Phenology

By

Scott A. Mori and G. T. Prance


Copyrighted 1987 by The New York Botanical Garden, Bronx, New York 10458-5126. Reprinted with permission from the Memoirs of The New York Botanical Garden 44: 124-136. 1987. Please report comments and corrections to Scott A. Mori (smori@nybg.org).

| Abstract | Introduction | Methods | Results|
| Corythophora | Couratari | Eschweilera | Gustavia | Lecythis |
| Discussion | Acknowledgements | |Literature Cited | Addendum |
| Fig. XI-1 | Fig. XI-2 | Fig. XI-3 | Fig. XI-4 | Fig. XI-5 |

Abstract

The climate of Saül is characterized by a well-defined dry season from August through November and a wet season for the remainder of the year. Here, the Lecythidaceae bloom predominately during the dry season-early wet season, and their seeds become mature in the early to mid wet season. Three phenological patterns are seen amongst species of this family: 1) leaf drop, leaf flush, flowering; 2) leaf drop, flowering, leaf flush; and 3) leaf drop and flowering are independent of one another. Species of Lecythidaceae in the vicinity of Saül either produce a few flowers daily over long periods ("steady state" flowering), abundant flowers daily over short periods ("big bang " flowering) or abundant flowers daily over long periods ("cornucopia" flowering). Throughout the dry season, species offering pollen and those offering nectar as pollinator rewards are in bloom at the same time, but the number of nectar-producers usually predominates. Species of the same genus with phenological overlap usually have other isolating mechanisms such as different floral structures, floral rewards, pollinators, or habitat preferences. For example, Corythophora amapaensis and C. rimosa subsp. rubra flower at the same time, but their different floral structures attract different bees, principally euglossines in the former and meliponids in the latter. On the other hand, species with similar floral biologies and habitat preferences are often, but not always, phenologically separated. Although flowering species of Lecythidaceae occurs mostly throughout the dry season and into the early wet season, fruit maturation of all dry season bloomers takes place at the beginning of the wet season, presumably to take advantage of the increased moisture, nutrients, and gap opportunities available at that time of year.

Introduction

Botanical phenology is the study of the timing of vegetative activities, flowering, and fruiting and their relationship to environmental factors. In recent years there have been numerous contributions to our knowledge of the phenology of lowland neotropical forests (Alencar et al., 1979; Alvim & Alvim,1978; Croat, 1969; Daubenmire, 1972; Foster, 1982; Fournier & Salas, 1966; Frankie et al., 1974; Jackson, 1978; Janzen, 1967; Mori et al., 1982; Sabatier, 1985; Smythe, 1970). Nevertheless, there are few studies that consider the phenologies of individual families, the work of Gentry (1974) being the exception. In the Lecythidaceae, Mori and Kallunki (1976) made a detailed study of Gustavia superba (Kunth) Berg; Mori et al. (1980) examined Lecythis pisonis Cambess.; and Prance and Mori (1979) summarized what was then known about the phenology of Neotropical members of the family. Recently, Sabatier (1983, 1985) has studied the phenologies of all species of Lecythidaceae in a forest near St. Elie, French Guiana.

Because phenological events are dependent on climate, the following discussion of the climate of the Guianas, with special reference to that of French Guiana, is presented below.

In Surinam there are four seasons, a long dry from August through November, a short wet from December to January, a short dry from February to March, and a long wet from April through June (Schulz, 1960). These are the basic seasons, but they are subject to yearly and geographic modification throughout the Guianas. For example, to the west into Guyana, the short dry season becomes more pronounced, and to the east, especially in eastern French Guiana, rainfall increases and the short dry season is less distinct or even absent. Even in Surinam, the short wet season may be absent in some and the short dry season absent in other years, producing dry and wet years respectively (Schulz, 1960)

Rainfall in French Guiana is influenced by the relative position of the Intertropical Convergence Zone (ICZ). During the driest part of the year, August to September, the ICZ lies to the north of French Guiana. By November, still a time of generally good weather but with risk of showers, the ICZ has reached northern French Guiana. From December to June, the period of heaviest rain, the ICZ is found directly over French Guiana. As the ICZ moves northward in July the rains lessen and there is a transition into the long dry season. Periods of dry weather may also occur in February and March when the ICZ is farthest to the south which results in a short dry season (Paul, 1981). Movements of the ICZ produce a generalized climate in French Guiana very much like that described above for Surinam.

