Gustavia Superba Research Articles

Host Specificity and Wood Density-Based Host Choice by Longhorn Beetles (Coleoptera: Cerambycidae) in a Panamanian Lowland Rainforest

We evaluated the larval host plant specificity of Cerambycidae in a tropical lowland rainforest in Panama.Beetleswere reared from standardized timber baits of freshly-cut wood exposed for 35 days to ovipositing females in the Galeta Island Protected Area, Colon province, Panama. Baits from six species of woody plants belonging to five families yielded 109 longhorn beetles, representing 11 species in nine genera.Host specificity was low,with themajority of longhorn species reared fromwood of more than one plant family. Only the genus Inga Mill. (Fabaceae) hosted a possibly specialized species (Cosmotoma fasciata Fisher). Longhorn abundance and diversity were highest in Gustavia superba (Kunth) O. Berg (Lecythidaceae). Most adults emerged four and six months after the timber baits were exposed. Fifty-seven percent of longhorn beetles were reared from low wood density trees (400–460 kg/m3); we do not have enough data to propose reliable wood density preferences for other cerambycids reared in this study. More rearing samples will be required to support the results shown in this paper.

Study of the carotenoid composition in membrillo, guanabana toreta, jobo and mamey fruits

Introduction. Many tropical fruits have great health potential due to the possible presence of bioactive phytochemicals. Natural food composition databases are very important sources of information relative to natural food biodiversity and nutritional properties. The objective of this study was to report for the first time on the native carotenoid composition of the fruit of four tropical species from Panama. Materials and methods. Fully mature fruit were collected in Panama and analyzed by HPLC-DAD-APCI-MS, after carotenoid extraction with acetone. Results and discussion. The carotenoid composition had never been previously reported for two of the investigated fruits, membrillo (Gustavia superba ) and guanabana toreta (Annona purpurea ). In membrillo, 5 different carotenoids were detected; the content of total carotenoids was 318.6 μ g g-1 fresh weight (fw), with β -carotene showing a relative abundance of 75.3%. In guanabana toreta, 11 different carotenoids were detected; the total carotenoid content was 48.3 μ g g-1 fw, with β -carotene and zeaxanthin showing a relative abundance of 26.9% and 27.5%, respectively. In jobo (Spondias mombin ), 11 different carotenoids were detected; the total carotenoid content was 45.8 μ g g-1 fw, with β -cryptoxanthin, α -carotene and β -carotene showing a relative abundance of 25.4%, 10.5% and 8.5%, respectively. In mamey (Mammea americana ), 16 different carotenoids were detected; the total carotenoid content was 145.2 μ g g-1 fw; in particular, 10 different violaxanthin fatty acid diesters, of both cis and trans isomers, were determined. Conclusion. The consumption of the fruit studied should be promoted both locally and abroad, because of the reported presence of these health-promoting phytochemicals.

The effect of light, seed size and biomass removal on cotyledon reserve use and root mass allocation inGustavia superbaseedlings

Abstract:Some large-seeded tree species have cotyledonary reserves that persist for months after seedling establishment. We carried out two screened growing-house experiments with seedlings ofGustavia superba(Lecythidaceae) to test hypotheses proposed to explain why cotyledons are retained. We grew seedlings from large and small seeds in sun and shade to determine if cotyledon reserves supplement photosynthetic carbon gain, and in a second experiment applied defoliation and shoot removal treatments to determine if reserves are allocated to resprout tissue. In each experiment we tracked cotyledonary resource use over time and measured the fraction of seedling biomass allocated to roots and shoots. We found no evidence that light environment, seed size or damage treatment affected the rate of cotyledon resource usage; 20% of the cotyledonary mass remained 9 wk after leaves were fully developed in both sun and shade and 25–30% of the cotyledonary mass remained 6 wk after leaf or shoot removal. Instead, cotyledon reserves appear to be slowly translocated to roots regardless of light environment or seedling damage. Once seedlings are established, lost tissue is replaced using reserves stored in roots; in high light, damaged seedlings had a lower root mass fraction (0.42) than undamaged ones (0.56) when considering the mass of tissue removed and resprout tissue combined. We conclude that cotyledon reserves are important for resprouting during early seedling emergence and establishment, but do not directly contribute to seedling growth or biomass recovery from herbivores at the post-establishment stage. Persistence of cotyledons may ultimately depend on the development of sufficient root mass for reserve reallocation.

