic factors other than fungi, such as bacteria, archaea and oomycetes, may provide more insights into the mechanism of the dieback phenomenon affecting these species.

The search for generalizations in the face of complex species–environment interactions is particularly important for minimizing the cost of managing populations of species. We tested whether we could generalize, at various nested scales, the species‐level demography of the widely invasive plant species Parkinsonia aculeata (Fabaceae) and whether these generalizations were representative of the demography observed locally. Full demographic surveys at all life stages of the species were conducted in 23 Australian sites during seven years (from 2000 to 2007), across a 1000‐km climatic gradient. Sites were nested across four climate regions (arid, semi‐arid, semi‐wet/dry tropics, wet/dry tropics) and three habitat types (upland, wetland, and riparian). We estimated the vital rates (growth/retrogression, survival, fecundity) at all life stages and size classes and combined them to create 99 site–year demographic matrix population models. With these models, we then estimated site–year‐specific asymptotic population growth rates and their corresponding prospective elasticity values to perturbation of the vital rates. We then developed a nested retrospective elasticity analysis (nested LTRE) to test whether and how upscaling the results (i.e., from site to habitat, to climate region, and to the invaded range) produced averaging bias, which could lead to spurious interpretations of the relationships between the retrospective elasticity values. The prospective analysis highlighted that site–year variation in the matrix population models, population growth rates, and corresponding elasticities could not be well summarized by a single species‐level analysis and that the spread was as diverse as found in previously reported multispecies‐level demographic analyses. The nested LTRE analysis showed that upscaling demographic models introduced for most sites new sources of errors in the estimation (in terms of magnitude and sign of retrospective elasticities), which increased drastically as we progressively aggregate the demographic information between nested scales of observation. Our findings suggest that regardless of the scale, demographic generalizations at the species scale are not always useful for managing P. aculeata across sites in its invaded range, given its plasticity in demography.

Quantifying survey completeness is a key step in designing and interpreting biodiversity assessments. To date this has only been examined either at a local scale through repetitive sampling, or across broader geographic areas through multiple survey sites. In this paper, we determine the completeness of sampling at both local and continental scales, of the phytophagous arthropod assemblage on the Neotropical shrub Parkinsonia aculeata (Leguminosae). We used survey gap analysis (SGA) to determine whether existing surveys adequately sampled the diversity of environments and geographic space covered by the plant. Within defined geographic regions, we determined survey completeness at a local scale with species accumulation curves. SGA identified the highest priority sites for future sampling in the Sonoran Desert and the Pacific Coast of South America. The arthropods sampled on P. aculeata differed significantly between seasons, highlighting the importance of including surveys throughout the year. At the local scale, surveys in most regions were estimated to have sampled

The effect of 6 host plant species [Mangifera indica L., Cajanus cajan (L.) Millspaugh, Coffea arabica L., Cucurbita moschata Duchesne, Parkinsonia aculeata L., and Ficus benjamina Roxb.], on bionomics of the mango mealybug Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae) was studied in the screenhouse. Biological and life table parameters of the mealybug differed significantly among the host plants. Developmental period (egg to adult) was shortest on M. indica (23.5 days and 25.3 days for females and males, respectively), whereas it was longest on F. benjamina (33.0 days and 37.3 days for females and males, respectively). The egg to adult female survivorship was highest on C. moschata (79.6%) and lowest on C. arabica (30.9%). Fecundity was highest on C. moschata (811.3 egg/female) followed by M. indica (716.8 egg/female). The sex ratio was female-biased on C. moschata, M. indica, C. cajan and P. aculeata. Adult mealybug longevity also varied with host plant for both mated and unmated fe...

