COMPARATIVE REPRODUCTIVE BIOLOGY OF ALPINE BIENNIAL AND PERENNIAL GENTIANS (GENTIANA: GENTIANACEAE) IN CALIFORNIA

Reproductive characteristics of three sympatric species of Gentiana exhibiting perennial and non-perennial life histories were studied in alpine meadows of the White Mountains of California during three consecutive years. High fruit and seed set and the production of a relatively large number of seeds characterized the alpine biennials, Gentiana tenella and G. prostrata. In contrast, fruit and seed set were considerably reduced and yearly seed production was relatively low in the alpine perennial, G. newberryi. Successful seed production in the biennial species was a result of low rates of flower predation, self-pollination, and the allocation of a comparatively high proportion of biomass to reproductive structures. Seed production in the perennial species was limited by high rates of flower predation, insufficient amounts of pollen reaching stigmas, an unusually late flowering period, and by the relatively small proportion of biomass allocated to reproduction.     

Effect of ovular receptivity on seed set and fruit development in cucumber (Cucumis sativus L.)

Summary Seed set and fruit development in cucumber (Cucumis sativus L.) were studied in relation to female flower receptivity from day — 2 before anthesis to day + 2 after anthesis. The female cucumber flower is protogynous. The pistil was receptive 2 days before anthesis. The iso-electric focusing (IEF) patterns of the stigma/style proteins, were identical from day -5 to day +2. In pollinated flowers in vivo germination and pollen-tube growth in the ovary were affected by pistil age from day -2 to day +2. In addition, differences in sectorial filling in full seeds were observed within the fruits. A negative correlation was observed between the frequency of fertilized ovules in the pedoncular part of the fruit and ovary length at the time of pollination. In the whole fruit, significant differences in the number of full seeds and fruit size at maturity were found, and these were observed to be correlated with the various stages of female flower maturation at pollination. The day -2 and day +2 stages yielded the smallest fruits with few full seeds compared to the day -1, day 0 and day +1 stages, which had the biggest fruits and a large number of full seeds. A strong positive correlation was found between total seed number (including full and empty seeds), fruit length and weight at maturity. All these results suggest that both seed set in the different parts of the fruit and fruit development are controlled by ovular receptivity rather than by stigma/style receptivity.     

NONFRUITING HERMAPHRODITIC FLOWERS OF CALOCHORTUS LEICHTLINII (LILIACEAE): POTENTIAL REPRODUCTIVE FUNCTIONS

The breeding system, flowering display, and fruiting pattern of Calochortus leichtlinii Hook. (Liliaceae) was studied in the eastern Sierra Nevada. This species is capable of both autogamy and insect-mediated outcrossing. Either of these two means of pollination alone could affect full seed set; the populations studied were not pollination limited in 1983. Most individuals produced two flowers but set only one fruit. Flowers are not selectively matured on the basis of the quantity or purported quality of the pollen they receive; the first flower to open was matured in all experiments. Nonfruiting flowers have at least three potentially important reproductive functions: disseminating pollen, allowing plants to produce more seeds in response to an abundance of soil moisture, and setting seeds if the first flower fails to develop fruit.     

FLOWER,FRUIT AND SEED ABORTION IN TROPICAL FOREST TREES: IMPLICATIONS FOR THE EVOLUTION OF PATERNAL AND MATERNAL REPRODUCTIVE PATTERNS

Flower, fruit and immature seed abortion was studied in seven self-incompatible species of trees in a tropical lowland semideciduous forest. The species showed considerable variability in fruit and seed set and the rate at which flowers and fruits were aborted. The amount of flower and fruit abortion also varied over time within species. Small samples of open-pollinated flowers in three species showed adequate amounts of pollen on the stigma, but it could not be determined whether the pollen was compatible or incompatible. In a species with multiseeded fruits, the aborted fruits contained significantly fewer seeds than those retained on the plant. Position of fruit within the inflorescence and of seed within the ovary also had a marked effect on abortion: fruits and seeds at certain positions had a higher probability of abortion than those at other positions. Experiments to test the effect of pollen source on abortion were inconclusive. The factors underlying abortions were evaluated in the context of three mutually non-exclusive hypotheses. It is concluded that selection for increased pollen dispersal and uncertainty in paternity of the zygotes are major factors underlying abortions.     

