Species Of Columnar Cacti Research Articles

Enhanced mycorrhization in four species of columnar cacti under the Sonoran Desert tree <em>Olneya tesota</em>

Background: Columnar cacti survival in deserts occurs mainly under nurse plants, due to better conditions for germination and establishment, as greater humidity, and nutrient concentration. However, interactions like the association between arbuscular mycorrhizal fungi (AMF) and roots remain relatively unexplored. We evaluated the mycorrhizal status and soil rhizosphere properties of four columnar cacti species growing both under and outside their nurse plant. Hypotheses: Soil properties improvement under nurse plants has been correlated with the abundance of AMF. Therefore, a greater number of AMF structures and roots mycorrhization would be in facilitated plants, compared to the same species growing outside the nurse. Studied species: Nurse plant: Olneya tesota, facilitated species: Carnegiea gigantea, Pachycereus pringlei, Pachycereus schottii, and Stenocereus thurberi. Study site and dates: Central Gulf Coast subdivision of the Sonoran Desert, Sonora, Mexico; October 2020. Methods: Cacti roots and soil rhizosphere were collected under and outside the nurse plant. Roots were stained, and mycorrhizal colonization (MC), hairy roots (HR), visual density (VD), and number of spores were determined. Physicochemical soil properties were analyzed. Results: Values of MC, VD, spore number, organic matter (OM), nitrate, and total and assimilable phosphorous were higher under the nurse compared to bare areas. Conclusions: The hypothesis that mycorrhization parameters are greater in roots of cacti growing under the nurse was confirmed, besides previous knowledge about soil quality under nurse plants, suggesting that AMF play a significant role in the cacti facilitation process under nurses plants, and that nurse plant plays a significant role in AMF formation.

Pollen morphology of columnar cacti from Tehuacán-Cuicatlán Valley, Mexico

The most important centre of diversity and endemism of columnar cacti in Mexico is the Tehuacán-Cuicatlán Valley (Puebla-Oaxaca states). The aims of this paper are (1) to provide a detailed description of the recent pollen morphology of 19 registered species that are found in this valley and (2) to develop a synoptic table to differentiate groups of species. This synoptic table is based on morphological features of pollen grains and the density of structural and sculptural elements observed using light and scanning electron microscopy. All analysed pollen grains were stenopalynous: isopolar monads, large, tricolpate with perforate tectate exine (sexine-nexine ratio 1:1), columellate structure with pattern of columellae distribution and spinulose sculpture. The spinules were always wider than they were tall. Although the 19 species of columnar cacti analysed in this study show highly similar types of pollen grains, we were able to characterise each of them with combined microscopy techniques.

Environmental gradualism explains variation in pollination systems of columnar cacti: Phylogenetic and trait evolution analyses

AbstractAimThe geographical dichotomy hypothesis (GDH) states several flowering plant groups have specialized pollination systems in tropical areas where resources are more reliable and pollinator communities tend to be more stable, than in extratropical areas. Our main goal was to understand the scope of the GDH and/or gradual environmental variation considering the evolutionary history of the pollination traits.LocationNeotropical tropics and adjacent extratropics.Major taxa studiedColumnar cacti.MethodsUsing a database composed of ~54 columnar cacti species (31.7% of the global columnar cactus species), four complex traits were analysed: pollination syndromes, reproductive systems, type of anthesis, and duration of anthesis. We conducted generalized linear models (GLMs), phylogenetic regressions, evolutionary trait optimization, and multivariate models with 19 bioclimatic variables and potential evapotranspiration.ResultsWeak phylogenetic signal was detected for all traits, giving consistent results between GLMs and phylogenetic regression analysis. The pollination syndrome and duration of anthesis varied with latitude, in contrast to the reproductive system and the type of anthesis. In the Southern Hemisphere, the pollinators were more diverse and the duration of anthesis was longer. Different evolutionary paths between hemispheres were detected and optimization showed a complex pattern in the evolution of traits, suggesting high homoplasy with multiple transformations by convergence and/or parallelism. The environmental models showed thermic seasonality may be at the core of the latitudinal variation of the pollination system.Main conclusionsWe did not detect a geographical dichotomy in pollination systems of the cacti, but rather a gradual change in different pollination attributes. Therefore, instead of a GDH, we propose an environmental gradient hypothesis (EGH). Environmental variables may be explaining the variation detected in pollination system traits by conditioning floral properties (morphology, phenology), diversity and distribution of pollinators, and/or coevolution occurrence. The complexity implied in these traits is consistent with high homoplasy levels and a differential evolutionary history between the hemispheres.