Plants of Parkinsonia aculeata L. were dehydrated by withholding water for 13 days and then rehydrated. The leaves of control plants and stressed plants were analyzed every four days from the beginning of stress and 6, 24, and 48 h after stress relief. Analysis of leaf water status showed a decrease in relative water content of nearly 16% during dehydration and a return to its control value after 48 h of rehydration. The contents of chlorophylls, chloroplast lipids (monogalactosyldiacylglycerol and digalactosyldiacylglycerol), and neutral lipids increased by 38%, 20%, and 125% (in μg·mg dry mass−1), respectively, when the daily decrease of relative water content reached 1.4%, while the mass of extra-plastidial lipids (phosphatidylcholine and phosphatidylethanolamine) increased by 25% (in μg·mg dry mass−1) only when the daily water loss was 2.6%. In addition, incorporation of radioactive acetate in lipids showed a preferential synthesis of digalactosyldiacylglycerol, phosphatidylglycerol, and phosphatidylcholine. The unsaturation degree of galactolipids remained stable, while a slight increase of unsaturation of phosphatidylcholine and phosphatidylethanolamine was observed. After rehydration, the mass of chlorophylls fell sharply, while the amount of total lipids decreased slowly as the level remained 17% higher than in the control 6 h after stress relief. Our results show that Parkinsonia plants are sensitive to a slight variation of the water potential and respond with an increased synthesis of membrane lipids during stress and after rehydration.

A new species is described from Argentina: Eueupithecia vollonoides sp. n. and a differential diagnosis from E. cisplatensis Prout, 1910 is given. The genus Eueupithecia Prout, 1910 (Sterrhinae), so far having been retained to be monotypic, includes two species now.

Aim To develop and test a general framework for estimating weed invasion potential (suitability and susceptibility) that utilized expert knowledge of dispersal, establishment and persistence and considered the influence of land management. Location The semi-arid Desert Channels Region of Queensland, Australia (476,000 km2). Methods We developed a general framework that integrated knowledge and empirical data of the environmental and land management variables influencing the dispersal, establishment and persistence of the invasive shrub parkinsonia (Parkinsonia aculeata) using a Bayesian network linked to a Geographic Information System (GIS). We evaluated the influence of different land management scenarios on landscape suitability for parkinsonia. Model performance was assessed by comparing predicted landscape suitability with mapped parkinsonia locations and estimated parkinsonia density. Results Our predictions of moderate to high suitability corresponded reasonably well with mapped parkinsonia locations (71% match) and areas of common to abundant estimated density (92% match). They also suggested that parkinsonia has not reached its potential distribution within the study region. Under current land management conditions, 77,000 km2 of land was found to be highly or moderately suitable for parkinsonia. Scenario analysis indicated that maintaining moderate herbaceous ground cover levels, and using sheep to browse juvenile parkinsonia, reduced the predicted moderate to high suitability area to 27,000 km2, offering a potential management strategy for limiting parkinsonia invasion. Main conclusions Weed invasion potential can be reasonably estimated using expert knowledge of dispersal, establishment and persistence, integrated using a Bayesian network linked to a GIS. This modelling approach can be an alternative to process-based and phenomenological modelling, which can be problematic for modelling new and emerging weed invasions, particularly where data are patchy. The modelling approach also allows the influence of land management change on invasion potential to be investigated through scenario analysis.

The study was conducted at the Awash National Park (ANP) Ethiopia, todocument Invasive Alien Species (IAS) and to assess the spread of Prosopis juliflora (Sw.) DC. A total of 64 sample plots were laid systematically along the altitudinal gradient of 750 to 1916 m.Potential IAS were recorded. IAS which may threaten biodiversity of the park includes species such as Prosopis juliflora, Parthenium hysterophorus L., Cryptostegia grandiflora Roxb. ex R. Br., Parkinsonia aculeata L., Senna occidentalis (L.) Link, Datura ferox L. and Xanthium strumarium L. Except P. juliflora and P. hysterophorus, all others were not recorded in Ethiopia as IAS. P.juliflora was recorded in three plots with cover of 1% to 10%. P. juliflora was also found spread in different parts of the park particularly following the route of cattle movement. P. hysterophoruswas recorded in and around nine sample plots. Plot 46, 47 and 48 werehighly infested by P. hysterophorus which covered more than 60, 70 and 80% of the ground layer respectively. C. grandiflora was recorded in 11 plots with cover ranging from 1% to 35%. In view of all the natural as well as anthropogenic threats to the biodiversity of the Park, the ANP is at high risk. The rich biodiversity needsimmediate management intervention.