Pollen limitation in three sympatric species ofVaccinium (Ericaceae) in the Upper Ardennes, Belgium

The reproductive success of three co-flowering species ofVaccinium (V. myrtillus, V. vitis-idaea andV. uliginosum) was studied in one heathland of the Upper Ardennes, Belgium, during three years (1988–1990). The purpose was to examine whether pollen limitation, flower position and flowering phenology may influence patterns of fruit set in these three sympatric species. I quantified fruit and seed set following supplementary hand-pollinations and compared this to natural fruit set. On the same plants, I also quantified fruit and seed set in relation to the spatial position of the flowers on the ramet and their temporal sequence of blooming. Hand-pollination had no significant effect on fruit set inV. vitis-idaea andV. uliginosum, but significantly increased seed number per fruit in 1989. InV. myrtillus both fruit and seed set were increased by supplementary pollination, but significantly in only one year. Analyses of position effects revealed that the fruits in the lower positions in the ramet did not mature preferentially and did not contain more seeds inV. uliginosum and inV. vitis-idaea. Flowering phenology also had no significant effect for these species. InV. myrtillus hand-pollinated flowers showed a seasonal decline in seed number, and control (naturally pollinated) flowers showed a seasonal increase in fruit set. Fruit and seed set appear to be pollen-limited rather than resource-limited inV. uliginosum. In the two other species, unfavorable weather (frosts) could be a more important cause of low fruit and seed set.     

Persistence of flower visitors and pollination services of a generalist tree in modified forests

Flower‐visiting insects provide essential pollination services to many plant species. It is thus of critical importance to understand the effects of anthropogenic landscape modification on these animals. Particularly at the landscape scale, we still lack information on how flower visitors are affected by different intensities of human disturbance. In this study, we chose six representative types of forest modification across a heterogeneous South African landscape. At 36 study sites we observed insect visitation to Celtis africana flowers in two consecutive years. This generalist tree species has small unspecialized flowers which we found to be pollinated by a diverse array of insects as well as by wind. Visitation rates to flowers of C. africana differed significantly among the six forest types and between two study years. Visitation rates were enhanced in modified forests, facilitated by a high abundance of feral honeybees (Apis mellifera). Fruit set in C. africana showed significant positive associations with insect visitation and with the diversity of flower visitors, but was only weakly predicted by forest type. Our findings imply that even though forest modification can strongly alter flower visitors, pollination services for trees with unspecialized flowers may persist at a landscape scale. We advise conservation managers to maintain modified forest fragments in addition to natural forests as these may contribute to sustain pollination services in human‐modified landscapes.     

SOME OBSERVATIONS ON THE REPRODUCTIVE BIOLOGY OF GAULTHERIA PROCUMBENS (ERICACEAE)

The pollination and fruit production of Gaultheria procumbens L. (Ericaceae), an evergreen sub-shrub, were studied in five woodland sites in New Jersey and one in northeastern Pennsylvania. Pollinator exclusion methods at three of the sites produced no consistent differences in fruit and seed set between enclosed plants and controls. Insect pollinators, almost exclusively bumblebees, were sparse at all sites; visitation rates were about 0.01 bee visits/flower/hr. All fruits examined contained at least 35 seeds, but about half of the pistils examined, from open-pollinated plants, did not contain enough pollen tetrads on their stigmatic surfaces to fertilize this number of ovules. However, the low average fruit set of 8.2% on open-pollinated plants was due more to the high mortality of buds prior to anthesis than to inadequate pollination. Bud mortality was high and fruit set low in 3 years of observations at various study sites, indicating that this may be a general pattern for the species in northeastern United States and adjacent Canada. The amount of sexual reproduction showed no consistent relationship to stem density.     

Assessment of reproductive characteristics of Jatropha curcas L. in south Florida

Jatropha curcas L. (jatropha) is a species identified for biofuel production because of the high quality of the oil produced by its seeds. However, jatropha is undomesticated and little information is available about its reproductive characteristics. Breeding and genetic improvement programs are much needed for the jatropha development as a bioenergy crop. Information about floral display and mode of reproduction are considered essential for breeding programs. In this study, the total number of female flowers, male to female flower ratio, fruit set, in vitro pollen germination, and the formation of fruits by apomixis, self‐pollination, and natural pollination were evaluated in 17 jatropha accessions planted in South Florida. The total number of female flowers per inflorescence and male to female flower ration ranged from 2.8 to 9.1 and 9.9:1 to 55.4 : 1, respectively. During summer 2011, high fruit setting average was observed (75.5%). In vitro pollen germination varied from 64.6% during spring 2011 to 51.6% during fall 2011. The fruit set observed was from 10.1% to 64.0% through natural pollination and apomixes, respectively. Characteristics such as fruit fresh weight, number of seeds per fruit, seed dry weight, and oil content were influenced by mode of reproduction.     

