Cercidium Floridum Research Articles

Buzzing towards Resilience: Investigating the Spatial Alignment of the Desert Pallid Bee, Centris pallida, and Its Host Plants in Response to Climate Change.

Wild bees are vital for the pollination of native plants and crops, providing essential ecosystem services. Climate change is known to impact biodiversity and species distributions, but insects adapted to desert ecosystems may exhibit unique physiological, behavioral, and evolutionary responses. The desert pallid bee (C. pallida), a solitary bee native to the arid southwestern United States and northern Mexico, primarily forages on yellow palo verde (P. microphylla), blue palo verde (P. florida), and desert ironwood (O. tesota). This study used MaxEnt to estimate the current and projected geographical overlap of suitable habitats for C. pallida and its host plants. Here, we used MaxEnt to estimate the current and forecasted overlapping geographically suitable habitat of C. pallida with all three host plants. We forecasted potential environmentally suitable areas for each species to the year 2040 using the current distribution model and climate projections with moderate CO2 levels. We found a continued spatial alignment in the suitable area of the bee and its host plants with a 70% increase in the range overlap area, though shifted to higher average altitudes and a slight northern expansion. These findings may provide insight to stakeholders on the conservation needs of desert-dwelling pollinators.

Composición bioquímica y mineral de especies vegetales consumidas por cabras en pastoreo en tres temporadas del año

Objetive. Determine and compare the biochemical and mineral composition of plant species consumed by grazing goats in three seasons of the year (drought, rain, and transition). Materials and methods. Sampling of the plant species that consume goats in each season of the year were made, during the time the goats feed on the rangeland, following them by the feeding paths and registering the species, the organs consumed, and the proportion of consumption This data were used to calculate a preference index, registering the frequency of consumption The three most consumed species by goats per season were selected. Results. The most consumed species in the drought season were Cyrtocarpa edulis, Pithecollobium confine, and Cercidium floridum. During the rainy season, the most consumed species were Forchhammeria watsonii, Tecoma stans, and Cercidium floridum. The most consumed species during rainy season were, Cyrtocarpa edulis, Indigofera suffruticosa, and Mimosa distachya. The protein content and ethereal extract were superior (p≤0.05) in the drought season. The content of Ca, Mg, Mn, K, P, and total-N were superior (p≤0.05) in the rainy season. Conclusions. The plant species associated with the rangeland in the study area, showed variation per season of the year in mineral and biochemical content, although are a source of minerals and nutrients for goats.

The benefits of woody plant stem photosynthesis extend to hydraulic function and drought survival in Parkinsonia florida.

As climate change exacerbates drought stress in many parts of the world, understanding plant physiological mechanisms for drought survival is critical to predicting ecosystem responses. Stem net photosynthesis, which is common in arid environments, may be a drought survival trait, but whether the additional carbon fixed by stems contributes to plant hydraulic function and drought survival in arid land plants is untested. We conducted a stem light-exclusion experiment on saplings of a widespread North American desert tree species, Parkinsonia florida L., and after shading acclimation, we then subjected half of the plants to a drought treatment to test the interaction between light exclusion and water limitation on growth, leaf and stem photosynthetic gas exchange, xylem embolism assessed with micro-computed tomography and gravimetric techniques, and survival. Growth, stem photosynthetic gas exchange, hydraulic function and survival all showed expected reductions in response to light exclusion. However, stem photosynthesis mitigated the drought-induced reductions in gas exchange, xylem embolism (percent loss of conductivity, PLC) and mortality. The highest mortality was in the combined light exclusion and drought treatment, and was related to stem PLC and native sapwood-specific hydraulic conductivity. This research highlights the integration of carbon economy and water transport. Our results show that additional carbon income by photosynthetic stems has an important role in the growth and survival of a widespread desert tree species during drought. This shift in function under conditions of increasing stress underscores the importance of considering stem photosynthesis for predicting drought-induced mortality not only for the additional supply of carbon, but also for its extended benefits for hydraulic function.

