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The family Cleomaceae is characterized by remarkable floral diversity and abundant nectar and pollen production. In this study, we evaluated the flower functional characteristics associated with the floral diversity of 10 Cleomaceae species, in addition to respectively seven and five accessions of Tarenaya hassleriana and T. longicarpa. The flowers were examined through five types of crosses and thus we determined the most efficient type of crossing based on the number of seeds. In addition, we evaluated pollen limitation, self-incompatibility, self-pollination and explored the possible effects on seed germination. The species can be grouped into three groups based on sexual systems: andromonoecious, hermaphroditism (chasmogamous and cleistogamous), and polygamomonoecious flowers. Gynandropsis gynandra, T. aculeata, T. diffusa, and T. microcarpa exhibited autogamy, whereas the other species did not. Overall, hand cross-pollination produced the highest seed yield, followed by open pollination. Self-pollination produced the lowest number of seeds, with no seed production noted in 16 accessions. Interestingly, the pollination type did not affect seed germination. Together, these results indicate the potential of the Cleomaceae family as a source of information regarding mechanisms involved in the determination of reproductive traits in plants.

Reproduction is key to determine the success of “winner” species. Plants that have an autogamous reproductive system to ensure their reproduction, but which maintain the possibility of cross-pollination, are the most flexible. Here, we aimed at understanding how those mechanisms occur in Sida cordifolia , an introduced pantropical weed. We recorded self-pollination mechanisms, monitored flower anthesis, and carried out a functional morphometric analysis. Based on those data, we established an experimental design of controlled pollination to measure the reproductive success generated by each self-pollination mechanism. We found two spontaneous self-pollination mechanisms: a prior one, during pre-anthesis, and a delayed one, at the moment of flower closure. However, partial dichogamy and herkogamy maintained during anthesis enabled cross-pollination. The floral attributes that maintain these mechanisms are fixed in the population. Alone, self-pollination mechanisms provide half of the fruit production, but together they are comparable to natural and cross-pollination with nearly total success. We show, for the first time, the interaction between prior and delayed self-pollination mechanisms and discuss how their combination enables autogamy but maintains the possibility of cross-pollination. The similar floral morphology of species of the pantropical genus Sida and the diversified self-pollination mechanisms in the family Malvaceae lead us to believe that this process may occur worldwide. Weedy species can be models for studies of floral biology, as they may have unique floral mechanisms that make them “winners” in the context of biotic homogenization.

Heterostyly is a polymorphism in which populations comprise two (distyly) or three (tristyly) floral morphs with reciprocal positioning of the height of the anthers and stigmas (reciprocal herkogamy). Such reciprocal herkogamy permits precise pollen placement on pollinators’ bodies and pollination success by promoting disassortative pollen transfer between floral morphs. Here, we aimed to understand how the different components of reciprocity relate to and differ from each other in distylous flowers, and whether factors, such as genus, morph-ratio variation, and corolla tube length influence the imprecisions in the sexual organs within populations. We gathered literature and original morphometrics data comprising 98 Palicourea and Psychotria populations from 44 species, the two largest distylous Rubiaceae genera, which differ in some floral features and pollination systems (hummingbirds vs. insects, respectively). We estimated reciprocity using new inaccuracy indices and standardization techniques, which allowed comparisons among a wide array of populations. Our results showed that maladaptive bias (i.e. departure from optimum reciprocity) of low organs was higher than the other decomposed inaccuracies indices tested. In addition, inaccuracy of low organs was higher than those of high organs. We did not find any relation of either genus, morph-ratio variation, or corolla tube length on general inaccuracy measurements. Apparently, pollinator-mediated selection on floral traits, imposed by different pollinators groups, did not differ markedly among the studied distylous Rubiaceae. This is the first study on inaccuracy components for such an ample array of populations and provides insights on the relative importance of morphological traits that optimize the functionality of distyly. We highlight the applicability of using standardized reciprocity indices for cross populational investigations, which may both support previous insights and reveal unknown patterns in distylous plants.