Influence of reproductive traits on pollination success in two <Emphasis Type="Italic">Daphne</Emphasis> species (Thymelaeaceae)

Taxonomically related species can differ in a number of reproductive traits, which may translate into a differential mating system and pollination success. Here we compare two hermaphroditic insect-pollinated Daphne species (D. rodriguezii and D. gnidium) which differ in distribution (island endemic vs. mediterranean) and floral traits (long- vs. short-tube corolla). We investigated their mating system and pollen limitation by means of hand-pollination experiments and quantified the diversity and abundance of flower visitors by direct observations. Plant size and five reproductive traits (flower production, proportion of viable anthers, pollen production, flower tube length and tepal area) were studied to assess how they contribute to reproductive success, measured as proportion of pollen grains germinated per stigma and fruit set. Selfing was very low and pollen limitation existed in both species, though was higher in D. rodriguezii probably due to the scarcity of flower visitors. The low fruit set in both species suggests that most of the pollen grains found on stigmas are self-pollen. Pollinators appeared to favour some floral traits (specifically, flower tube length or tepal area) in both species, although flower crop in D. rodriguezii was the only reproductive trait influencing fruit set. In both species, the highest variability in reproductive traits and pollination success was within individuals. Our findings suggest that despite both species showed similar mating system, dependency on outcrossing pollen and selection of floral traits, pollen limitation was higher in D. rodriguezii, probably as a higher proportion of self-pollen arrives to its stigmas.     

Reproductive biology of the epiphytic bromeliad Werauhia gladioliflora in a premontane tropical forest

The floral phenology, fruit and seed production, and self-compatibility of Werauhia gladioliflora, an epiphytic bromeliad with a wide distribution, were studied in a premontane forest in the Monteverde area in Costa Rica. The species presents the pollination syndrome of chiropterophily, and it is visited by the small bats Hylonycteris underwoodi and Glossophaga commissarisi (Glossophaginae). The population flowering period extended from October to early December (end of rainy season) and seed dispersal occurred from February to April (dry season). Most plants opened a single flower per night, either every day or at one-day intervals during the flowering period. In natural conditions, the average fruit set amounted to almost half of the potential output, but individual fecundity (number of seeds) remained high. Seed number per fruit and germination capacity after artificial selfing and out-crossing treatments did not differ from natural pollination conditions. Werauhia gladioliflora exhibited high levels of autonomous self-pollination and self-compatibility at the individual and population level, characters associated with the epiphytic habitat. These reproductive traits are also associated with early colonizer species, yet life history traits, such as seed dispersal, seedling establishment success, and growth, are likely to have a major role in determining the presence of this species in the successional vegetation patches scattered over the studied premontane area.     

Comparison of insects and vertebrates as removers of seed and fruit in a Western Australian forest

Removal from the forest floor of seed or fruit of the six commonest species of trees in upland areas of the northern jarrah forest of Western Australia was studied experimentally. The smallest seeds (Eucalyptus marginata, Allocasuarina fraseriana) were taken by insects (presumably ants). Heavier seeds or fruits (E. calophylla, Banksia grandis, Persoonia longifolia, P. elliptica) were taken more often by vertebrates (presumably srrmll mammals). Seeds of E. calophylla and B. grandis were most preferred by vertebrates, possibly because they have the highest relative concentrations of nitrogen and phosphorus.     