Trenching increased growth, and irrigation increased survival of tree seedlings in the understorey of a semi-evergreen rain forest in Panama

Seedlings in tropical forests are ultimately the source of canopy trees, thus factors controlling their composition and growth potentially influence the composition of the forest. Seedlings are primarily limited by above-ground competition with trees, but below-ground competition is potentially also important. Over 4 y we experimentally reduced below-ground competition by trenching to 50 cm and reduced drought stress by irrigating in the dry seasons (6 cm every 2 d) in the understorey of a semi-evergreen rain forest in Panama. There were four irrigated plots and four unirrigated, in each plot there were eight subplots (four trenched, four untrenched); 32 seedlings (two per subplot) of each of four tree species were equally allocated to the four treaments; the four species were: Aspidosperma cruenta; Gustavia superba; Simarouba amara and Tachigali versicolor. Over all species together, trenching increased seedling height by 41% and leaf area by 140% over 4 y. The cause was likely to be increased nutrient supply, because the amounts of N, K and Ca were higher in trenched plants, though concentrations were not higher. Irrigation had no significant effect on growth. Irrigation, but not trenching, reduced seedling mortality. We conclude that below-ground competition was a major limitation for seedling growth for at least some common species (Gustavia and Tachigali in this experiment). More experiments are necessary to determine whether below-ground competition is also important in other tropical rain forests on fairly fertile soils.

GAPS AND ROOT TRENCHING INCREASE TREE SEEDLING GROWTH IN PANAMANIAN SEMI-EVERGREEN FOREST

Although competition between plants is nearly universal in vegetation, we know relatively little about belowground competition and how it interacts with aboveground competition in tropical forests, and almost nothing about such interactions on soils of intermediate fertility in sites with a moderate dry season, despite the fact that such forests are extensive. We investigated this over one year in a Panamanian tropical semi-evergreen rain forest, using tree seedlings (Simarouba amara, Gustavia superba, Tachigali versicolor, and Aspidosperma cruenta; least to most shade tolerant), experimental gaps, and trenching. Gaps increased growth and decreased mortality; growth increases were: Simarouba 684% (increase in height relative growth rate), Gustavia 411%, Aspidosperma 364%, and Tachigali 324%. Trenching in gaps increased growth in three species (Simarouba 49%, Gustavia 63%, and Aspidosperma 38%) but had very small effects in the understory; trenching did not affect mortality. We infer that trenching caused increased growth due to increased nutrients in the wet season, and increased water and/or nutrients in the dry season. Thus, across the tropics, in all but the wettest sites with fertile soils, seedlings of many species will be limited by belowground competition, at least in gaps. This is similar to the pervasive importance of belowground competition in temperate forests.

Influence of a common palm, Oenocarpus mapora, on seedling establishment in a tropical moist forest in Panama

Plants often modify microsite conditions important for seedling establishment. In tropical moist forest, advance regeneration in the form of shade-suppressed seedlings is a major component of regrowth in new gaps. Tree seedlings may be filtered by the composition and structure of the forest understorey. In a lowland forest in Central Panama, we examined light availability, litter accumulation and the seedling community (abundance, diversity and composition) under and away from the canopies of a common subcanopy, clonal palm, Oenocarpus mapora, and tested whether seedling abundance varies as a function of changes in understorey light conditions and leaf litter depth. We found evidence that leaf litter was five times deeper and light availability 27% lower under O. mapora canopy than where it was absent. The probability of finding a seedling in plots under O. mapora canopies was 33% lower than in plots without the palm. Plots under O. mapora canopies also had 49% fewer species of seedlings and those seedlings came from significantly larger seeds than seedlings in plots not under the palm. Overall, seedling density was positively correlated with light availability and negatively correlated with leaf litter depth. A transplant experiment confirmed that for at least one large-seeded species of dicot, seedlings are negatively affected by the reduction in light availability and increase in leaf litter. Under O. mapora, seedlings of Gustavia superba (Lecythidaceae) had lower survivorship and biomass accumulation than away from the palm. Thus, site conditions produced by large, clonal, multi-layered palms such as O. mapora may reduce establishment of small-seeded and shade-intolerant species, potentially affecting species composition in the understorey seedling pool.