Trichocereus atacamensis (Phil.) W.T.Marshall & T.M.Bock (Cactaceae) shows decreasing germination fractions with seed age and differences in regeneration niche compared with a congeneric, sympatric species (T. tarijensis (Vaupel) Werderm.)

The Cactaceae are a characteristic component of arid zones in the American continent. Some species are known to possess a seed bank, as a way to cope with environmental uncertainty, albeit seeds usually lose viability with time. Seed banks may respond with a constant, low germination proportion (delayed germination) or germination may depend on rainfall amount (predictive germination). On the other hand, several species of cacti usually co-occur in one locality. In the case of large, columnar species, we would expect competition as a corollary of their history of coexistence. We conducted two irrigation experiments (three watering levels: 40, 60, 80mm) to assess how seed viability in one columnar cactus is lost as years pass (three years), and to determine differences in germination/ early survival between two dominant columnar, sympatric cacti (Trichocereus atacamensis (Phil.) W.T.Marshall & T.M.Bock, T. tarijensis (Vaupel) Werderm.) from the arid puna. We predicted seeds from more recent years would have greater germination fractions and survival, and that the two columnar cactus species would show differences in their regeneration niche in order to decrease competition. We found a tendency for greater germination in younger seeds, and no effect of seed age on survival. Seeds from one of the species (T. atacamensis) had twice as many survivors as the other species (T. tarijensis). Both species showed a predictive response to water, having greater germination proportions with more irrigation. In conclusion, seed age affected germination, the columnar cactus species had a predictive germination, and showed differences in some aspects of their regeneration niche.

Chemical profiling of Trichocereus species from northern Argentina

The first nutritional profiling of all Trichocereus species of columnar cacti from northern Argentina is reported. Commonly called ‘cardones’ by locals, they are iconic elements of the flora and cultural heritage in the region. A general chemical characterization of the four species (T. atacamensis, T. terschekii, T. tarijensis and T.schikendatzii) was performed. Stem tissues for each species in terms of humidity, ash, protein content, carbohydrates, and reducing sugars, as well as phenols and anti-radical activity were profiled. The results constitute an advance in terms of general knowledge of these vulnerable and exploited Andean cacti and will contribute to ponder the most appropriate method of conservation and the possibility of bioprospecting and regulating its sustainable use.

What are the demographic consequences of a seed bank stage for columnar cacti?

AbstractThe dynamics of plant populations are often limited by the early stages in their life cycles. However, information regarding seed bank dynamics and how these may influence the whole life cycle of plant species is remarkably scarce or not considered explicitly. This lack of knowledge is due mainly to the challenges in quantifying seed vital rates. Studies of arid land plant species have historically been focused on the drivers of sporadic recruitment. However, little attention has been given to the demographic consequences of early developmental stages, and how seed banks affect their dynamics. Here, we evaluate the effects of seed bank survival and seedling recruitment vital rates on the population dynamics and viability of 12 columnar cacti species. Recent evidence suggests that cacti seeds may remain viable for the short‐term. We assess how changes in the vital rates of these processes and the inclusion of a seed bank affect population growth rate (λ). We found that a seed bank in the examined matrix population models significantly increased λ as well as the vital rate elasticities of λ to growth and fecundity, whereas that of overall survival decreased. Our numerical simulations showed that seed survival had a more considerable effect on λ than seedling recruitment and establishment. We suggest that the seed bank may explain the structure and population dynamics. Thus, we reconsider that this early stage in demographic models will generate more informed decisions on the conservation and management of columnar cacti.

A protocol for health assessment of cacti populations: A case study from Northwestern Argentina