Monthly average rainfall for Saül, based on data from 1956-1975 (Paul, 1981) is represented in Figure XI-1. An average of 2413 mm of rain fell in these years. Rainfall from January 1982 to March 1983 (Fig. XI-1), the time of our study, paralleled that for the 1956-1975 period (data from the meteorological service of French Guiana which maintains a station at Saül). However, 1982, with 2287 mm of rainfall, was slightly drier. Moreover, the dry season was considerably more severe than in most years and the onset of heavy rains was somewhat delayed. Based on these data, it appears that there are two well-defined seasons in the vicinity of Saül, a dry season from August through November and a wet a season from December through July.

Temperature is relatively constant throughout the year (Fig. XI-1) with the daily fluctuation greater than the annual. In 1982, the average annual monthly temperature was 27.1C and the average monthly minimum and maximum temperatures were 20.9C and 31.5C, respectively (data from the meteorological service of French Guiana). The difference between the longest and shortest days of the year is approximately 35 minutes (List, 1950).

Methods

The phenologies of the species of Lecythidaceae reported herein are based on two periods of observation. The first from 6 Aug to 11 Dec 1982, included most of the dry season of 1982, and the second, from 25 Mar to 1 May 1983, was at the onset of the first heavy rain of the year. All marked Lecythidaceae (210 individuals) found along La Fumée trail system (Table V-I and Figs. V-1-6) were observed during most of the dry season and early wet season for the presence of flowers and fruits. These trees were visited about every two weeks from 4 Sep to 11 Dec 1982 and were revisited in March and April of 1983. These data were supplemented by observations of non-marked trees growing in the vicinity of Saül and by examination of herbarium collections from throughout the ranges of the species, but especially from those collected in the Guianas. The number of flowering collections made in each month, based on collections of species of Lecythis and Eschweilera in the ORSTOM herbarium at Cayenne, was tabulated in December 1976.

Each species at the study site was examined to determine if it offered nectar or pollen as the pollinator attractant. The reader should bear in mind that all nectar reward species of Lecythidaceae also produce pollen. However, in these species, pollen plays a minor role in attracting pollinators in comparison to that of nectar. In order to show the relative abundance of pollen and nectar reward species in bloom throughout the dry season, the number of species in flower offering each was tabulated for each observation period (Fig. XI-2). Lecythis poiteaui, a bat-pollinated species which offers nectar and perhaps pollen, was not included in the tabulation. Lecythis corrugata subsp. corrugata was considered a pollen reward-producer even though it may offer some nectar and L. confertiflora a nectar reward-producer even though it may offer some pollen. For further discussion of pollinator rewards see Chapter XII.

The number of flowers produced daily at peak flowering was estimated for each species, and leaf drop and flush in relation to flowering was determined.

Results

At La Fumée Mountain, species of Lecythidaceae bloom predominately in the dry season (including the dry season to wet season and wet season to dry season transitions) (Figs. XI-3, 4). The number of species in flower in 1982 for each observation period during the dry season ranged from nine (39% of the species under observation) to 16 (70%). Consequently, there is a relatively large number of species of Lecythidaceae in flower throughout the dry season (Fig. XI-2). Further into the wet season, at the time of the first really heavy rains in March-April 1983, only Gustavia hexapetala was in flower. In May (one of the wettest months) 1986, only a few individuals of Couratari multiflora were seen in flower. Consequently, flowering of Lecythidaceae during the peak of the wet season is considerably reduced.