Multiple resprouting from diaspores and single cotyledons in the Australian tropical tree species Idiospermum australiense

In 1999, Dalling & Harms simulated 100% above-ground herbivory on seedlings of Gustavia superba, a large-seeded species from Barro Colorado Island, Panama, and showed the remarkable ability for cotyledons to regenerate up to eight new shoots. They used this evidence to propose that cotyledon size (at least in this species)was adaptive in surviving pre- and early post-germination hazards (Dalling & Harms 1999). In this note we describe the first record of multiple resprouting in an Australian tropical plant species. Idiospermum australiense (Diels) S. T. Blake (Calycanthaceae) exhibits characteristics similar (but not identical) to G. superba that support the contention of Dalling & Harms (1999).

Flood tolerance of four tropical tree species.

Many seasonally flooded habitats in the tropics are dominated by one or a few tree species. We tested the hypothesis that the inability to tolerate flooding restricts most species from becoming established in flood-prone habitats. We compared morphological and physiological responses to flooding in seedlings of Prioria copaifera Griseb., a species that forms monodominant stands in seasonally flooded habitats, and in three species confined to flood-free sites; namely, Calophyllum longifolium Willd., Virola surinamensis Aubl. and Gustavia superba (H.B.K.) Berg. Flooding reduced photosynthesis at Day 45 in all species by 10-30%. By Day 90, photosynthesis returned to the control rate in Prioria, but not in the other species. Flooding reduced stomatal conductance by 25-35% in all species except Calophyllum, and it reduced leaf area growth by 44% in Virola, but not in the other species. All species survived 90 days of flooding without mortality, leaf chlorosis, leaf necrosis, or leaf abscission. Flooding reduced root:shoot ratio significantly in Gustavia and Calophyllum, but not in the other species, and it reduced maximum root depth by 29% in Prioria, but by 61% or more in the species from flood-free habitats.

Damage Tolerance and Cotyledonary Resource Use in the Tropical tree Gustavia superba

Explanations for the extremely large seed size of some tropical forest plants are currently lacking. In this study we examine cotyledonary resource use of the tropical tree Gustavia superba, and test whether tolerance to damage of either seeds or establishing seedlings might be an important function leading to, or maintaining, its large ( > 5 g) seed reserves. We found that seeds of Gustavia were both tolerant of insect infestation and were also capable of successful germination after removal of half of their cotyledonary reserves. Simulated complete above-ground herbivory resulted in repeated resprouting (up to 8 times). Resprout shoots were constructed of a small, but fixed proportion of remaining cotyledonary mass regardless of seed size. In the absence of damage, cotyledon reserves were used for onward seedling growth: however, conversion of cotyledon resources was slow, lasting several months. Given high rates of damage to Gustavia seeds and seedlings in the field, and the apparent use of cotyledonary reserves to tolerate or recover from it in growing house experiments, we conclude that cotyledonary seed size and morphology in this species is adaptive in surviving pre- and early post-germination hazards.

Growth dynamics of root and shoot hydraulic conductance in seedlings of five neotropical tree species: scaling to show possible adaptation to differing light regimes.

The dynamics of growth (shoot and root dry weights, surface areas, hydraulic conductances, and root length) were measured in seedlings of five neotropical tree species aged 4-16 months. The species studied included two light-demanding pioneers (Miconia argentea and Apeiba membranacea) and three shade-tolerant young- or old-forest species (Pouteria reticulata, Gustavia superba, and Trichilia tuberculata). Growth analysis revealed that shoot and root dry weights and hydraulic conductances and leaf area all increased exponentially with time. Alternative methods of scaling measured parameters to reveal differences that might explain adaptations to microsites are discussed. Scaling root conductance to root surface area or root length revealed a few species differences but nothing that correlated with adaptation to light regimes. Scaling of root surface area or root length to root dry weight revealed that pioneers produced significantly more root area and length per gram dry weight investment than shade-tolerant species. Scaling of root and shoot hydraulic conductances to leaf area and scaling of root conductance to root dry weight and shoot conductance to shoot dry weight also revealed that pioneers were significantly more conductive to water than shade-tolerant species. The advantages of scaling hydraulic parameters to leaf surface area are discussed in terms of the Ohm's law analogue of water flow in plants.