Galipeinae is the most diversified group of neotropical Rutaceae, presenting a wide floral diversity. However, the floral features in the species of the group have rarely been studied, hindering the understanding of functional aspects of particular floral attributes in relation to the biology. In this study, we investigate the floral biology and pollination of Angostura bracteata and Conchocarpus macrophyllus (Galipeinae), which are co-flowering and sympatric species occurring in the Atlantic forest of southeastern Brazil. Both species have tubular, nectar-rewarding, monosymmetric flowers, with two fertile stamens on the posterior side of the flower and five anterior staminodes. C. macrophyllus is most frequently pollinated by butterflies and less frequently pollinated by medium-sized bees. A. bracteata is also frequently pollinated by butterflies, shared, in part with C. macrophyllus, and less frequently pollinated by settling moths and by hummingbirds. Since we found that butterflies transfer the pollen grains of C. macrophyllus and A. bracteata through different body parts, it is unlikely that interspecific pollen mixture occurs, despite pollinator sharing. Although functionally generalized, most floral features indicate specialization for pollination by lepidopterans in both species. So, the related floral attributes consist of a long and narrow floral tube, as well as delicate landing platforms, and nectaries that produce minute quantities of dilute nectar, among others. Functional staminodes presenting pollen secondarily in the ventral region of the flower in A. bracteata are herein reported for the first time for Rutaceae, which results in a wider spatial presentation of pollen and may also increase the accuracy of sternotribic pollination. In C. macrophyllus, the staminodes bear pollen-collecting hairs, which may avoid spontaneous self-pollination or serve to scrape pollen from the tongues of pollinators. Our results indicate that the function of staminodes in the biology of the species may have influenced their maintenance throughout the floral evolution of Galipeinae.

Zygophyllum fabago is a species within the arid-adapted family Zygophyllaceae. The species is characterized by the co-occurrence of dichogamy and herkogamy. In order to understand the effect of these two complementary anti-selfing mechanisms in reproductive success, we conducted a detailed study of floral biology in Z. fabago. Our results indicated an incomplete separation of the female and male phases which is referred to as partial dichogamy. We found two floral morphs with distinct stigma position: the Central-morph (C-morph) and the Lateral-morph (L-morph). The stigma-stamen distance in the L-morph was significantly larger than in the C-morph in early, mid, and late male stages indicating a high degree of herkogamy. The amount of pollen load of the L-morph stigma under control and selfing condition was significantly lower than of the C-morph, whereas we found no significance difference of pollen load between C and L-morphs under outcrossing condition. Partial protogyny provided opportunities for delayed selfing. On the other hand, the evolution of lateral herkogamy provided an effective mechanism to regulate the degree of delayed selfing in accordance with the outcrossing possibilities in the environment. A combination of dichogamy and herkogamy, therefore, contribute to reproductive success of the species in unpredictable desert environment.

Distylous species possess two floral morphs: S-morph with short styles and long stamens, and L-morph with long styles and short stamens. The reciprocal positioning of anthers and stigmas is hypothesized to promote legitimate (between-morph) pollination. Deviations from reciprocity can negatively affect legitimate pollen deposition. The functioning of reciprocal herkogamy occurs if pollinators collect pollen of the L- and S-morph on different parts of the body, and then contact the stigmas of the opposite morph. However, few studies provide experimental evidence that the pollen deposition from the two morphs is stratified on the pollinator's body, especially for hummingbirds. We studied three populations of Palicourea rigida Kunth, an abundant shrub of the Neotropical savanna, to test the function of distyly as a mechanism to promote the differential placement of pollen on different parts of the pollinator's body and facilitate legitimate pollination. For this, we quantified high and low organs reciprocity, pollen dimorphism and pollen flow and developed a method for simulating floral visits by hummingbirds (main pollinators) to test whether pollen deposition occurs in a stratified manner on the bill. We found greater reciprocity in low organs, which explains the greater legitimate pollen deposition on S than L stigmas in two populations. In the other population, there was no difference in legitimate pollen deposition between morphs. Our findings corroborate the evolutionary models which have proposed that distyly promotes pollen deposition on specific parts of the pollinator's body. Pollen from S anthers was more deposited at the base of the bill, while pollen from L anthers appeared on the middle section of the bill. This stratified pollen deposition on the hummingbird's bill corresponded to the anther height of the pollen-donor morph and stigma height of the opposite morph, facilitating the reception of legitimate pollen, thus demonstrating the ecological functioning of distyly.