The number of individuals of Lecythidaceae in flower throughout the dry season is also high, with the peak of 15 November caused by the simultaneous flowering of two nectar reward-producers, Couratari stellata and Eschweilera micrantha (Figs. XI-3, 4). An examination of the number of flowering collections of Eschweilera and Lecythis at CAY in 1976 indicates that these two genera are dry season bloomers (Fig. XI-5) thereby supporting the findings of the current study.

Nectar-producing species of Lecythidaceae in flower at any given time always outnumber those which offer pollen as a reward. Nevertheless, at least three pollen-producing species were throughout our dry season observations (Fig. XI-2).

Most species of Lecythidaceae dropped seed, developed from flowers of the previous dry season, in the early to mid wet season from 12 Dec 1982 to 15 Mar 1983. Exceptions were Couratari multiflora and Eschweilera pedicellata which dropped some seed in the dry season, E. decolorans and E. grandiflora which had nearly mature seed before the end of the dry season, and Lecythis holcogyne and Gustavia augusta which were still dropping seed well into the wet season in April. However, none of the species of Lecythidaceae at La Fumée Mountain are known to drop significant numbers of seeds during the dry season.

The phenologies of the species of each genus are summarized below.

Corythophora

Corythophora rimosa subsp. rubra is a canopy tree that produces up to 100 flowers daily and blooms for one to two months (Fig. XI-3). Although we marked 12 trees of this species, only three of them produced flower and none were found with seed during our study. Corythophora ampaensis, also a canopy tree, produces up to 50 flowers daily for two to three months. The two trees we studied of this species flowered simultaneously in the dry season and tree 830 dropped seed in April. Both species of Corythophora occupy the same stratum, grow in the same habitat, flower at the same time, produce relatively high numbers of flowers for a long time ("cornucopia" species), and retain their leaves at flowering. However, their flowers are different in size and structure, and they are visited by different pollinators (Chapter XII).

Couratari

Couratari multiflora is an emergent tree that produces hundreds of flowers daily for a relatively short but undetermined period ("big bang" species). It flowers at the onset of the dry season and drops seed toward the end of the dry season. This species flowers while leafless as is common in several species of this genus. Couratari stellata, another emergent, produces hundreds of flowers daily for one to two months ("cornucopia" species). It flowers, while retaining its leaves, from mid dry season into the first part of the rainy season (Fig. XI-3) and drops seed in the wet season. Another species, C. gloriosa, did not occur as a marked tree, but it is found frequently along streams in other parts of the vicinity of Saül. We have collected seeds and seedlings of this species from trees with newly flushed leaves in April (Mori & Pipoly 15627, 15690, 15693). Moreover, herbarium collections with flowers have been made of this species in the Guianas in February and March. Consequently, it appears that C. gloriosa drops leaves and flowers at the beginning of the wet season and matures seeds during the first months of the wet season. We have no observations on the phenology of C. guianensis, which occurs infrequently at La Fumée Mountain, but observations from other parts of its range, where it is often common, indicate that it drops its leaves, flowers profusely for a short period, and then flushes new leaves.

From our observations, it is apparent that two phenological patterns have evolved in Couratari. The first, represented by C. stellata, is the production of many flowers for a relatively long period (several months) ("cornucopia" flowering). The second, represented by C. multiflora, C. gloriosa, and C. guianensis, is the massive production of flowers in the absence of leaves for relatively short periods ( less than twelve days) ("big bang" flowering).

Eschweilera

Three of the 11 species of Eschweilera in the study area are understory trees. Individuals of E. grandiflora produce few flowers daily for one to two months, and the species blooms from the late dry season into the wet season (Fig. XI-4). By early December some fruits had reached mature size and all seeds of this species had dropped before the end of March. Trees of E. pedicellata produce several to fewer than 100 flowers daily for one to three months. The species blooms throughout the dry season (Fig. XI-4) and drops seed from the end of the dry into the wet season. Individuals of E. parviflora produce up to several hundred flowers daily for several weeks. The species blooms from the late dry season into the early wet season (Fig. XI-4) and drops seed sometime during the early part of the wet season.