Germination and growth of the Sonoran Desert native trees under different agricultural conditions

Objective: To evaluate the germination, survival, and growth of Sonoran Desert native trees, in a fertile agricultural soil, with irrigation and protection against herbivory. Design/Methodology/Approach: For six months, the germination, survival, and growth of five tree species (Parkinsonia microphylla, Olneya tesota, Prosopis velutina, Guaiacum coulteri, and Parkinsonia florida) were evaluated in agricultural soil, with and without drip irrigation, avoiding herbivory. Results: The irrigated species O. tesota and P. velutina had the highest germination percentage (χ2 = 398.941, p < 0.0001). Plant survival was above 62 % (χ2 = 21.196, p < 0.0035), except for G. coulteri and P. florida without irrigation, which did not survive. At six months, P. florida recorded the greatest height (p < 0.0001), while all the species without irrigation and G. coulteri with irrigation recorded the lowest heights. Likewise, P. velutina, P. florida, and O. tesota (p < 0.0001) registered the greatest canopy cover at six months, while non-irrigated plants of all species and irrigated G. coulteri had the least cover. Limitations/Implications: Further agronomic studies are necessary to enable the successful establishment of commercial forest plantations, increasing knowledge about environmental problems. Findings/Conclusions: The five species of native plants studied can be established by direct sowing, in agricultural soil and with drip irrigation.

TagSeq for gene expression in non-model plants: A pilot study at the Santa Rita Experimental Range NEON core site.

PremiseTagSeq is a cost‐effective approach for gene expression studies requiring a large number of samples. To date, TagSeq studies in plants have been limited to those with a high‐quality reference genome. We tested the suitability of reference transcriptomes for TagSeq in non‐model plants, as part of a study of natural gene expression variation at the Santa Rita Experimental Range National Ecological Observatory Network (NEON) core site.MethodsTissue for TagSeq was sampled from multiple individuals of four species (Bouteloua aristidoides and Eragrostis lehmanniana [Poaceae], Tidestromia lanuginosa [Amaranthaceae], and Parkinsonia florida [Fabaceae]) at two locations on three dates (56 samples total). One sample per species was used to create a reference transcriptome via standard RNA‐seq. TagSeq performance was assessed by recovery of reference loci, specificity of tag alignments, and variation among samples.ResultsA high fraction of tags aligned to each reference and mapped uniquely. Expression patterns were quantifiable for tens of thousands of loci, which revealed consistent spatial differentiation in expression for all species.DiscussionTagSeq using de novo reference transcriptomes was an effective approach to quantifying gene expression in this study. Tags were highly locus specific and generated biologically informative profiles for four non‐model plant species.

Response of four species of Sonoran Desert trees to buffel grass removal treatments

Buffel grass (Cenchrus ciliaris L.) is an African grass used as forage for livestock that is also invasive. Several methods have been evaluated to remove invasive buffel grass, but the effect of removal on establishment of native plants is poorly understood. We explore the effect of buffel grass removal treatments on the germination and establishment of four Sonoran Desert tree species. We used three removal treatments and a control; after treatments were applied, we sowed seeds of Mariosousa willardiana, Parkinsonia microphylla, Olneya tesota, and Parkinsonia florida. For each treatment, we evaluated germination, plant survival and measured soil moisture, soil temperature, and light quantity. In a second experiment, we tested whether glyphosate, an herbicide used in removal treatments, had significant effects on the same native species. Additionally, in a third experiment, we evaluated the effect of glyphosate on a native annual species. Results showed that the herbicide treatment was effective killing buffel grass and promoting the regeneration of native species. Germination and survival rates for the four study species were greatest under the herbicide treatment and lower after manual removal treatments of buffel grass. However, the herbicide glyphosate significantly suppressed the survival and growth of seedlings of the studied tree species and the annual species. Given the effect of glyphosate on native seedlings and other known side effects, we suggest that it is used only to target buffel plants, avoiding contact with native vegetation.

Characterization of Ti Ringspot-Associated Virus, a Novel Emaravirus Associated with an Emerging Ringspot Disease of Cordyline fruticosa.