To prioritize weed management activities it is necessary to predict the extent of future infestations of individual weed species. Management effort should focus on populations which are likely to spread and produce new satellite populations. Deciding which aspects of an invading population to manage, new emerging distant satellites or the existing core from which most seed originates has been the subject of much debate. We use extensive survey data to define the core and satellite populations and dispersal function of Parkinsonia aculeata in the semi-arid rangelands of the Northern Territory of Australia. We described populations in terms of three size classes, classified on the basis of plant height (small ( 0.4 and 2.5 m)). Data were recorded as a spatial point pattern and a dispersal function was derived from the distribution of the distance of each medium plant to the nearest P. aculeata neighbour that was greater than 2.5 m. All large and medium P. aculeata were classified as members of core or satellite populations. From these classifications, we tested critical assumptions of Moody and Mack's model, namely (i) the satellites form multiple disjunct foci that do not overlap; (ii) the system is homogenous and there are no abiotic or biotic restrictions to the weeds expansion enabling it to expand radially in any direction; (iii) the densities of all foci are uniform; (iv) there is no extinction through stochastic processes; and (v) there are no threshold effects. When the medium size class was considered, the population density and area occupied by the weed increased. Two satellite populations were comprised solely of medium plants, suggesting the number of satellites increased marginally from eight to 10 when data from both size classes were considered. Most individuals were part of the core population. The core population increased in density and we argue this core population is most likely to give rise to new satellites and should be managed in preference to emerging satellite populations. We suggest the invasion is behaving like a source-sink system, where the core population is the source of most new medium plants.

The rangeland shrub, Parkinsonia aculeata (parkinsonia), is considered to be a serious pastoral and environmental weed in Australia. Existing biological control agents have been ineffective and native- range surveying is currently being undertaken to find potential new agents. In this paper I develop unambiguous performance criteria to assist in prioritising potential biological control agents, and against which the success of our biological control program can be judged. These include a reduction of patch density (to below 30% cover) and size (

The North American mirid Rhinacloa callicrates Herring was studied for suitability as an agent for the biological control of the woody weed Parkinsonia aculeata L. in Australia. It was tested for host specificity against 77 plant species, as well as for predatory behaviour against two beneficial insects and eggs of two Helicoverpa spp. Rhinacloa callicratesfed and oviposited almost exclusively on P. aculeata and did not prey upon the beneficial insects nor the Helicoverpa eggs. Rhinacloa callicrates was thus considered safe, and was released across northern Australia. Rhinacloa callicrates established in Queensland but has not controlled P. aculeata.

Parkinsonia aculeata L. (Leguminosae: Caesalpiniaceae), a weed in northern Australia, was the target of a biological control programme from 1983–1987. Sixty-five phytophagous insect species were collected fromP. aculeata growing in the Sonoran desert region of the southwestern United States and Mexico. Six orders (Coleoptera, Diptera, Hemiptera, Lepidoptera, Orthoptera and Thysanoptera) and 30 families were represented. Of the 12 species with potential as biological control agents, only one has passed specificity testing and has been released in Australia.

The bruchid beetle Stator vachelliae Bottimer will sometimes oviposit on seeds of the nonhost Parkinsonia aculeata (Leguminosae = Fabaceae), but most larvae do not survive. Of 1,118 eggs on Parkinsonia seeds, 86% occurred in a narrow zone where seeds of Parkinsonia and the normal leguminous host Acacia flexuosa were mixed on the ground beneath overlapping canopies. A field experiment indicated that females use nonseed cues associated with Acacia (pod valves and cow and horse dung) to locate Acacia seeds, and when seeds of both hosts are encountered, females oviposit equally on seeds of both plants. Other factors that were not controlled in the experiments (amount of daylight, temperature, humidity) may also affect discrimination between seeds of different hosts. Survivorship on Parkinsonia was

Parkinsonia aculeata L. is a shrubby tree which has generally been considered North American, but according to Hawkins et al. (2007), South America is included in the origi nal native range, with records in Argentina, Venezuela, Paraguay, and Brazil. In Brazil, it has a disjunct distribution, being found in northeast ("caatinga") and in south ("campos") (Lorenzi 2002). Similar disjunct distributions has been recorded for many other plants by Prado (2000), who explained the pattern based on climatic shifts in South America during the late Pleistocene. Thus, P. aculeata is clearly na tive to both the northeast and south regions of Brazil. Parkinsonia aculeata is useful for ornamenta