The other eight species of Eschweilera found at La Fumée Mountain are canopy trees. Individuals of E. collina produce a few flowers daily for about one month; the species blooms throughout the dry season. We found flowers under several trees at the end of August and one marked tree (953) came into full flower on 4 October. By early November we had found fresh opercula from tree 893 which must have developed from an early dry season flowering. It is noteworthy that all flowering collections of this species from the Guianas have been gathered from July to November which conforms to the dry season throughout the region. Trees of E. coriacea produce several hundred flowers daily for several to six weeks, with the species blooming from the late dry to the early wet season (Fig. XI-4). At the end of flowering, most aborted ovules fall simultaneously and attract animals, which eat them. On 29 November, 35% of the marked trees of this species showed disturbance on the ground under the crowns as a result of this feeding. We observed abundant seed fall of E. coriacea in the wet season in late March through April. Individuals of E. decolorans produce up to several hundred flowers daily for one to two months, and the species blooms from the early to mid dry season (Fig. XI-4). All seven marked trees of this species were in flower at the start of the study, but by 1 November no trees were blooming. Many fruits had reached mature size by late November-early December, and all fruit had dehisced by late March indicating that seed had been dispersed in the early wet season. Trees of E. micrantha produce several hundred flowers for several weeks to several months. The species blooms from the late dry into the early wet season (Fig. XI-4), and its seeds drop at the beginning of the wet season. Individuals of E. squamata produce hundreds of flowers daily for one to three months. The species blooms throughout the dry into the early wet season (Fig. XI-4). We observed abundant seed under tree 845 in the rainy season in late March and April. Trees of E. apiculata produce hundreds of flowers daily for one and one-half months. The species blooms in the mid dry season (Fig. XI-4) and drops seed sometime during the early wet season.

All species of Eschweilera retain their leaves throughout the year, and there is no apparent leaf loss or flush in conjunction with flowering.

In summary, the species of Eschweilera display two phenological patterns, that of relatively few flowers over relatively long periods ("steady state") flowering: E. collina, E. grandiflora, E. pedicellata) and that of abundant flowers over relatively long periods ("cornucopia" flowering: the remainder of the species studied). There is a tendency for understory species to display "steady state" flowering whereas canopy and emergent species are most often "cornucopia" bloomers. Exceptions are the "steady state" canopy series, E. collina and the "cornucopia" understory species, E. parviflora.

Gustavia

Both species of Gustavia at La Fumée Mountain, as well as most species of the genus, are understory trees. Trees of G. augusta produce one to six flowers daily for up to three months. Tree 818 was observed in flower for most of the dry season. It flowered sporadically from 7 August to 21 September and then began to drop one to six flowers daily until 15 November, after which it flowered sporadically until at least 11 December. When we reinitiated observations in the last week of March, trees 1002, 1004, and 1005 were found with nearly mature fruits, indicating that these individuals must have bloomed sometime between mid-December and the end of March in the early wet season. Individuals of G. hexapetala produce several to 20 flowers daily for several weeks to two months. Trees 804, 812, 820, and 827 produced no or only sporadic flowers during the dry season, but tree 812 came into full flower at the onset of heavy rains and three new trees in full flower (1003, 1006, 1007) were marked then. Moreover, several other trees of this species outside of the trail system were observed to flower at this time. Gustavia hexapetala was the only species of the family in flower well into the rainy season. All but one of the 24 flowering collections of this species that we have studied from the Guianas have been gathered in the dry or early wet season.

Both species of Gustavia retain leaves throughout the year, and there is no apparent relation between flowering and leaf fall or flush.

In summary, the two species of Gustavia found in the study are understory trees. Gustavia augusta blooms throughout the dry season and G. hexapetala blooms well into the wet season. They produce relatively few flowers daily for a long period and therefore must be considered "steady state" bloomers.