Reproductive biology in the highly diverse Cactaceae family is described in only few species. Given that a large number of species are rare, threatened, or endangered, and the entire family is included in Appendix II of CITES, the limited knowledge about their reproductive biology is of major concern. Mammillaria pectinifera is an endangered, small, globose cactus endemic to the Tehuacan-Cuicatlan region in Central Mexico. We aimed to characterize some basic aspects of its reproductive biology in three populations. We described flower morphology and anthesis, identified floral visitors, and evaluated the occurrence of spontaneous self-fertilization and the success of open pollination. Diurnal anthesis in flowers lasted about 4 h/day and almost all flowers lasted only one day after opening. The analyses of variance revealed differences in flower morphology among populations. Herkogamy was positive and significantly different among populations. Field experiments revealed that open-pollinated flowers were highly successful in setting fruits and seeds. These results corroborate those reported in other Mammillaria species. Autonomous self-pollination was negligible and ineffective. Bees of the genus Ceratina were dominant among the captured flower visitors, and estimations of their maximum foraging distance indicated successful outcrossing in plants. This study indicates almost complete dependency of M. pectinifera on pollinators for fruits and seeds production. Our results serve as a basis for future research on reproductive biology of M. pectinifera and other rare and endangered cacti.

The anatomy and morphology of a representative each of the genera Chaetolepis and Monochaetum were studied from Costa Rica. Both species showed adaptations for inhabiting high elevations, especially Chaetolepis cufodontisii , which is the only representative of this mainly Andean genus in Central America and is restricted to the paramos of Costa Rica. The latter has amphistomatic, ericoid leaves with unusual glands on the adaxial leaf surface, stomatal crypts and glands in the abaxial surface, stomata on the anther walls, and a double lining of druses in the hypanthium. In the case of Monochaetum amabile , the leaves have a hypodermis and lack stomata on the adaxial leaf surface as well as conspicuous glands or stomatal crypts, and the hypanthium has a single, sparser lining of druses. A comparison between the leaves of each of the species in this study with species previously studied form South America shows that the Costa Rican representatives of each of these genera show more significant anatomical and morphological modifications for living at high elevation than their South American counterparts. A type of herkogamy that involves the style bent in opposite direction of the stamens is here confirmed in Chaetolepis cufodontisii . This type of herkogamy is shared with other species of Chaetholepis as well as its closest relatives that occur at the highest elevations in the Andes, Busquetia and Castratella . Some species in other more distantly related genera at elevations as low as sea level such as some Blakea also show this type of herkogamy suggesting this floral type is associated to pollinators regardless of the elevation the plants inhabit.

Grewia asiatica L., an Asian shrub, is indigenous to India. Despite its immense importance in the Ayurvedic and traditional systems of medicine scientific and commercial exploration has been neglected. In this direction, we undertook systematic studies to understand the sexual system, breeding behaviour and reproductive phenology deployed by the species. Our results suggest that the species practices mixed mating as a consequence of temporal dichogamy of protandrous type and herkogamy with stigma slightly above stamens. Sequential floral evocation in acropetal order and profuse visitation by pollinators predispose G. asiatica to receive cross pollen. In a situation of non-receipt of pollen through insect pollinators, self-fertilization is prevalent by recurvation of receptive stigma towards dehiscent anthers. Seed set efficiency and fruit maturation are independent of pollen genotype (self/cross). Pre-emergent reproductive success (PERS), a measure of number of viable seeds that enter the ambient environment, was around 21%, which is indicative of moderate reproductive success. A self-compatibility index (SCI) and self-fertility index (SFI) showed values of 0.66 and 0.55, respectively, indicating the self-fertile and self-compatible nature of G. asiatica. The present study provides a detailed exposition of various reproductive features and breeding system prevalent in G. asiatica. These aspects are fundamental to understand the efficiency or failure of a species for genetic variation, crop improvement and evolutionary success.