Does Mammal Community Composition Control Recruitment in Neotropical Forests? Evidence from Panama

Patterns of seed predation, germination, and seedling herbivory were investigated in Panamanian forests. We hypothesized that seed and seedling survival would vary with differences in mammal community composition. We tested this hypothesis at five sites in mainland forests adjacent to Gatun Lake, full terrestrial mammalian granivore/herbivore communities with top predators; at five sites on Barro Colorado Island (BCI), also a full mammalian granivore/herbivore community but without the two largest cats; at one site each on five medium-sized islands, with rats, agouti, rabbit, and paca present; and on five small islands that support rats only. Experiments were replicated for Dipteryx panamensis, Gustavia superba, and Virola nobilis, all of which have large seeds. To assess seed removal, seeds were placed in wire exclosure cages and nearby outside the cages. There was no difference in removal rates between forest types, with almost all unprotected seeds removed at all sites. To assess post-removal seed fate, seeds of Gustavia and Virola were attached to threads and placed on the forest floor. All threaded seeds were victims of predation on small islands, whereas 34, 43, and 77% of threaded seeds were dispersed and buried on BCI, medium islands, and the mainland, respectively. To assess seedling herbivory, half of the wire exclosure cages were removed after germination, and seedling survival was assessed after 13–14 mo. Protection from mammals increased seedling survivorship by more than sixfold on the smallest islands, by threefold on the medium islands, by twofold on the mainland, and by less than twofold on BCI. The absence of the two largest cats and the exclusion of poachers from BCI was associated with lower seedling herbivory and higher seed predation than observed on the mainland. In contrast, extreme mammal defaunation on the small and medium islands had large and consistent effects on seedling recruitment, including increased seed predation and increased seedling herbivory relative to sites with more intact mammal communities.

DOES MAMMAL COMMUNITY COMPOSITION CONTROL RECRUITMENT IN NEOTROPICAL FORESTS? EVIDENCE FROM PANAMA

Patterns of seed predation, germination, and seedling herbivory were investigated in Panamanian forests. We hypothesized that seed and seedling survival would vary with differences in mammal community composition. We tested this hypothesis at five sites in mainland forests adjacent to Gatun Lake, full terrestrial mammalian granivore/herbivore communities with top predators; at five sites on Barro Colorado Island (BCI), also a full mammalian granivore/herbivore community but without the two largest cats; at one site each on five medium-sized islands, with rats, agouti, rabbit, and paca present; and on five small islands that support rats only. Experiments were replicated for Dipteryx panamensis, Gustavia superba, and Virola nobilis, all of which have large seeds. To assess seed removal, seeds were placed in wire exclosure cages and nearby outside the cages. There was no difference in removal rates between forest types, with almost all unprotected seeds removed at all sites. To assess post-removal seed fate, seeds of Gustavia and Virola were attached to threads and placed on the forest floor. All threaded seeds were victims of predation on small islands, whereas 34, 43, and 77% of threaded seeds were dispersed and buried on BCI, medium islands, and the mainland, respectively. To assess seedling herbivory, half of the wire exclosure cages were removed after germination, and seedling survival was assessed after 13–14 mo. Protection from mammals increased seedling survivorship by more than sixfold on the smallest islands, by threefold on the medium islands, by twofold on the mainland, and by less than twofold on BCI. The absence of the two largest cats and the exclusion of poachers from BCI was associated with lower seedling herbivory and higher seed predation than observed on the mainland. In contrast, extreme mammal defaunation on the small and medium islands had large and consistent effects on seedling recruitment, including increased seed predation and increased seedling herbivory relative to sites with more intact mammal communities.