Lecythis

All species of Lecythis found in the study area are either canopy or emergent species. Two of the species, L. zabucaja and L. poiteaui, lose their leaves and then flower and flush new leaves simultaneously. At peak flowering, trees of L. zabucaja produce hundreds of flowers daily for an undetermined period. Five of the eight trees we marked flowered, but only one of these bloomed profusely. The others dropped sporadic flowers for several weeks and then stopped flowering. Observations of the crowns of several trees in April revealed a low number of nearly mature fruits in each. Nineteen of the 23 flowering collections of L. zabucaja from throughout its range have been gathered in June to September, suggesting that this species blooms during the late wet into the early dry season. Its fruits mature in the wet season from March to June. Individuals of L. poiteaui produce up to 700 flowers daily for one to four months from the early dry into the wet season (Fig. XI-3). Eighteen of the 20 flowering collections available from throughout its range were gathered from November to February, which suggests that flowering is more profuse from the late dry season into the first months of the wet season. Only three of the seven trees we marked for this study bloomed, and even these individuals produced fewer flowers than we observed in 1976 (Mori et al., 1978). Several additional trees dropping seed and several others with nearly mature fruit were found in April, indicating that they had flowered in our absence, during the early part of the wet season.

The remaining species of Lecythis retain their leaves throughout the year, and there is no apparent relationship between flowering and leaf fall or flush. Individuals of L. corrugata produce up to 500 flowers daily for an undetermined period, and the species blooms at the end of the dry into early wet season. We marked five trees of this species starting on 8 November, and all five were still in flower on our last day of observation (11 December) (Fig. XI-3). Upon our return in late March flowering had ceased and most of the seeds had dispersed. At this time, a few green fruits found in tree 807 (Mori & Pipoly 15595) possessed aborted seeds. Trees of L. holcogyne produce less than one hundred flowers daily for an undetermined period. Tree 1001 was found in flower at the beginning of the wet season, another unmarked tree was observed at the end of flowering in late March, and abundant seed was found under tree 1001 (Mori 7 Pipoly 15493) at the beginning of April. These observations suggest that L. holcogyne flowers and matures seed in the first part of the wet season. Individuals of L. persistens produce up to several hundred flowers for at least one to two months. The species includes two subspecies, subsp. persistens and subsp. aurantiaca, but only the former was found along La Fumée trail system. We first observed trees of subsp. persistens in flower on 1 November, and all three marked trees were in full flower by our departure on 11 December (Fig. XI-3). Mature seed was dropped in March and April. We collected subsp. aurantiaca in full flower (Mori et al. 15075, 15076) on 10 October along the Carbet Maïs Trail, and noted that several had dropped all of their seeds prior to late March. These limited observations suggest that subspp. aurantiaca and persistens are phenologically separated, the former flowering and dropping seed earlier than the latter.

Trees of L. confertiflora and L. idatimon produce hundreds of flowers for one to two months. They are phenologically separated. Lecythis confertiflora blooms from early to mid dry season and L. idatimon from the late dry season into the wet season (Fig. XI-3). Moreover, L. confertiflora had dropped all of its seed by March, whereas seeds of L. idatimon were still being dispersed then. This phenological separation holds in other parts of the range of the two species. For example, in Amapá the senior author has collected L. confertiflora in fruit and L. idatimon in flower from the same habitat in January.

In summary, species of Lecythis of La Fumée Mountain display two phenological patterns, leaf drop followed by leaf flush and flowering (L. poiteauti, L. zabucaja) and, flowering independent of leaf flush (the remainder of the species). All the species studied produce high numbers of flowers for relatively long periods ("cornucopia" species) and, for the most part, bloom in the dry season or early part of the wet season. All the species studied drop fruit in the wet season, especially within the first few months after the onset of heavy rains.