Marantaceae are a pantropically distributed family of perennial herbs and lianas in the understory of tropical rainforests. They are characterized by a unique pollen transfer mechanism. To understand its functional significance and evolution, field investigations have been conducted in Gabon. Data from 28 (of 35) species from Central Africa are achieved. The pollen–ovule ratio (34–140:1; exception Sarcophrynium 2.5:1) falls into the range of facultative autogamous species. All investigated species were proven to be self-compatible; however, only two were autogamous. Natural fruit set was generally low (10.9 ± 10%). The highest natural fruit set was found in Marantochloa purpurea (29.7%), Ma. grandiflora (33.5%) and the two autogamous species Halopegia azurea (31%) and Marantochloa leucantha (35%). Considerable higher fruit set could be reached in all species by hand-self-pollination. We conclude that autogamy is generally avoided through herkogamy based on secondary pollen presentation on the back of the style head – a central component of the specific pollen transfer mechanism. However, with respect to the consecutive visit of pollinators to several flowers of the same individual geitonogamy cannot be excluded. The aggregated pollen transfer via the explosive pollination mechanism might be interpreted as an adaptation to low pollinator visitation rate, pollen limitation might explain the low fruit set.

Protogyny is supposed to represent the ancestral form of dichogamy in the angiosperms, but is rare in advanced groups such as the Asteridae, in which protandry prevails by far. Here we report on an unusual form of protogyny combined with herkogamy in a Chinese species of Gesneriaceae (Asteridae–Lamiales): Oreocharis acaulis (formerly Opithandra acaulis). This is characterized by a conspicuous protrusion of the style from the flower bud and the stigma becoming receptive before corolla opening (female-only stage; preanthetic protogyny) and both sexes staying functional during anthesis (hermaphroditic stage), with the stigma presented above the anther level (approach herkogamy). The plants studied were found to be self-compatible, but autonomous self-pollination and apomixis were not observed. Successful pollination was found to depend fully on the presence of insect pollinators (Bombus sp.). The visiting frequency was higher in the hermaphroditic stage (in which also more nectar was produced) than in the female-only stage. The out-crossed flower buds opened earlier and had a shorter flowering period than selfed flowers. Similarly, the outcross-pollen germinated earlier and the pollen tube growth was faster than in self-pollen. Anthers, pistil and corolla of O. acaulis obviously form an integrative functional unit in which the elongated style plays a key role both in pollen-dispensing and pollen-deposition. The combination of preanthetic protogyny with herkogamy has probably arisen through selection for promoting out-crossing and prolonging the exposition time of the receptive stigma in order to capture a higher amount of pollen grains. This may be understood as a strategy to cope with scarcity of pollinators in the plants’ habitat.

Variation in style length and anther–stigma distance (ASD) was investigated in 18 populations of Ixiolirion songaricum, an early-spring ephemeral perennial herb in northern Xinjiang. The effect of ASD on autonomous self-pollen deposition and seed set was assessed using bagging experiments. Seed production under autonomous self-pollination, cross-pollination and natural pollination was determined by manual pollination experiments. Stigmas of multiple flowers within an individual were sandwiched between two separate anther levels, and no individuals possessed approach or reverse herkogamy. Style length varied continuously among flowers, resulting in a wide range of variation in ASD. There were fewer flowers with a small ASD than with a large ASD in populations. ASD was negatively correlated with autonomous self-pollen deposition and seed set, but it was positively correlated with natural pollination seed set. Seed production under natural pollination was higher than that under autonomous self-pollination, but it was smaller than that under cross-pollination. Variation in style length and ASD among flowers was not caused by style or stamen elongation in I. songaricum, which differ from other species reported in literature that have continuous variation in style length and ASD.