Interspecific Variation in Rates of Trunk Wound Closure in a Panamanian Lowland Forest

We evaluated the ability to close wounds inflicted with a drill to the trunks of seven common tree species from Barro Colorado Nature Monument, Panama. We predicted that species lacking wood antimicrobial activity would rapidly close wounds to prevent pathogen entrance, while those species with wood antimicrobial defenses need not necessarily exhibit fast wound closure. The species studied were Alseis blackiana, Gustavia superba, Miconia argentea, Poulsenia armata, Protium panamense, P. tenuifolium, and Tetragastris panamensis. Callus, resins, and latex were all involved in wound closure, but mechanisms varied among species: after 3 months, the only pioneer species, Miconia, had minimal diameter closure; Alseis showed intermediate closure only by callus; and the other five species (which did not differ) had almost completely plugged their wounds by means of combined callus and resin production (Tetragastris and both species of Protium), latex (Poulsenia), or callus and woody flakes (Gustavia). Our initial prediction was supported for Gustavia and Poulsenia (i.e., rapid wound closure and no wood antimicrobial activity) but not for Tetragastris and Protium (that showed both rapid wound dosure and strong wood antimicrobial activity); Miconia showed slow wound dosure and no wood antimicrobial activity. Only for Alseis, was wound dosure rate proportional to stem diameter growth.

Seed Removal and Seed Fate in Gustavia superba (Lecythidaceae)

The fate of the large (mean 12.6 g) seeds of Gustavia superba, an understory tree, was analyzed on Barro Colorado Island (BCI), Panama. Eight hundred thread-marked seeds were placed on the ground at two contrasting 1-ha forest sites (Gustavia-rich vs Gustavia-poor) during two periods (June and July) of the fruiting season of G. superba. These months correspond to maximum food availability on BCI. On average, 85.5 percent of the seeds were removed within 28 days, 47.5 percent and 3.8 percent of them being found scatterhoarded (buried) by agouti (Dasyprocta punctata) and gnawed by rodents, respectively, within 10 m of their origins. The effect of site and the interaction of site with month significantly affected seed removal rates, but not scatterhoarding rates. Proportions of seeds removed were greater where G. superba trees were rare. Because freshly fallen seeds were not infested by bruchid weevils, unburied and germinating seeds provide an abundant short-term food supply for terrestrial mammals. Burying seeds allowed agoutis to later consume cotyledons of germinating seeds from mid-August throughout October, when food is scarce on BCI. Overall seed dispersal effectiveness (% seed dispersal multiplied by % seedling survival) contrasts dramatically between forest sites, being 10.1 percent and 0.75 percent at Gustavia-rich and Gustavia-poor areas, respectively. This result suggests that predator-disperser satiation occurred, maybe due to greater G. superba seed availability and other alternative food supply, allowing greater G. superba seedling survival at the Gustavia-rich area.

The Effect of Leaf Litter on Early Seedling Establishment in a Tropical Forest

The presence of leaf litter of different depths within a tropical forest creates many different microsites for plant establishment. The amount and distribution of leaf litter within a forest can influence patterns of plant establishment. In this study, we determined the spatial variability in leaf litter in the forest understory, and investigated how different litter depths (bare, 1, 6, and 12 cm) affected the establishment of several tropical tree species in both growth house (sun and shade) and field (gap and understory) experiments in the semideciduous tropical forest of Barro Colorado Island, Panama. The tree species used in this study (Aspidospermum cruenta, Ceiba pentandra, Cordia alliodora, Gustavia Superba, Luehea semmannii, Ochroma pyrimidale) were chosen to represent a range of seed masses and a gradient in the light requirement for establishment of the species. The spatial distribution of leaf litter was not correlated between adjacent sampling points within the forest understory, suggesting that the establishment environment for seedlings, with respect to litter, is highly variable at scales of 1—20 m. The presence of litter affected five of the six species, but the nature and the magnitude of the effect were species specific. The smaller seeded shade—intolerant species had fewer seedlings establishing under leaf litter than on bare ground. The species ranged from strongly nagatively affected (Luehae) to moderately negatively affected (Cordia, Ochroma) to affected only by extreme amounts of litter (Ceiba). The presence of litter influenced Gustavia, one of the larger seeded shade—tolerant species, but did not affect Aspidospermum, the other large seeded species. The effect of litter on Gustavia depended on the light environment. Gustavia had more seedlings establishing under litter in the sun, but the presence of litter had no effect in the shade. Differences among the smaller seeded shade—intolerant species in the amount they were negatively influenced by litter were not correlated with seed mass. Data from our field study were consistent with our growth house results for the shade—intolerant species. Additional data from the field study indicated that these species with similar habitat requirements differed in the developmental stage at which they were affected by the presence of litter. Luehea had fewer seeds germinating under litter while the other two species, Ochroma and Cordia, were affected only after germination. Interspecific comparisons done for each light level and litter depth indicated that the presence of litter caused reversals in the relative ranking of species success. For example, Gustavia preferentially established under relatively deep litter depths in the sun where Luehea could not establish. In conclusion, the presence of litter can potentially increase seedling diversity within the forest by creating heterogeneity in the establishment environment and by causing reversals in species' rankings.