Morphometric, cytogenetic, geographical and ecological evidence for hybridization between Parkinsonia aculeata and Cercidium praecox is presented. Morphometric investigation using the character count procedure and cytogenetic observations confirm hybrid status. All diagnostic morphometric characters were intermediate in the hybrid. Both parents (2n = 28) show regular tetrad formation and pollen fertility greater than 94%. Hybrids have a chromosome number of 2n=28 or 2n=30, and display meiotic abnormalities including lagging chromosomes and micronucleus formation; less than 21% of hybrid pollen was fertile. Ecological and geographical information suggests that hybridization is occurring at increasing frequency due to the expanding range of P. aculeata associated with cultivation as an ornamental, coupled with ecological disturbance and weediness, and the cultivation of C. praecox and hybrids as fodder, ornamental and shade trees. Hybrid fertility and phenological observations, in conjunction with F-weighted principal component analysis, suggest that the progeny of F1 hybrids are established. The hybrid is formally described as P. x carterae.

An investigation of randomly amplified polymorphic DNA (RAPD) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) marker distribution was made for two well-characterised hybrids and their parents, Leucaena leucocephala and L. esculenta and Parkinsonia aculeata and Cercidium praecox. Three chloroplast DNA (cpDNA) markers identified the maternal parent of each L. leucocephala x L. esculenta hybrid. Fifteen species-diagnostic RAPD markers (invariant in one taxon and absent from the other) were always present in the Leucaena hybrid and assumed to be of nuclear origin, whilst three RAPD markers showed expression patterns identical to the cpDNA markers and were assumed to be of organellar origin. No RAPD or PCR-RFLP taxon-diagnostic markers were discovered for either P. aculeata or C. praecox. However, 21 RAPD markers were species-specific (polymorphic within one taxon but absent from the other) and Southern analysis indicated that none of the markers were of organellar origin. Only 67% additivity of markers specific to P. aculeata and C. praecox was demonstrated in the hybrids between these two species, whilst in Leucaena 97% additivity was demonstrated. Differences between the two hybridising situations were related to the behaviour of the molecular markers and the biology of the species.

Neolasioptera aculeatae Gagné (Diptera: Cecidomyiidae) is described as a new species from stem swellings on Parkinsonia aculeata L. (Leguminosae) in NW Argentina. The new species appears to be a good candidate for the biological control of its host in Australia, where the plant was accidentally introduced and is currently a serious pest. The species is shown to be distinct from its 64 Neotropical congeners. A preliminary key to these species is offered that can be adapted as more work is done on Neolasioptera.

Weeds of Australian rangelands have been the target for biological control since 1914. There have been several spectacular successes, e.g. prickly pear cactus (Opuntia spp.), with extraordinary ecological and commercial benefits. There have also been projects where no positive outcome has occurred, e.g. prickly acacia [Acacia nilotica (L.) Willd. ex Delile ssp. indica (Benth.) Brenan], parkinsonia (Parkinsonia aculeata L.), and creeping lantana [Lantana montevidensis (Spreng.) Briq.]. Numerous other projects are currently underway and require continuing support to achieve the stated aims. There is considerable potential to increase investment in biological control of rangeland weeds to improve outcomes of current projects and to implement new projects. There is promise of excellent benefits to cost ratios based on past performance. However, there is a worrying trend of loss of capacity in Australia to conduct biological control. Since resources will always be limited, it is important that the weeds that have the greatest impact on ecosystem function and commercial production are identified and targeted for management. Biological control should be part of the management strategies for those priority weeds when conflict over weediness v. commercial value can be resolved in favour of biological control, and when it is considered that biological control could offer benefits.