Ti ringspot is an emerging foliar disease of the ti plant (Cordyline fruticosa) in Hawaii that is quickly spreading throughout the islands. Symptoms include small chlorotic ringspots on leaves that often coalesce to form larger lesions. Although several virus species have been discovered in symptomatic plants, none have been associated with these symptoms. Here, we report and characterize a novel virus closely associated with ti ringspot symptoms in Hawaii. The presence of double membrane bodies approximately 85 nm in diameter in symptomatic cells and sequence analyses of five genomic RNA segments obtained by high-throughput sequencing indicate that this virus is most closely related to members of the plant virus genus Emaravirus. Phylogenetic and sequence homology analyses place this virus on a distinct clade within the Emaravirus genus along with High Plains wheat mosaic emaravirus, blue palo verde broom virus, and Raspberry leaf blotch emaravirus. Sequence identity values with taxonomically relevant proteins indicate that this represents a new virus species, which we are tentatively naming ti ringspot-associated virus (TiRSaV). TiRSaV-specific reverse transcription PCR assays detected the virus in several experimental herbaceous host species following mechanical inoculation. TiRSaV was also detected in eriophyid mites collected from symptomatic ti plants, which may represent a putative arthropod vector of the virus.

Biosynthesis of gold and silver nanoparticles using Parkinsonia florida leaf extract and antimicrobial activity of silver nanoparticles

In this work, the biosynthesis of gold and silver nanoparticles from a leaf extract of Parkinsonia florida (P. florida) is reported. The P. florida leaf extract was analyzed by a phytochemical screening, by measuring the DPPH radical scavenging activity, and by Fourier-transform infrared spectroscopy (FT-IR). The phytochemical screening results indicated that biomolecules like carbohydrates, phenols, proteins, aminoacids, saponins, and flavonoids present in P. florida leaf extract might have participated in the chemical reduction of the metallic salts and further colloidal stabilization. The FT-IR results from leaf extract functional groups support the role of surface modification with the presence of residues of phenols, proteins, aminoacids, saponins, and flavonoids. The formation of metallic nanoparticles was confirmed by optical absorption spectroscopy with characteristic absorption bands at 550 nm and 430 nm, for gold and silver nanoparticles, respectively. Zeta potential for gold nanoparticles presents negative values in the range of −10 ± 1 to −16 ± 1 mV, depending on the amount of leaf extract used during the synthesis reaction. Similarly, zeta potential values for silver nanoparticles were in the range of −5 ± 1 to −16 ± 1 mV. STEM images revealed the average particles sizes in the range from 10 to 15 nm, and 10 to 57 nm, for gold and silver nanoparticles respectively. The silver nanoparticles presented good antibacterial activity, inhibiting the growth of Staphylococcus aureus and Escherichia coli.

Remotely Sensed Spatial Structure as an Indicator of Internal Changes of Vegetation Communities in Desert Landscapes

Desert environments are sensitive to disturbances, and their functions and processes can take many years to recover. Detecting early signs of disturbance is critical, but developing such a capability for expansive remote desert regions is challenging. Using a variogram and 15-cm resolution Visible Atmospherically Resistant Index (VARI) imagery, we examined the usefulness of the spatial structure of desert lands for monitoring early signs of habitat changes using the Riverside East solar energy zone located within Riverside County, California. We tested the method on four habitat types in the region, Parkinsonia florida–Olneya tesota, Chorizanthe rigida–Geraea canescens, Larrea tridentata–Ambrosia dumosa, and Larrea tridentata–Encelia farinosa alliances. The results showed that the sill, range, form, and partial sill of the variogram generated from VARI strongly correlate with overall vegetation cover, average canopy size, canopy size variation, and spatial structure within a dryland habitat, respectively. Establishing a baseline of variogram parameters for each habitat and comparing to subsequent monitoring parameters would be most effective for detecting internal changes because values of variogram parameters would not match absolute values of landscape properties. When monitoring habitats across varying landscape characteristics, a single appropriate image resolution would likely be the resolution that could adequately characterize the habitat dominated by the smallest vegetation. For the variogram generated from VARI, which correlates to vegetation greenness, the sills may indicate the health of vegetation communities. However, further studies are warranted to determine the effectiveness of variograms for monitoring habitat health. Remotely sensed landscape structure obtained from variograms could provide complementary information to traditional methods for monitoring internal changes in dryland vegetation communities.