Synchronous leaf production and herbivory in juveniles of Gustavia superba.

Synchronous leaf production has been proposed as a mechanism to reduce herbivore damage to young leaves by satiating herbivores. To test this hypothesis, I measured leaf production, leaf survivorship, and herbivore damage on juveniles of Gustavia superba (H.B.K.) Berg (Lecythidaceae), in two sites in Central Panama. Leaves were produced throughout the year, but there were peaks in leaf production at the beginning of the wet scason. Plants that produced leaves synchronously with conspecifics received significantly less damage than plants that produced leaves out of synchrony, and high levels of leaf damage were correlated with shorter leaf lifetimes. These data suggest that plant phenology can influence risks of herbivory.

The Effects of Rapid Leaf Expansion on the Growth and Suvivorship of a Lepidopteran Herbivore

Gustavia superba, a common understory tropical tree in the young forest of Barro Colorado Island, Panami, produces leaves synchronously and has very rapid leaf expansion. Rapid leaf expansion followed by a decrease in leaf contribute to larval mortality of a major herbivore, Entheus priassus. Most larval mortality occurs during the first and second instars and appears to be directly related to leaf age at the time of hatching. Larvae that hatch on expanding leaves have a higher probability of surviving than larvae that hatch on fully expanded leaves. Because of the rapid leaf expansion, ovipositing E. priassus females have only a few days to locate suitable host leaves. We believe that rapid leaf expansion in G. superba acts as a defense by minimizing the time the leaf is acceptable for oviposition due to the rapid decline in leaf quality after the completion of leaf expansion. A possible cost of rapid leaf expansion is high levels of nitrogen in the young leaves, which may make these leaves more palatable to a greater range of herbivores.

Effects of Predation and Light on Seedling Establishment in Gustavia Superba

Large—seeded trees whose seeds are dispersed by mammals often have high levels of seed dispersal but high seed losses due to predation. Consequently, seedling establishment is influenced both by the impact of mammalian seed predators as well as by the ability of the seedling to survive where the seed is dispersed. I examined the relative roles of seed/seedling predation by mammals and of the light environment in seedling establishment in three populations of the tropical tree Gustavia superba. One population was located in semideciduous forest on Gigante Peninsula and two were on Barro Colorado Island (BCI), Panama. On Gigante Peninsula, mammals that feed on Gustavia fruit and seeds were much less abundant than on BCI. My objectives were: (1) to quantify seedling densities in each population, (2) to measure the intensity of seed predation, and (3) to determine the relative importance of seed/seedling predation and light in seedling survival and growth. Seedling density was significantly greater on the Gigante Peninsula than on BCI. This pattern was influenced by postdispersal seed predation that was much lower on the Gigante Peninsula than on BCI. Seedling transplant experiments, which measured the effects of site, light condition (gap, edge, understory), and protection from mammals (tall cage, short cage, no cage), showed that protection from mammals significantly increased all three measures of seedling performance: seedling survival, seedling height, and overall seedling success (survival times growth). In addition, as expected from differences in mammal abundance among sites, the three sites differed in the extent to which each measure of seedling performance was affected by seedling protection. Seedling survival, growth, and overall success were significantly greater on the Gigante Peninsula than on BCI. However, even on the Gigante Peninsula, seedlings benefitted significantly by protection from mammals. All three measures of seedling performance were greater in light gaps than in the understory, but seedlings survived well in the understory at all three sites. I conclude that seedling density was determined primarily by mammalian predation on both seeds and seedlings, although seedling establishment was influenced also by site and light conditions. Large seeds size, which probably increases vulnerability to mammalian see predators, facilitates the establishment of seedlings under low light conditions.