Age-class frequency distributions are valuable means of describing plant populations because they can be used to infer population history. Variables other than age are also often used to describe plant populations, either because they more accurately reflect an attribute of interest, or because it is difficult to determine age. However, interpretation of frequency distributions based on variables other than age can be problematic. We discuss these problems and illustrate them using data from six populations of the invasive rangeland shrub Parkinsonia aculeata L. We used three different measures of plant size: height, canopy diameter and stem cross-sectional area. Structures based on these measures were compared with structures based on three different estimates of above-ground biomass derived from them. For each variable, structures differed greatly between populations, and for each population, they were strongly dependent on the variable used to describe it. Population structures based on three-dimensional variables (above-ground biomass) tend to be more strongly positively skewed than those based on two-dimensional (area) measures of plant size. These in turn are more strongly positively skewed than those based on one-dimensional (height, diameter) measures. The statistical basis of this general phenomenon is discussed. The results highlight the difficulties of deriving histories and projecting futures of populations from size-class frequency distributions without accompanying knowledge of the temporal patterns of change in size variables as plants grow.

Parkinsonia aculeata is an invasive, introduced shrub that is found in all mainland states of Australia except Victoria. It is especially prevalent north of the tropic of Capricorn. Size-biomass relationships were established for this species using data from 167 shrubs spread across eight sites in the Northern Territory and north-eastern Queensland. Above-ground dry weight (W, kg) can be predicted from plant height (H, m), canopy diameter (D, m) or stem cross-sectional area (A, cm2) using the equations: W = 0.025 H4.47 W = 0.091 D3.64 W = 0.022 A1.61 These relationships are linear when plotted on log-log scales. Although there was a significant effect of "site" on the log-log relationships between above-ground dry weight and size variables, the amount of information lost by not using site-specific equations is relatively small. These results provide reliable methods for estimating above-ground biomass in this species, the most robust being based on measurements of stem diameter at 20 cm above ground level.

Stator chihuahua, S. limbatus, S. pruininus, S. pygidialis, S. sordidus , and S. vachelliae are all continuously breeding, noneconomic species. To determine reasons for their host preferences, these species were cultured in the laboratory, then presented with nonhost seeds, most of which were hosts for other species of Stator used in the study. S. limbatus, S. pruininus , and S. sordidus oviposited on a wide range of hosts, but S. vachelliae was very selective in the quality of seeds that it oviposited upon, and it completed development in only two nonhosts. S. limbatus, S. pruininus and S. sordidus completed their development in 3, 9, and 20 nonhost seeds, respectively. S. sordidus , which has only three natural hosts, is unique in being able to survive in so many non host seeds. The seed coats of Cercidium floridum, Parkinsonia aculeata , and some other plants are formidable barriers to the entry of Stator spp. Possible reasons for host preferences in Stator are given.

Callosobruchus maculatus bruchids (southern cowpea weevils) oviposited on the seed coats of 63 species of nonhosts in the laboratory. The first—instar larvae were unable to penetrate the seed coats of 17%, made a shallow pit in 30%, made a deep pit in 13%, and passed through the seed coats of the remaining 41%. Even when the seeds were cut in half, so that the eggs were laid directly on seed contents, the larvae died very shortly after mining into the seed contents of 92% of the 63 species. In only 1 case (Rhynchosia calycosa) did the bruchid develop normally and emerge from an intact seed. In 3 cases (Delonix regia, Parkinsonia aculeata and Schizolobium parahybum), the bruchid developed to a full—sized larva or an adult in the embryo of the seed but was unable to emerge by itself. In 9 species, the ♀ beetles refused to ovipost on the seeds, apparently because they were too small or because they were tomentose. It appeared that larvae failed to penetrate seed coats both because of their hardness and their toxicity. This demonstration that seed coats can be a barrier to a bruchid complicates the interpretation of the toxicity of seed contents and emphasizes the need to analyze seed contents separately from seed coats.

Field modifications of U.V. floral patterns of Caesalpinia eriostachys Benth. and Parkinsonia aculeata L. showed that bees used U.V. designs as orientation cues. Bees exhibited an in-flight orientation ability which was apparently correlated with size, with smaller bees frequently orienting to the manipulated position of the U.V. absorbent banner petal prior to landing on the flower. The U.V. absorptive banner petal and staminal portions of the flowers of both species seemed to be the most important visual orientation guides, and except for Trigona fuscipennis and T. pectoralis , the banner petal was the more important of the two. Emasculation of the flowers may have removed the orientation cue used by these species of Trigona , which may be orienting to the flowers solely on the basis of pollen odour. Morphological and physiological changes in the floral colour patterns of both species following pollination appear to inhibit visitation by bees. The significance of U.V. floral patterns was also considered.