Discussion

Flowering of the Lecythidaceae of La Fumée Mountain occurs in the dry season and the early part of the wet season. All the species for which we have data either flower entirely within the dry season or initiate flowering during the transition from the dry into the wet season or from the wet into the dry season (Fig. XI-3, 4). Flowers of Lecythidaceae on the ground are conspicuous because of their presence in the dry season in contrast to their absence in the wet season. It is becoming increasingly apparent that in Neotropical forests with a dry season, peak flowering in trees occurs then (Alencar et al., 1979; Croat, 1969; Fournier & Salas, 1966; Frankie et al., 1974; Janzen, 1967; Sabatier, 1985). Gustavia superbra (Mori & Kallunki, 1976), Lecythis pisonis (treated as L. usitata), and Cariniana micrantha Ducke (Prance & Mori, 1979) are other Lecythidaceae, outside the range of this study, which have been shown to flower in the dry season. More importantly, Sabatier (1983, 1985) has demonstrated that all the species of Lecythidaceae at his study site near St. Elie, French Guiana flower in the dry season. However, it should be noted that in Neotropical lowland forests, and in Lecythidaceae, some flowering may be found at all times of the year (Mori et al., 1982).

In Neotropical forests in which there is no dependable annual dry season, flowering may be triggered by other factors, such as increasing photoperiod and temperature. For example in southern Bahia, where there is no predictable annual dry season, peak vegetative and reproductive activity in trees occurs with the increasing day lengths and temperatures of the spring (Mori et al., 1982). Here, Lecythis pisonis is a harbinger of spring, flowering year after year in that season regardless of annual rainfall fluctuations (Mori et al., 1980).

Seed drop of Lecythidaceae at La Fumée Mountain occurs mostly in the first few months of the wet season. If a species fruits in the dry season, as does E. pedicellata, fruit maturation and seed fall take place towards the end of this season. Sabatier (1983) found that all ten species of Lecythidaceae that he studied matured seed from December to April in the early to mid wet season.

The seeds of Lecythidaceae are generally large, have a relatively soft testa, and germinate shortly after dispersal. Exceptions are the smaller, winged seeds of Cariniana and Couratari and the very hard testa of the Brazil nut (Bertholletia excelsa Humboldt & Bonpland). Species of the former two genera, like typical Lecythidaceae, germinate soon after falling, however, whereas those of B. excelsa may remain dormant for up to a year (Prance & Mori, 1979). Consequently, the seeds of all but B. excelsa cannot withstand prolonged drought without a drastic reduction in seed viability.

Smythe (1970) has demonstrated a pronounced peak production of large animal-dispersed seeds at the end of the dry season into the early wet season in Panama. This also holds for the large seeds of Gustavia superba in the same area (Mori & Kallunki, 1976). In 1983, during the first months of the wet season at La Fumée Mountain, there was abundant production of fruit, especially of species of Burseraceae, Lecythidaceae, and Sapotaceae. The correspondence of seed drop with the rainy season insures that seedlings will be provided with sufficient water for their germination and growth. It enables them to utilize the influx of nutrients released from accumulated litter over the dry season and additional light caused by the higher frequency of tree falls at the beginning of the wet season. Sabatier (1983) has suggested that mass fruiting of Lecythidaceae may satiate predators, thereby insuring that at least some seedlings become established.

The winged seeds of Couratari multiflora are released in the late dry season whereas those of C. gloriosa and C. stellata fall in the early wet season. Although conditions of the dry season are often thought to favor wind dispersal, the squalls of the wet season may be equally effective in dispersing winged seeds.