Reproductive versatility in legumes: the case of amphicarpy in Trifolium polymorphum

Amphicarpy is a fascinating reproductive strategy, defined as fruit produced both below the soil surface and as aerial fruit on the same plant. Trifolium polymorphum is a grassland species subject to herbivory that combines amphicarpy with vegetative reproduction through stolons. Underground flowers have been described as obligate autogamous and aerial ones as self‐compatible allogamous, with aerial floral traits favouring cross‐pollination. In the present work we performed different pollination treatments on aerial flowers to analyse rates of pollen tube development and offspring fitness, measured as fruit set, seed production and germination percentage. This last variable was compared to that of seeds produced underground. No significant differences were found between fruit set in self‐ and cross‐pollinations. Seed production was higher in self‐pollinations, which is consistent with the higher rate of pollen tube development observed in self‐crosses. Spontaneous self‐pollination is limited in aerial flowers; thus pollen transfer by means of a vector is required even within the same flower. Germination tests showed that aerial seeds produced after self‐ and cross‐pollination did not differ in fitness, but underground seeds had higher germination percentage than aerial ones. Thus, we conclude that T. polymorphum has a mixed mating system. In grasslands with heavy grazing pressure, clonal propagation and underground seed production ensure persistence in the field. An intermediate level of selfing in aerial flowers ensures offspring, but morphological (herkogamy) and functional (dicogamy) floral traits maintain a window to incorporate genetic variability, allowing the species to tolerate temporal and spatial pressures.     

Reproductive biology ofFrangula alnus (Rhamnaceae) in southern Spain

Various aspects of the reproductive biology of the perennial hermaphroditeFrangula alnus Mill. were studied in two populations located in the province of Cádiz, southern Spain. Flowering extends from the second week of May to early July. The small, whitegreenish, entomophilous flowers are incompletely protandrous and last 8–10 days, but pollen transfer takes place only on days 1–3. A very weak, pleasant odour along with nectar and pollen attract over 45 insect species, of which 21 are probable pollinators. These are mainlyDiptera but also includeHymenoptera and the unusual (as flower visitors)Mecoptera. Reproduction is exclusively sexual and strictly xenogamous, with pollen transfer depending solely on insect vectors. Although flower morphology and individual flower phenology do not fully prevent self-pollination, and geitonogamy can easily take place, the level of autogamy was negligible. Therefore, some self-incompatibility mechanism is operative in this species. Only 2.8% of open-pollinated flowers set fruit. At the flower level, fruit initiation was apparently limited by availability of cross-pollen, which in turn seemed influenced by the structure of the population. The seed/ovule ratio in ripe fruits was ca. 50%. Predispersal (maternal) reproductive success (percent ovules becoming filled seeds) was 1.42%. For mature individuals this corresponded to ca. 430 to 1560 potential offspring per year.     

Diet and Geophagy Across a Western Amazonian Parrot Assemblage

We identified species‐ and community‐level dietary characteristics for a species‐rich Amazonian parrot assemblage to determine relationships among dietary metrics and use of geophagy sites. Previous studies suggest that soil is consumed at geophagy sites in this region mainly to supplement dietary sodium. We accumulated 1400 feeding records for 16 parrot species over 2 yr and found that seeds, flowers, and fruit pulp featured prominently in diets, while bark, insects, and lichen were consumed in small quantities. Food availability across 1819 trees was measured, and we found that flower availability was highest in the dry season and fruit production peaked in the wet season, but that phenology patterns of the 20 most commonly foraged plant species suggest no serious food bottlenecks. Partitioning of available food resources among the 13 most commonly encountered parrots is suggested by an ordination analysis (DCA), which placed the large macaws (Ara) with the Amazona parrots at the ‘primary forest’ end of a dietary resource axis and four smaller species at the ‘successional forest’ end of the axis. Parrot species associated with successional forest also consumed less plant species overall. Furthermore, these parrot species consuming successional forest resources had higher claylick visitation rates than those consuming primary forest resources suggesting they derive the greatest benefits from soil consumption.     

Between-year variation in flowering and fruit set in frost-prone and frost-sheltered populations of dioecious Rubus chamaemorus