Argentina is considered megadiverse for Cactaceae, and Jujuy province, with a high proportion of cacti endemism, is a critical region for their preservation. Cacti deterioration is mainly associated with habitat degradation, agricultural frontier advance, urbanization, illegal collection and trade. Of the three species of columnar cacti within Trichocereus genus that are present, Trichocereus atacamensis represents a valuable species for local communities. In the last decades, detrimental effects on T. atacamensis populations increased despite the reduction in the use of timber for construction or handicrafts. Knowledge on the health of cacti populations is fundamental for conservation and resource management, therefore the objective of the present study was to develop a health status classification criterion for cacti in Quebrada de Humahuaca, Jujuy. A generic method was elaborated to assess the health of cacti populations to facilitate and speed-up the decision-making process for conservation purposes. The evaluation of factors involved in the deterioration is very complex. We designed a method considering aspects that the local residents identified as the most relevant: a) presence of air plant (genus Tillandsia), b) larvae of Cactoblastis bucyrus and c) signs of rot. Band transects were sampled in patches of T. atacamensis, surveying these aspects for each individual. A Multivariate Regression Tree analysis (MRT) was conducted. According to this clustering, an accessible assessment protocol with a 5-level health status was established to classify the cactus as optimal, suboptimal, compromised, vulnerable or critical. The general health status of the patches was highly variable. This MRT analysis is potentially applicable to any columnar cacti population and to establish the basis of a decision protocol for health status assessment. It is evident that the situation of T. atacamensis transcends as a local problem and exceeds the presence of pathogens suggesting a multifactorial causality that needs special attention.

Periderm coverages on five species of long-lived columnar cactus species of central Mexico

Sunlight exposures have resulted in periderm coverages on more than 40 species of tall, long-lived columnar cactus species in the Americas. Periderm coverages start on equatorial surfaces and eventually cover all surfaces. Periderm coverages lead to tissue morbidity and eventual cactus death. After more than 80% of periderm coverage on saguaro (Carnegiea gigantea) cacti, the probability of cactus death was greater than 95% within eight years. Periderm coverage characteristics were not similar for five species of tall, long-lived columnar cactus species endemic to the Tehuacán-Cuicatlán Valley (18° N), Puebla, Mexico. For four species, trough coverages were higher for south-facing surfaces than north-facing surfaces. For these four species periderm ratios were near 2:1, S:N. This 2:1 ratio is coincident with the ratio of direct sunlight exposures on S: N surfaces. For one species, the amounts of periderm were low so no differences in periderm coverages occur of south to north were present. Unlike cacti at other locations, crests of species of this study did not show a directional effect. The results indicate that periderm formation occurred first on south-facing surface and eventually occurred on other surfaces. Results with Random Forest, an algorithm, reinforce results of periderm percentages. Random forest was used to determine surfaces coverages that predict periderm coverages on other surfaces. As expected, neighboring surfaces were the best predictors of periderm coverages. Other surfaces were not good predictors of periderm coverages indicating that other surfaces had periderm coverage before or after the predicted surfaces. Random Forest data were the same for all five species. Although, the patterns of the five species showed some variability, they all support that hypothesis that periderm coverages start on south-facing surfaces and eventually occur on north-facing surfaces and they are caused by sunlight.

Establishing population boundaries and conservation proposals for Coleocephalocereus purpureus, a critically endangered cactus species microendemic from Caatinga biome

Coleocephalocereus purpureus (Buining & Brederoo) F. Ritter is a rare columnar cactus species endemic to four small habitat patches of a south-eastern caatinga inselberg elements located in Eastern Brazil. C. purpureus was listed as Critically Endangered by IUCN by habitat loss due to quarrying activities. Here, we used ten microsatellite markers to estimate genetic diversity and structure of C. purpureus populational groups to perform a remaining genetic diversity diagnosis and to define population boundaries. Our estimates of genetic diversity indicated that C. purpureus displayed moderated levels of genetic diversity, even though the species populational groups are small and fragmented. All genetic structuring approaches revealed that there is a clear differentiation in two populations isolated by the Jequitinhonha River, named here as South and North populations. The South population corresponds to a unique group placed in a disturbed non-protected area and the North population comprises three groups, including the admixtured and managed group placed in a Conservation Unit. As priority actions for the retention of genetic diversity of C. purpureus populations, we propose (i) that the isolated population should be considered as a prior for conservation efforts and managed as an independent unit; (ii) maintaining the integrity of the habitat within the four small patches that constitute the range of the species; (iii) continuous monitoring of genetic diversity of the populational groups; (iii) improve the quality of local pollinator habitats in order to avoid the inbreeding; and (iv) ex-situ conservation actions should be considered, especially the transfer of C. purpureus representatives to botanical gardens as well formation of a seed bank.