Prance and Mori (1979) have recognized three phenological patterns in the Lecythidaceae: 1) leaf drop, leaf flush, flowering; 2) leaf drop, flowering, leaf flush; and 3) leaf drop independent of flowering. At La Fumée Mountain, Lecythis zabucaja and L.poiteaui have the first; Couratari guianensis, C. gloriosa, and C. multiflora the second; and the remaining species the third phenological pattern. The second type includes species with massive flower production over a short period and has been referred to as the "big bang" flowering strategy by Gentry (1974). Couratari guianensis, C. gloriosa, and C. multiflora possess dark pink flowers which, when produced massively in a leafless crown, may serve to attract pollinators. The second and third phenological types include species that either produce few flowers ("steady state") or many flowers ("cornucopia"), both for relatively long periods. Eschweilera grandiflora, E. collina, E. pedicellata, Gustavia augusta, and G. hexapetala are "steady state," whereas the remainder of the species are "cornucopia" bloomers. It is noteworthy that only emergent trees are "big bang" species, and that most of the "steady state" species are understory trees. Canopy species are usually, "cornucopia" bloomers. Moreover, "big bang" species only offer nectar whereas "steady state" and "cornucopia" species may offer pollen or nectar or both.

It is well known that tropical trees vary in their phenological responses from year to year. Some species bloom every year, some several times in a year, some every two years, and others at longer intervals (Alencar et al., 1979). Prance and Mori (1979) and Mori et al. (1982) have shown that individuals of Lecythis pisonis (cited as L. usitata in the former paper) vary in number of flowers produced from year to year and that some trees fail to flower in some years. It is general knowledge throughout Amazonia that a year of heavy fruit production by a Brazil nut tree will be followed by reduced flowering in the next year. Our failure to observe profuse flowering in L. zabucaja might be because 1982-1983 was a year of limited flowering for this species. This emphasizes the need for long-term phenological studies in order that more accurate phenological patterns can be determined.

If different species of a genus flower at different times, the opportunities for cross pollination between them are greatly reduced even if they are interfertile. Therefore, species of a given genus may occur together provided that they flower during different periods. This phenomenon may allow the co-existence of more species within a given community than would be possible otherwise.

Gentry (1974) has shown that the seven Central American species of Arrabidaea (Bignoniaceae) have separate floral phenologies. Within individual genera of Lecythidaceae of La Fumée Mountain, some species show phenological overlap whereas others are separated. Species of a given genus of Lecythidaceae that flower at the same time generally exhibit other features that reduce the probability of cross pollination between them. For example, Corythophora amapaensis and C. rimosa, although flowering at the same time and occupying the same stratum and habitat in the forest, have different size flowers and offer their pollen reward to bees in different positions within the flower. Euglossine bees are the dominant pollinators in the former and meliponid bees the dominant pollinators of the latter species (Chapter XII).

Commonly, species of a genus of Lecythidaceae with similar floral biologies and ecologies are phenologically separated. A striking example is Eschweilera pedicellata and E. grandiflora, both understory species producing nectar as the pollinator reward. The former blooms from the early to late dry season whereas the latter flowers from the late dry into the wet season (Fig. XI-4). Likewise, E. decolorans and E. coriacea have identical flowers and ecologies, but the former blooms earlier than the latter (Fig. XI-4). Nevertheless, in both cases some overlap in flowering does occur (Fig. XI-4) but clear examples of hybridization are not apparent.

Phenological separation in similar species does not always occur. Eschweilera decolorans and E. laevicarpa phenologically overlap even though their habitat preferences and flowers are nearly identical. These species can only be separated by fruit and bark characteristics. (Chapter IV).

Much more information on the reproductive biology of Lecythidaceae is needed. In particular, we need to know what kinds of genetic barriers exist between species. Consequently, the conclusions of this chapter are based on an incomplete knowledge of all of the factors important in species isolation.

Acknowledgements

We are grateful to Brain M. Boom for his help in gathering the data upon which this paper is based and to Carol Gracie for her review of the manuscript. We also thank Bobbi Angell for the preparation of the graphs.

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Addendum

At the time of the preparation of this paper, Lecythis confertiflora and L. idatimon were considered as subspecies of L. idatimon. The recognition of them as species will slightly alter the values presented in the text and figures but in no way changes the conclusions of this paper.


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