Restoration of eroded soil in the Sonoran Desert with native leguminous trees using plant growth-promoting microorganisms and limited amounts of compost and water

Restoration of highly eroded desert land was attempted in the southern Sonoran Desert that had lost its natural capacity for self-revegetation. In six field experiments, the fields were planted with three native leguminous trees: mesquite amargo Prosopis articulata, and yellow and blue palo verde Parkinsonia microphylla and Parkinsonia florida. Restoration included inoculation with two of plant growth-promoting bacteria (PGPB; Azospirillum brasilense and Bacillus pumilus), native arbuscular mycorrhizal (AM) fungi, and small quantities of compost. Irrigation was applied, when necessary, to reach a rainy year (300mm) of the area. The plots were maintained for 61 months. Survival of the trees was marginally affected by all supplements after 30 months, in the range of 60-90%. This variation depended on the plant species, where all young trees were established after 3 months. Plant density was a crucial variable and, in general, low plant density enhanced survival. High planting density was detrimental. Survival significantly declined in trees 61 months after planting. No general response of the trees to plant growth-promoting microorganisms and compost was found. Mesquite amargo and yellow palo verde responded well (height, number of branches, and diameter of the main stem) to inoculation with PGPB, AM fungi, and compost supplementation after three months of application. Fewer positive effects were recorded after 30 months. Blue palo verde did not respond to most treatments and had the lowest survival. Specific plant growth parameters were affected to varying degrees to inoculations or amendments, primarily depending on the tree species. Some combinations of tree/inoculant/amendment resulted in small negative effects or no response when measured after extended periods of time. Using native leguminous trees, this study demonstrated that restoration of severely eroded desert lands was possible.

Effects of seed beetles on the performance of desert legumes depend on host species, plant stage, and beetle density

Seeds of many arid habitat plants have a water-impermeable coat and can germinate only after being scarified. Bruchine seed beetles are important parasites of legume seeds in these environments, but their effect on germination can be unpredictable. Beetles deplete seed resources and can kill the embryo but also scarify seeds. We investigated the effects of a generalist parasite, Stator limbatus, on the germination and growth of two common legumes in the Sonoran desert, catclaw acacia (Acacia greggii) and blue paloverde (Parkinsonia florida). Feeding damage from a single larva greatly increased germination of paloverde but not acacia. This benefit was reduced if seeds were attacked by multiple larvae. Beetle-damaged seeds of both hosts germinated more quickly than did control seeds. Infestation by beetles reduced seedling size, though effects were greater for paloverde than for acacia. Our results demonstrate that the effect of S. limbatus can be highly host-specific. In addition, beetle infestation may enhance or reduce seedling recruitment, depending on the availability of other scarifying agents and the number of larvae per seed. Such contingencies make it difficult to predict the net effect of seed beetles on efforts to control invasive legume hosts or establish native hosts during aridland restoration.

Localization and Speciation of Arsenic in Soil and Desert Plant Parkinsonia florida Using μXRF and μXANES

Parkinsonia florida is a plant species native to the semidesert regions of North America. The cultivation characteristics of this shrub/tree suggest that it could be used for phytoremediation purposes in semiarid regions. This work describes, through the use of synchrotron μXRF and μXANES techniques and ICP-OES, the arsenic (As) accumulation and distribution in P. florida plants grown in two soils spiked with As at 20 mg kg(-1). Plants grown in a sandy soil accumulated at least twice more As in the roots compared to plants grown in a loamy soil. The lower As accumulation in plants grown in the loamy soil corresponded to a lower concentration of As in the water-soluble fraction (WSF) of this soil. LC-ICP-MS speciation analysis showed only As(V) in the WSF from all treatments. In contrast, linear combination XANES speciation analysis from the root tissues showed As mainly present in the reduced As(III) form. Moreover, a fraction of the reduced As was found coordinating to S in a form consistent with As-Cys(3). The percentage of As coordinated to sulfur was smaller for plants grown in the loamy soil when compared to the sandy soil.