Areole Changes During Bark Formation for Columnar Cactus Species

Bark coverage occurs on stems of more than twenty species of columnar cacti. This report documents characteristics of areoles and spines from central Mexico with bark coverage percentages on five columnar cactus species (Cephalocereus columna-trajani, Neobuxbaumia macrocephala, N. mezcalaensis, N. tetetzo, and Pachycereus hollianus). Older cacti (more than 4 m tall) had fewer original spines than younger cacti (less than 2 m tall). For cacti taller than 4 m, loss of the original spines was positively correlated with bark coverage. For three species, loss of the original spines occurred with about 75% for bark coverages. Four of the five species studied produced hair-like spines at areoles. Three of the five species produced emergent spines. Most emergent spines were associated with hair-like spines. The presence of hair-like and emergent spines (spines that emerged on mature cactus surfaces) was not well correlated with percentages of bark coverage. Hair-like spines have been noted previously, but no function has been attributed to them. This is the first report with a description of emergent spines on tall, long-lived columnar cactus species.

Traditional management of microorganisms in fermented beverages from cactus fruits in Mexico: an ethnobiological approach

BackgroundFermentation is an ancient technique for preserving and improving the qualities of food and beverages throughout the world. Microbial communities, not seen by the producers of fermented goods, are the actors involved in the fermentation process and are selected upon through different management processes in order to achieve a final product with culturally accepted features. This study documented the preparation of “colonche” which is a type of traditionally fermented beverages made with the fruits from several cactus species in two main producing regions of Mexico, the Altiplano and the Tehuacán Valley. We documented the selection processes of the cactus species used and the practices that could influence microbial community composition, as well as, how the producers reach the desirable sensorial attributes of the beverages.MethodsWe conducted 53 semi-structured interviews and participatory observations with colonche producers in 7 communities of the Altiplano and the Tehuacán Valley in order to characterize the practices and processes involved in the elaboration of the beverage. Opuntia and columnar cacti species used in colonche production were collected during fieldwork and identified. Selected sensorial attributes of Opuntia colonches were characterized by a ranking table and visualized by principal component analysis in order to distinguish differences of this beverage in the Altiplano localities.ResultsThirteen cactus species are used for colonche production in both regions studied. In the Altiplano, the most commonly used fruit is Opuntia streptacantha because it contributes to the preferred attributes of the beverage in this region. Selection of substrates by producers depends on their preference and the availability of fruits of O. streptacantha and other species. Fermentation is mainly conducted in clay pots which is perceived to be the best type of vessel contributing to the preferred sensorial properties of colonche. The two main differences in colonche preparation between the villages are the practice of boiling the fruit juice and the use of pulque (fermented sap of Agave species) as inoculum. The most contrasting sensorial attributes selected between localities are the alcohol content and sweetness, which might be in accordance with the practices used for obtaining the final product. Colonche is produced mainly for direct consumption and secondarily used as a commercialized good to be sold for economic gains contributing to the general subsistence of households. The preparation methods are passed on by close relatives, mainly women.ConclusionsTraditional producers of colonche use several techniques in order to reach specific sensorial attributes of the final product. The production of colonche has been upheld for generations but fermentation practices are divided into two categories; (1) the use of an inoculum (either from pulque, or from colonche saved from the previous year), and (2) the use of “spontaneous” fermentation. The differing practices documented reflect the contrasts in the preferred sensorial attributes between regions. Colonche is a beverage that contributes to regional pride, cultural identity and is appreciated because of its gastronomic value. Here, we argue that there is a clear relationship of human knowledge in the management of microbiota composition in order to produce this beverage. In-depth documentation of the microbiota composition and dynamics in colonche will contribute to the preservation of this valuable biocultural heritage.

Damage in Cactaceae, their geographic distribution and new evidences

Background: Field observations of damage in columnar cacti of central Mexico, and previous evidence in scientific literature, indicated the absence of systematic information about kinds of damage, vectors, and pathogens, in this botanical family.
 Questions: How is the knowledge of damage and defense mechanisms in cacti? Is there a pattern in causal agents and their geographical distribution in the Americas?
 Methods: A database of 58 taxa by 51 types of damage was developed from literature recorded in ISI Web of Knowledge, Cabdirect, and Google Scholar, and it was analyzed by multivariate methods.
 Results: From 1,500 species of Cactaceae, only 58 have been studied through this scope. Subfamily Cactoideae has been the most studied, in particular tribe Echinocereeae (= Pachycereeae columnar cacti). Multivariate analysis grouped cacti according to the kind of damage: biotic, or abiotic. Damage due to biotic factors was sub-grouped depending on the herbivores. Damage by abiotic factors is more frequent in extreme latitudes. Fourteen species of columnar cacti were reported with herbivory and rot damage in Central Mexico, of which eight represent new records of damaged cacti. 
 Conclusions: The evidence from field observations, and few recent publications suggest that some generalist herbivores are becoming dangerous in this region, Future research is necessary in order to understand the dynamics of the dispersion of some kinds of damage, the role of human disturbance, and the role and changes in defense mechanisms in wild and domesticated cacti.