Summary The flowering and fruiting patterns of the dioecious perennial herb Rubus chamaemorus L. were studied in frost-prone (open) and frost-sheltered (Shaded) habitats in northern Sweden over 6 years. The number of ramets with flower buds, the proportion of flower buds that opened, and fruit set varied markedly between years. In the frost-prone populations, the occurrence or absence of detrimental frosts during the development of flowers and fruit could explain much of the variation, both in the proportion of flower buds that developed into flowers, and in fruit set. In the frost-sheltered populations, most female flowers that did not develop into fruit aborted without any signs of physical damage and before any ovules had begun to enlarge. Flower mortality caused by herbivores feeding on reproductive parts was commonly low, but reached values higher than 10% in one of the shaded populations. Hand-pollination increased the proportion of ovules producing seeds in the mature fruits by about 20%, and in one year also increased fruit set significantly in one population. Fruit-producing female ramets had a higher mortality and a lower probability of flowering in the subsequent year than male ramets and non-fruiting female ramets. In R. chamaemorus, the conditions for fruit maturation are highly unpredictable at the time of flower initiation. It is suggested that the apparent over-initiation of flower buds is advantageous, as it allows the plant to attain a high reproductive success in years favourable for flowering and fruit development.     

Reproduction of invasive Amur honeysuckle (Lonicera maackii) and the arithmetic of an extermination strategy

Ecological restorations often require removal of invasive species. The abundance of invasives has tended to catalyze research emphasizing removal, not broader understandings, of species mechanisms for persistence in the landscape (e.g. reproductive output and seed dispersal). Asiatic shrub honeysuckles (Lonicera spp.) are pernicious invaders throughout eastern North America. Heavy tree canopy cover apparently reduces growth and reproductive output in Lonicera maackii, which is widespread through the lower Midwestern United States. To help focus control efforts more effectively, we quantified the effect of tree canopy cover on vegetative growth, flowering, and fruit production under three canopy densities. Mean vegetative growth of flowering shoots was not affected by canopy cover. All aspects of sexual reproduction (flower production, fruit set, fruit number, fruit mass, seed number, and seed size) were strongly reduced by moderate shade. Although all individuals modify community and ecosystem properties, a limited number of high light individuals might also provide the greatest proportion of the seeds. Through model simulation of honeysuckle population structure in relation to canopy cover, we argue that it can sometimes be more efficient to initially target reproductive individuals in the high light edge and interior gap environments than to immediately focus on all individuals in the forest interior.     

Costs of defense: correlated responses to divergent selection for foliar glucosinolate content in <Emphasis Type="Italic">Brassica rapa</Emphasis>

The evolutionary response of plant populations to herbivore imposed selection for defense may theoretically be constrained by the costs of defense, yet few studies convincingly demonstrate such costs. We investigated possible constraints on the evolution of defense in rapid cycling Brassica rapa by divergently selecting lines for investment in foliar glucosinolate content, a chemical defense in this species. Costs would then result in a significant correlated response to artificially imposed selection in the direction opposite to the direct response of foliar glucosinolate production. Correlated responses of date of first flowering, total flower number, number of seeds per fruit, and mean seed mass were examined. After three generations of selection, there was a significant direct response in glucosinolate content of the leaves of B. rapa. Furthermore, we found significant correlated responses in both total flower production and number of seeds produced per fruit, but not date of first flowering or mean seed mass. Lines selected for high glucosinolates produced fewer flowers and seeds per fruit compared to those selected for low glucosinolates while lines selected for low glucosinolates showed the opposite response. Thus, costs of defense were demonstrated and may constrain the evolution of foliar glucosinolate production in this plant species.     

Effect of nectar-robbing birds on fruit set of Fuchsia magellanica in Tierra Del Fuego: a disrupted mutualism

1. This paper investigates spatial habitat variation in flower visitation by avian pollinators (mainly Hummingbirds) and nectar robbers to Fuchsia magellanica at the southern limit of its range, Tierra del Fuego, and their effects on plant reproductive success.
2. The plant-pollination mutualism appears to be disrupted as Hummingbirds ( Sephanoides galeritus) are rare at this high latitude and the frequencies of a nectar-robbing bird ( Phrygilus patagonicus) are high, especially in open areas where F. magellanica is most abundant.
3. Nectar robbery by P. patagonicus reduced fruit set about 20%, mainly because this fringillid can damage the ovary when piercing a flower. This bird was more abundant in open areas than inside the forest and, as expected, flower piercing was also more frequent in the former habitat.
4. Spatial variation was also found in the frequency of flower visitation by Hummingbirds; these birds foraged chiefly in the forest presumably because of the greater probability of finding intact (non-robbed) flowers there. This suggests that cross-pollinations in this self-compatible plant are more likely to occur in the forest. Nectar robbers therefore may influence not only the quantity of seeds produced but also, indirectly, their quality.
5. Fuchsia magellanica is polymorphic in flower colour. Robbery was significantly lower in the pale than in the normal (red) morph, although fruit set was similar between morphs.     