Currently, pollination is seen as involving more generalist interactions than specialized ones. Supporting this trend, some nocturnal distylous flowers may also receive floral visitors during the day, and since the latter contribute to fruit set, the pollination system is mixed and less specialized. Common among the Rubiaceae, distyly has been regarded as a reproductive strategy which requires a precise and specialized pollination system, and in this important tropical family, environmental disturbance and pollination failure have been used to explain anomalies in distylous features. Faramea cyanea Mull. Arg. is a common tree species in forest formations in the increasingly threatened Cerrado biome, the Neotropical savannas in Central Brazil. We evaluated the floral morphology, pollination biology and breeding system of a population of F. cyanea. Despite their moth pollination features, flowers were visited by diurnal (bees) as well as nocturnal (moths) pollinators. Experimental results showed that both pollinator groups contributed equally to pollen flow and legitimate pollination. The population presented distyly, isoplethy and heteromorphic self-incompatibility. Although F. cyanea did not present exact reciprocal herkogamy between floral morphs, pollination and reproductive success were not impaired. Floral features, which allowed pollination by complementary groups of pollinators, may explain the absence of anomalies in the isoplethy and distylous features in the studied population, anomalies which have been observed in other sympatric distylous Rubiaceae.

Plants with hermaphrodite flowers risk conflict between male and female sexual function due to close proximity of sexual organs. Heterostyly, a genetic floral polymorphism characterized mainly by reciprocal herkogamy, may reduce this sexual conflict by increasing the precision of pollen transfer between morphs. This sexual organ reciprocity is often associated with various ancillary characters and a heteromorphic incompatibility system. Here we describe the morphometrics associated with heterostyly and ancillary characters in Plumbago auriculata. Using controlled pollination experiments, we show that this species has a heteromorphic incompatibility system. We also document the fauna of long-proboscid fly and butterfly pollinators in a P. auriculata population in KwaZulu-Natal, South Africa. © 2009 SAAB. Published by Elsevier B.V. All rights reserved.

Herkogamy may act as a mechanism to reduce interference between the reproductive functions of female and male organs, but too great a distance between stigmas and anthers may also decrease the outcross pollen transfer and male and female fitness. Our goal was to quantify the effect of movement herkogamy in Kosteletzkya virginica on reproductive success and its contribution to pollen receipt and reproductive assurance. Field investigations and hand-pollination experiments were performed to test: (1) the relationship between herkogamy before curvature of un-pollinated lobes and reproductive success under pollinator exclusion; (2) the contribution of movement herkogamy to pollen receipt; and (3) the relationship between pollen load and seed set. We noted that variation in herkogamy before curvature of un-pollinated lobes did not affect the outcome of autogamous self-pollination measured by fruit set and mean number of seeds per fruit. Under natural conditions, 39% of pollen grains deposited per flower were from autogamous self-pollination via movement herkogamy resulting in contact between anthers and stigmas. The relationship between the amount of pollen grains and the number of seeds per capsule was highly significant. Flowers producing four or five seeds received more pollen grains than those producing only one seed. Our data provides experimental evidence that movement herkogamy, which decreases the separation between anthers and stigmas and results in delayed self-pollination, contributes to pollen receipt and further enhances seed set when pollinators are scarce or absent.

The floral biology of Aristolochia argentina (Aristolochiaceae) was studied in natural populations in Cordoba, Argentina. This native vine has flowers that attract mainly scuttle fly pollinators of the genus Megaselia (Phoridae). The trap-like perianth is formed by a limb, a tube, and a basal utricle. The limb produces an odor that recalls decaying plant tissues, which apparently mimics the natural oviposition substrate of the flies. The insects stay entrapped inside the utricle for approximately 24 h, making contact with the sexual organs of the flower. When released, they can become captured again in other flowers. The mechanisms of herkogamy and protogyny are efficient. Although self-compatibility exists, as demonstrated by the high percentage of fruits produced by geitonogamy, fruits were not produced under natural or artificial autogamous conditions. Natural pollination showed significantly lower fruit set than xenogamous and geitonogamous crosses.