Notes on the Floral Biology of Couroupita guianensis Aubl. (Lecythidaceae)

Floral biology has been studied in relatively few Lecythidaceae, despite their ecological importance in the Neotropics. Only a few authors have dealt with the subject, notably Jackson and Salas (1965) on Lecythis ellipitica H.B.K., Dias (1967) on Bertholletia excelsa Humb. & Bonpl., Mori and Kallunki (1976) on Gustavia superba (Kunth) Berg., Prance (1983) on Eschweilera garagarae Pittier, and Prance (1976) and Mori et al. (1978) on pollination and androecial structure in the family as a whole. Ormond et al. (1981) published a contribution to the floral biology of Couroupita guianensis after all of our field observations were completed and a draft of this paper was submitted for publication. Prance (1976) and Mori et al. (1978) pointed out that the androecial zygomorphy and the position of the hood (adpressed to the ring) in Couroupita subsessilis Pilg. suggest that the genus Couroupita may be intermediate in the family with respect to androecial evolution. Few studies of anthesis behavior in tropical plants, including Lecythidaceae, have been carried out. Notably, Mori et al. (.1978) reported diurnal anthesis and shedding of stamens during the late afternoon for Lecythis amara Aublet (= L. alba Mori, nom. nud.), and asynchronous anthesis during the morning for Eschweilera longipes (Poit.) Miers.; the latter of which sheds its androecia the following day. Differentiaf behavior between pollen produced in ring anthers and that found in hood anthers is documented by Mori and Orchard (1979), Mori et al. (1980a), and Ormond et al. (1981). Floral visits by potential pollinators, such as wasps and small bees, have been reported by Prance (1976), Mori et al. (1978), and Ormond et al. (1981).

Germination Response in a Large-Seeded Neotropical Tree Species, Gustavia superba (Lecythidaceae)

This six-month study examined percent germination, days until germination, and early seedling survival of Gustavia superba (Lecythidaceae) through field experiments in a tropical moist forest in Panama. The study had three goals: (1) to examine whether germination is a factor determining density of seedlings at three forest sites with different ages; (2) to test whether burial of seeds affects germination; and (3) to test if microsite conditions associated with light gap, gap-edge, or forest understory influence germination. The experiment, which was designed to fit a three-way ANOVA model, used three study sites, three microsites, two burial treatments, four replicates and 25 seeds in each replicate (1800 seeds total). Although seedling densities of G. superba at the forest sites varied inversely with age of forest, there was no evidence that germination success contributes to this pattern. Results indicated that this species germinates readily under most conditions: the overall mean was 85.4 percent and only six of 72 plots had less than 70 percent germination. Germination percent was reduced and mean number of days until germination was increased in the largest light gap. However, percent germination and days until germination did not differ among sites when only seeds in the understory microsite were compared. Burial of seeds and microsite conditions had minor effects on germination. Seedling mortality occurring soon after germination was not large (5.7%). It is concluded that G. superba is not a tropical species whose seeds germinate in response to a light gap but its seeds do germinate successfully under a range of microsite conditions. ALTHOUGH PLANT POPULATION SIZES can be affected by mortality at many stages, the seed to seedling transition generally is considered to be one of the most vulnerable. Mortality agents include pathogens, insect and vertebrate predators of seeds, as well as abiotic factors affecting germination levels. All these factors are intertwined in affecting seedling establishment. As a result, controlled experiments are required to identify the separate contribution of each factor. The focus of this paper will be to discuss the role of germination per se in seedling establishment of Gustavia superba (Kunth) Berg (Lecythidaceae), a