The Structure of Ground Beetle Assemblages (Coleoptera: Carabidae) at Fruit Falls of Melastomataceae Trees in a Brazilian Terra Firme Rain Forest1

Although most Carabidae are recognized as predacious, recent studies have shown that some tropical rain forest Carabidae use the small seeds of fallen fruit from some tree species as a key food resource (particularly figs [Moraceae] but also those from other families). Assemblages of carabid beetles (Coleoptera: Carabidae) at fruit falls of the Melastomataceae tree genera, Bellucia, Loreya, and Miconia, were studied in a terra firme rain forest near Manaus (Amazonia, Brazil) from February 1992 to August 1996. Of 5483 specimens of 14 carabid species collected at 53 fruit falls, 98.2 percent of the collected beetles represented the seed-feeding genus Notiobia. Four of the 7 Notiobia species were found to reproduce at Melastomataceae fruit falls. The most abundant species, N. glabrata, was found to be a Melastomataceae seed generalise while N. maxima seemed to prefer the seeds of Bellucia, and N. aulica and Af. umbrifera the seeds of Miconia. The presence of larvae indicated reproduction of N. glabrata at fruit falls of all three tree genera and reproduction of N. maxima at those of Bellucia. Fruit falls of different species and genera of Melastomataceae appeared to occur at different times of die year and not continuously throughout the year. The seed-feeding Notiobia species, which specialize on Melastomataceae, used fruit falls of figs as migratory “stepping stones” during periods when there were no Melastomataceae fruit falls. The comparable suite of fig seed-feeding specialist species of Notiobia did not appear to do the reverse and seemed to avoid Melastomataceae fruit falls. The carabid assemblage at fig fruit falls was more diverse than the assemblage at those of Melastomataceae. Among the Melastomataceae, carabid species richness was highest at Miconia fruit falls and lowest at Loreya fruit falls. The three most common predatory species caught at Ficus fruit falls were also caught at those of Melastomataceae and appeared to reproduce at both fruit fall types. The proportion of the carabid assemblage accounted by predatory species was much lower at Melastomataceae (1.8%) than at fig fruit falls (8%).     

The reproductive biology of a riparian Mediterranean shrub, Nerium oleander L. (Apocynaceae)

This study presents data on the reproductive characteristics of Nerium oleander, an evergreen, sclerophyllous shrub inhabiting the banks of temporary streams in all countries around the Mediterranean seaboard. Two southern Spanish populations (El Garrobo and Grazalema) were selected to investigate flowering, dispersal and seed germination phenologies, together with morphological and functional traits of flowers, fruits and seeds. Observations on pollinator visitation, fruit set, and seedling survival were also carried out. Plants produce massive flower displays of showy, tubular flowers void of nectar that rely on insect cheating for pollination. Hand-pollinations and seed germination tests demonstrated full self-compatibility. Automatic selfing is prevented by spatial separation of stigma and anthers, and pollinators are thus necessary for reproduction. Low pollinator visitation rates are the rule, as indicated by the fact that observations spread over 2 years yielded only eight insect records. Percentage fruit set of open-pollinated flowers was found to be extremely low (0.1–4.9%), while hand-pollination increased fruiting levels to 34–50%. Direct and indirect evidence point to consistently pollen-limited reproduction in this species. If a large number of flowers within any inflorescence are pollinated artificially, however, resource limitations operate and pods from ovaries pollinated late in the season are aborted. On average, the maximum of ovaries developing into fruit within any inflorescence is 4. It is suggested that, in this nectarless species, about 80% of total are ‘excess’ flowers which contribute to increase pollinator attraction. Nerium oleander pollen is aggregated into a sticky substance, which allows the fertilization of many ovules after a single, probably rare, pollination event. Fruits are many seeded follicles (181 seeds per fruit on average), so that individual plants often liberate thousands of seeds in spite of the low percent fruit set. The hairy, water-dispersed seeds are released during the rainiest season in the year, and germination follows rapidly. All seedlings tracked died before completing 1 year of life, mostly because of desiccation during the first summer drought. Pollination by deceit in this Mediterranean species is discussed in terms of phylogenetic constraints within the mainly tropical family Apocynaceae.