Toxicity and biotransformation of ZnO nanoparticles in the desert plants Prosopis juliflora-velutina, Salsola tragus and Parkinsonia florida

Although arid and semiarid regions account for about 40% of world land, no nanotoxicity studies on desert plants have been reported. In this investigation, Parkinsonia florida (blue palo verde), Prosopis juliflora-velutina (velvet mesquite) and Salsola tragus (tumbleweed) were selected to determine the phytotoxicity of ZnO nanoparticles (NPs) at germination stage. Seeds were treated with ZnO NP concentrations ranging between 0 and 4000 mg L−1. From this, the germination rate, root elongation and Zn concentration in tissues were determined. Furthermore, X-ray Absorption Spectroscopic (XAS) studies were performed to obtain preliminary information on potential NP biotransformation within plant tissues. Results indicated that germination was not significantly affected (P < 0.05) in any of the three plant species. Also, root elongation in blue palo verde was reduced by 16%, with respect to control at 4000 mg ZnO L−1. Tumbleweed root size diminished by 14% and 16% at ZnO NP levels of 500 and 2000 mg L−1, respectively, and velvet mesquite root length was reduced to all ZnO NP concentrations used in this study. The 50% inhibitory concentration (IC50) for mesquite root elongation was between 1000 mg L−1 and 2000 mg L−1. XAS results demonstrated that ZnO NPs were biotransformed on/within the root and Zn was present as Zn(II) in the three desert plant species.

Top-down, bottom-up, and horizontal mortality variation in a generalist seed beetle

The study of the interacting factors that constrain resource use in organisms and promote diversity is an important task, especially in a mega diverse area, in which the increasing transformation of ecosystems modifies the interactions among organisms. among the hypotheses that explain resource use and diversity of insects are the Top­ down and the Bottom­up hypotheses, in which experimental studies have shown trade­offs between these factors. The influence of parasitism, host plant and competition was evaluated to determine their effect on mortality of the seed beetle Stator limbatus from populations adapted to different host plants. Mortality of eggs caused by parasitism, and mortality of larvae caused by competition was recorded for seven populations that use a single host seed, and for one population that uses two hosts. Populations that use Acacia greggii experienced the lowest mortality, and populations that use Parkinsonia florida suffered the highest mortality, demonstrating no evidence of trade­offs between bottom­up and top­down factors. Interactions between host and larval density, and between host and number of eggs on seeds, showed variation between hosts in the mortality of beetles caused by competition and by parasitism, respectively. In addition, there was no evidence of egg size affecting parasitism of eggs. These results show the need of including in the traditional bottom­up and top­down explanations, the study of factors that could be mediating their outcome such as the one examined here (competition). This need is more urgent now that we are exposing ecosystems to accelerated changes in structure, functioning, and composition.

Responses of native legume desert trees used for reforestation in the Sonoran Desert to plant growth-promoting microorganisms in screen house

Three slow-growing legume trees used for desert reforestation and urban gardening in the Sonoran Desert of Northwestern Mexico and the Southwestern USA were evaluated whether their growth can be promoted by inoculation with plant growth-promoting bacteria (Azospirillum brasilense and Bacillus pumilus), unidentified arbuscular mycorrhizal (AM) fungi (mainly Glomus sp.), and supplementation with common compost under regular screenhouse cultivation common to these trees in nurseries. Mesquite amargo (Prosopis articulata) and yellow palo verde (Parkinsonia microphylla) had different positive responses to several of the parameters tested while blue palo verde (Parkinsonia florida) did not respond. Survival of all tree species was over 80% and survival of mesquite was almost 100% after 10 months of cultivation. Inoculation with growth-promoting microorganisms induced significant effects on the leaf gas exchange of these trees, measured as transpiration and diffusive resistance, when these trees were cultivated without water restrictions.

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.