Natural History Notes for the Columnar, Globular and Semi-Epiphytic Cactus Species of the Island of Puerto Rico

Abstract: The island of Puerto Rico is home to five species of columnar, globular and semi-epiphytic cacti: Pilosocereus royenii, Melocactus intortus, Stenocereus fimbriatus, Leptocereus quadricostatus and Hylocereus trigonus. However, their ecology and natural history are still largely unknown. We visited a total of 12 sites during four years. We identified habitat preferences for each cactus species; recorded the incidence of fires and the invasion of grasses in these habitats. We also recorded bird-cactus interactions during 150 hrs. of observation. Observations on the reproduction biology of S. fimbriatus is provided for the first time, and differences of M. intortus morphology of two populations were assessed. Finally, we identify different threats to the Puerto Rican native cacti and dry forests. We also identified various questions on the basic ecology and biology of these cactus species that should be addressed in future works.

Areole Changes during Bark Formation on Saguaro Cacti

Spines are an important component of cactus species. Besides providing protection from predation, they reduce heat loading, reduce transpiration, and aid dispersal of stem segments for vegetative propagation among others. Bark formation occurs on surfaces of more than twenty species of columnar cacti in the Americas. For all species tested, bark formation is related to direct sunlight exposure. Extensive bark coverage leads to premature death for saguaro cacti (Carnegiea gigantea). Preliminary evidence indicates that changes in areoles with spines occurred during the bark formation on C. gigantea. Four hundred, sixty-one paired photographic images of areoles of north- and south-facing surfaces of shoots with bark percentages on adjacent troughs in 2017 were analyzed to determine differences between north- and south-facing surfaces. As in past studies, south-facing surfaces had higher bark percentages (mean bark coverage 62%) than north-facing surfaces (mean bark coverage 19%). For north and south areoles, mean numbers of central spines were 2.70/1.55; radial spines 3.20/1.50; and apex spines 1.81/1.13, respectively. When data were pooled to compare numbers of central, radial and apex spines as well as spine color and spine thickness, all were significantly related with bark percentages. Decreases in numbers and characteristics of spines precede bark formation on adjacent troughs. Overall, the results show that crests deteriorate faster than adjacent troughs. To our knowledge, this is the first report to document changes in spine numbers and characteristics with bark coverage on a cactus species.

Reproductive biology of Oreocereus fossulatus (Cactaceae), a long‐lived columnar cactus endemic to the tropical Andes

AbstractThe geographic dichotomy hypothesis suggests that columnar cacti inhabiting the tropics depend on flower visitors (birds and bats) for their pollination, showing highly specialized animal‐pollinated systems. This pattern has been demonstrated for the northern hemisphere; however, our knowledge of the species of columnar cacti growing in the southern tropics is still scarce. In this study, we studied the reproductive biology of Oreocereus fossulatus (Cactaceae, Tribe Trichocereae), an endemic, columnar cactus of the tropical Andes, to determine if its pollination system tends to be more generalized (mixed systems of autogamy and xenogamy) than specialized (xenogamy) as a consequence of the geographic position of where it lives. Observations of the frequency of visits showed that Patagona gigas (Trochillidae) is its main pollinator. It visits the flowers when they are open, coinciding with the periods of greater floral reward (dusk and dawn of the first day of anthesis). The treatments of autogamy, xenogamy and geitonogamy produced fruits, showing that O. fossulatus exhibits a generalized pollination system, in the same way as its congeneric species O. celsianus, which is distributed farther south in the Prepuna biogeographical region. Our results suggest that species partially specializing in pollination by hummingbirds and, besides, capable of autopollination, could be common in the tropical and subtropical Andes, probably as a response to the unpredictable environments present in their ecosystems.