In spite of their tiny dimensions (3×5 mm2), the strongly honey-scented flowers of Guazuma ulmifolia (Malvaceae–Byttnerioideae) provide six sexual chambers. A central female unit is surrounded by five interconnected male compartments. At the onset of anthesis the strap-shaped odoriferous petal appendages form an open star with the female chamber in the centre. Hereafter, they wilt, intermingle and finally lock access to the stigma. Meanwhile, wilting sepals liberate new entrances from the back between the petal claws. They give way to nectar-offering male chambers. In each of them a well-lit (but closed) window lures the visitor into a standard position for passive pollen uptake. Finally, the insects have to back out of one of the rear entrances. It remains unknown how the minute visitors (maximum height ca. 0.5 mm) – if ever – overcome the distance to another Guazuma tree.

The combined occurrence of both herkogamy and dichogamy in a hermaphrodite species has been considered to strongly favour outcrossing. In this study, we investigated in detail the reproductive ecology of Gentiana straminea Maxim. (Gentianaceae), a hermaphrodite perennial endemic to the Qinghai-Tibet Plateau. In a series of observations and experiments over four consecutive years, we examined whether the combination of dichogamy and herkogamy in individual flowers completely prevents geitonogamous pollen transfer in this species. The mode of floral development clearly indicates that autonomous self-pollination is completely avoided through herkogamy and dichogamy in individual flowers. This implication was confirmed by the breeding experiments, since no seed was produced when flowers were isolated. However, this gentian proved to be highly self-compatible when geitonogamous selfing was artificially induced. Many flowers opened simultaneously on individual plants, the ratio of male to female phase flowers was close to 2:1 in each inflorescence, at the full anthesis phase, and they were randomly distributed amongst the upper, middle and lower parts of each stem's inflorescence. On average, Bombus sushikini Skorikov, the most frequent visitor and only legitimate pollinator of G. straminea, visited nearly two flowers per inflorescence, and four flowers per plant. Among the pollinators' foraging bouts, the proportions of geitonogamous visits to inflorescences or flowers within an individual plant were 29% and 37%, respectively. Therefore, despite the strict dichogamous and herkogamous characteristics of the individual flowers, geitonogamous selfing might still prevail in G. straininea because of the size of its floral displays and the continuous visiting behavior of B. sushkini. (C) 2005 Elsevier SAS. All rights reserved.

Sexual system, temporal variation in sex expression, and herkogamy were evaluated in 210 plant species in the Venezuelan Central Plain (VCP). This analysis was conducted considering the life forms, habitats, flowering time, pollination systems, and dispersal syndromes of the plant species. Hermaphrodite species dominated the community (75.2%; N = 158 ), followed by monoecious taxa (17.1%; N = 36 ), and then dioecious (7.6; N = 16 ). Most species were adichogamous (=homogamous) (75.2%; N = 155 ), followed by protandrous (16.5%; N = 34 ), and protogynous (8.3%; N = 17 ). The frequency of herkogamous species was higher ( N = 124 ; 60.2%) than the non-herkogamous ( N = 82 ; 39.8%). The three reproductive traits interacted significantly in a way that complements their effectiveness in promoting cross-pollination and avoidance of pollen–stigma interference: hermaphrodite-adichogamous species occurred in similar frequency to herkogamous and non-herkogamous species; monoecious-adichogamous species were mostly herkogamous, and all hermaphrodite, functionally dioecious-adichogamous, species were herkogamous. Sexual system, herkogamy, and dichogamy are associated with habitats in the savanna-forest mosaic of the VCP. The proportion of dioecious species decreased from trees to annual herbs and from forest to disturbed areas. Dichogamous species were most frequent for herbaceous plants, and non-herkogamous species dominated in annual herbs. The frequency of herkogamous species decreased from forest to disturbed areas. Sexual system was significantly associated with pollination system. Most dioecious and monoecious species had generalist pollination. A three-factor log linear analysis indicated that for any combination significantly. Sexual systems and herkogamy were associated with the respective seed dispersal syndrome. Most dioecious and herkogamous species were dispersed by frugivores, while monoecious plants tended to be dispersed by granivores and wind. Flowering time of dioecious species peaked during the dry–rainy transition period, whereas that of monoecious species was greatest during the rainy season. Therefore, specific biotic and abiotic conditions may enforce the occurrence of unisexuality in the community. In a similar way, dichogamous species tend to flower during the rainy season, associated with herbaceous life form and wind pollination. These results are discussed in the context of evolutionary and ecological trends.