Blue Palo Verde, Parkinsonia florida (Benth. ex Grey) S. Wats. (Fabaceae), a new host of the introduced carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae), in southern California

Blue Palo Verde, Parkinsonia florida (Benth. ex Grey) S. Wats. (Fabaceae), a new host of the introduced carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae), in southern California

Desert mistletoe ( Phoradendron californicum) infestation correlates with blue palo verde ( Cercidium floridum) mortality during a severe drought in the Mojave desert

Effects of plant parasitism on plant hosts are dependant upon cumulative biotic and abiotic environmental conditions. Blue palo verde ( Cercidium floridum, Leguminoceae) is parasitized by desert mistletoe ( Phoradendron californicum, Viscaceae) across its range. Mistletoe infestations are positively correlated with host tree height, and not with host mortality in the Sonoran Desert, but this system has not been monitored previously in the Mojave where water availability is less predictable. We mapped the distribution of 1212 live palo verdes in June of 2001 and 77 dead trees in January of 2002 and quantified parasite load on an 80 ha site in California. Blue palo verde mortality is highly positively correlated with mistletoe infestation, host height, and interaction of host size and plant parasite load in this study. 96.7% of trees without mistletoe were alive at the conclusion of the study, compared to only 38.6% of trees with mistletoe infestations. An SPI drought index of the area shows that droughts occur in an episodic manner, potentially causing periodic large-scale palo verde mortality during periods of severe drought. Results highlight the necessity to monitor plant host–parasite interactions across their range as interactions are apt to change with varying environmental conditions.

Selection on body size and sexual size dimorphism differs between host species in a seed-feeding beetle

Sexual size dimorphism varies substantially among populations and species but we have little understanding of the sources of selection generating this variation. We used path analysis to study how oviposition host affects selection on body size in a seed-feeding beetle (Stator limbatus) in which males contribute large ejaculates (nuptial gifts) to females. Females use nutrients in these ejaculates for egg production. Male body size, which affects ejaculate size, affects female fecundity and is thus under fecundity selection similar in magnitude to the fecundity selection on female body size. We show that when eggs are laid on a host on which larval mortality is low (seeds of Acacia greggii) fecundity predicts fitness very well and fecundity selection is the major source of selection on both male and female adult size. In contrast, when eggs are laid on a host on which larval mortality is high (seeds of Parkinsonia florida) fecundity poorly predicts fitness such that fecundity selection is relaxed on both male and female size. However, because egg size affects larval mortality on this poor host (P. florida) there is selection on female size via the female size --> egg size --> fitness path; this selection via egg size offsets the reduction in fecundity selection on female, but not male, body size. Thus, differences in host suitability (due to differences in larval mortality) affect the relative importance of two sources of selection on adult body size; fecundity selection on both male and female body size is lower on the poor quality host (P. florida) relative to the high quality host (A. greggii) whereas selection on female body size via effects of egg size on offspring survival (body size --> egg size --> fitness) is greater on the poor quality host relative to the high quality host. Because selection via the egg size path affects only females the difference in larval survival between hosts shifts the relative magnitude of selection on female vs. male size. Researchers working on other study systems should be alerted to the possible importance of subtle, but consequential, indirect selection on their study organisms.

Watering blue palo verde ( Cercidium floridum) affects berry maturation of parasitic desert mistletoe ( Phoradendron californicum) during an extreme drought in the Mojave Desert

Resources available to parasites are often dependent on resources available to hosts. If a resource is limiting to parasites because it is limiting to hosts, supplementing that resource for hosts should affect parasites. Water availability is a limiting factor for plant productivity in many desert systems. We watered blue palo verde ( Cercidium floridum) with desert mistletoe ( Phoradendron californicum) infestations during a drought in the Mojave Desert during winter of 2002–2003. Mistletoe berries were monitored over a 19-week period on nine trees receiving no water, nine trees receiving “normal” water, and nine trees receiving 10× normal water. No differences were seen in overall berry numbers between treatments. However, berry crops on mistletoe plants parasitizing watered palo verdes matured and numbers declined faster than berry crops on control trees. There were no differences between plants watered a moderate amount and those watered a magnitude more, suggesting that berry maturation may be limited by a factor other than water in wet years, or that palo verde do not uptake significantly more water than is typically present. Future research is needed to conclusively determine factors limiting desert mistletoe berry maturation.