Prickly problems of cacti phylogeny

Cactus Genomics![Figure][1] The genomes and relationships of columnar cacti, such as the saguaro, have been resolved. PHOTO: JAYPIERSTORFF/SHUTTERSTOCK The evolutionary history of cacti has been difficult to resolve. Copetti et al. sequenced the genomes of four species of columnar cacti,

Rates of bark formation on surfaces of saguaro cacti (Carnegiea gigantea)1, 2

Abstract Twenty-one species of tall, long-lived columnar cactus species show extensive bark coverage (epidermal browning) in the Americas. Each species shows more bark coverage on equatorial-facing surfaces than on polar-facing surfaces. In addition, controlled experiments with supplemental UV-B irradiation show the initial stages of bark coverage. These two facts suggest that UV-B irradiation is the cause of sunlight-induced bark coverage. This sunlight-induced bark leads to premature morbidity and mortality. Saguaro cactus (Carnegiea gigantea (Engelm.) Britton & Rose) of southern Arizona is the most researched cactus species with regard to this bark coverage. The current effort focused on bark coverage rates on 12 cactus surfaces at 1.7 m height above ground by comparing logistic curves of relative bark coverage among stem surfaces. Logistic curves have been used to document progress of many diseases in humans. In this study, logistic curves were best fit to data with least squares analysis in all cases...

Attractiveness of Different Food Resources to Dung Beetles (Coleoptera: Scarabaeidae) of a Dry Tropical Area.

Excrement scarcity is one of the main historical factors leading dung beetles to adapt to other food resources. In the Caatinga, a seasonally tropical dry forest, harsh environmental conditions seem to restrict the availability of food resources. In this scenario, the aim of our study was to experimentally investigate the attractiveness of different potential food resources to these insects in the Caatinga. Field samplings were performed, and we tested five resources in pitfall baited traps: excrement, carrion, fruits of two species of columnar cacti, and seeds of one species of Euphorbiaceae (Jatropha mollissima (Pohl)). In a controlled setting, we tested dietary preferences of Deltochilum verruciferum Felsche by offering one or two resources simultaneously. In the field experiments, 297 dung beetles (9 species) were recovered from the traps, and D. verruciferum was the most abundant species. Carrion and excrement were the most attractive resources. Controlled dietary preference tests with D. verruciferum evidenced that these beetles used all tested food resources, excrement and carrion most pronouncedly. Our findings support copro-necrophagy as the main feeding habit of D. verruciferum, but also suggest that alternative resources might be utilized if preferred resources are scarce.

Phylogenetic analyses ofPilosocereus(Cactaceae) inferred from plastid and nuclear sequences

Pilosocereus is a large genus of Cactaceae with 42 species of columnar cacti distributed in the Americas. In this work we investigate the phylogenetics and evolutionary history of Pilosocereus based in plastid and nuclear DNA sequences. We use phylogenetic trees obtained as a basis to analyse infrageneric relationships and to study the evolution of selected morphological characters and geographical distribution in the group. Thirty-three species of the genus were sampled and five molecular regions were selected, four non-coding intergenic spacers of plastid DNA (trnS-trnG, psbD-trnT, trnL-trnT, petL-psbE) and one nuclear low-copy gene (phytochrome C). The phylogenetic analyses obtained point to a paraphyletic Pilosocereus, with P. bohlei and P. gounellei emerging nested in a clade of outgroup species (i.e. other genera of Cereinae). However, the majority of species of the genus form one well supported clade (excluding P. bohlei and P. gounellei) corresponding mostly to Pilosocereus subgenus Pilosocereus. Evidence indicates that the ancestor of Pilosocereus subgenus Pilosocereus clade was a shrub with a straight floral tube occurring in Brazil and the ancestor of Pilosocereus subgenus Gounellea was a shrub with a curved floral tube also occurring in Brazil. The ancestral distribution in central and eastern Brazil resulted in the diversification of most lineages in the same area, whereas the P. leucocephalus clade was able to disperse through the Amazonian areas and diversify further north and reach Central and North America.

Flowering Phenology and Observations on the Pollination Biology of South American Cacti. 2.Cereus aethiops

Abstract: Observations of plant-pollinator interactions are an important component of the study of the overall ecological setting of a plant species. Here, we report two species of sphingids as pollinators of Cereus aethiops, a wide-spread shrubby columnar cactus species from the Argentinian Monte vegetation. Cereus aethiops is remarkable for its desiccation tolerance during the dry winter season and rapid rehydration after the first rainfall during the summer season. Rehydration starts within 24 hours after the start of the first significant rain, and is complete within 7 to 10 days. Flower bud initiation is triggered by the first rainfall event, and the time from the first rain to the start of the flowering season shows little year-to-year variation. The flowers conform to the sphingophilous pollination syndrome, and the expected sphingid pollinators could be confirmed by direct observation. Diurnal plant-insect interactions in C. aethiops are insignificant and most likely do not contribute significantl...