Summary We investigated the occurrence of herkogamy and dichogamy in 43 populations of the grassland biennial Gentianella campestris in Sweden, and experimentally tested their significance for the reproductive system of the species. Furthermore, we performed a heritability test to evaluate the potential for selection on traits related to herkogamy. Dichogamy did not occur in the studied populations, and herkogamy was restricted to five populations. Two types of herkogamy were found, one with the stigma protruding above the anthers (hyper-stigmatic), and one with the stigma positioned below the anthers (hypo-stigmatic). In both types, the stamens elongated during anthesis. In the hyper-stigmatic plants, the anthers reached and pollinated the stigma after c. 34 days. This did not occur in hypo-stigmatic plants. Pollination experiments showed that the plants were self-compatible and that elongation of stamens provided a mechanism for reproductive assurance in hyper-stigmatic plants. The type of herkogamy did not differ between flowers of the same developmental stage within a plant. In two of the five herkogamous populations, the herkogamy differed between plants, but there was a normal distribution of the anther-stigma separation. Herkogamy was not related to population size. A comparison of the anther-stigma separation of self-pollinated mother plants and their offspring showed that herkogamy was a highly heritable trait (average h 2 = 0.85), that clearly has the potential to respond to selection

Summary Mussaendopsis, an arborescent Southeast Asiatic genus of two species (M. beccariana: from the Malay Peninsula and Sumatra East to Borneo; M. celebica: endemic to Sulawesi) has mature stipules in an intrapetiolar position. Developmental studies on M. beccariana, however, showed that they are initially interpetiolar. The large coriaceous leaves, characterized by the presence of two hypodermis layers, have conspicuous sclerenchymatic bundle sheath extensions. The optical attractiveness of the (pleio-)thyrsic or thyrsopaniculate, axillary inflorescences is markedly increased by the presence of enlarged, petaloid, show calyx lobes which are produced only by certain flowers of an inflorescence (± pseudanthium-like). The corollas (corolla lobe aestivation contorted to the right in bud) differ significantly in the two species: In M. celebica, they are hypocrateriform (corolla tubes c. 3.5 mm long; tubes always shorter than the lobes) and in M. beccariana, they are rotate (tube subobsolete to obsolete). The latter, suspected to be myophilous (“dishblossom”, large, exposed ± flat disk profusely producing nectar), shows dichogamy (protandry) coupled with herkogamy. The ovary of the bicarpellate gynoecium contains two large placentas, each with numerous hemianatropous, tenuinucellate and unitegmic ovules which are produced in a sequential fashion. In the course of flower and fruit development, ovules and developing seeds undergo a drastic change in shape: ovules soon develop a winglike extension (marked elongation of the chalazal region!), resulting in a distinctly imbricate arrangement of the tightly packed, variably shaped ovules. Further on, the wing-like outgrowths also encompass the micropylar end of the ovules so that, finally, the mature seeds show an elongated, bipolar wing which surrounds the ± centrally located endosperm- and embryo-bearing part on all sides. The exotesta cells have conspicuous anastomosing local secondary thickenings on the inner tangential walls only. The distinctly oily endosperm consists only of a few cell layers surrounding the relatively large embryo. The fruits are septicidal capsules with hard walls (thick, sclerenchymatic endocarp). The pollen of M. beccariana, 3-colporate and ± spheroidal (P = ± E = 18 – 19.8 μm), has a reticulate to finely reticulate exine. The presented data do not seem to seriously contradict the recently suggested placement of Mussaendopsis in the tribe Coptosapelteae, although they might suggest a ± isolated position of the genus in this essentially paleo tropical tribe.