Pollination of Bactris (Palmae) in an Amazon forest

Phenology, inflorescence behavior, and pollination of 10 sympatric taxa ofBactris were studied in a lowland Amazon forest. Taxa flowered over an eight month period during the rainy season and early dry season, but individual taxa flowered for one to a few months. Related taxa had mostly non-overlapping flowering periods. Inflorescence behavior was similar for all taxa, with nocturnal pistillate anthesis and temperature elevation, followed 24 hours later by rapid, nocturnal staminate anthesis. Pollinators of all taxa were small weevilsPhyllotrox (Curculionidae) and nitidulidsColopterus (Nitidulidae), although various other insect visitors were recorded. Large numbers ofPhyllotrox were recorded on inflorescences, but weevil sex ratios were highly skewed.     

Comparison between the allergenic airborne pollen in Trieste and at Lozzo di Cadore (Italy) in 1989

Summary A comparative study was carried out between aeroallergenic pollen spectra in Trieste and at Lozzo di Cadore. The two localities were found to be different on a five-day running mean basis as to the 8 pollen taxa monitored by the National Aerobiological Monitoring Network managed by the Italian Association of Aerobiology (AIA). In the zone of Lozzo the pollination curve of the spring flowering taxa showed a lag of about one month due to the colder climate. Lozzo di Cadore showed a poor airborne pollen content,Corylus and Graminaceae being prevailing. Trieste has a higher airborne pollen diversity and longer pollination times because of its higher floristic and vegetational complexity. In Trieste the allergenic pollen spectrum showed great quantities ofOstrya, Quercus, Oleaceae, Graminaceae and of ruderal taxa, widespread over the area, due to man's influence.     

Pollination by hummingbirds and bees in eight syntopic species and a putative hybrid of Ericaceae in Southeastern Brazil

We report on flowering phenology, floral morphology, pollinators, and nectar for eight species and a putative natural hybrid belonging to Agarista, Gaultheria and Gaylussacia that occur syntopically in a montane area. The campanulate to tubular flowers of eight out of nine Ericaceae taxa are primarily pollinated by either hummingbirds or bees. Flowering overlaps in all species but slight differences of floral shape, colour, and nectar characterize pollination by each pollinator group. Differences in floral traits are not large enough to exclude secondary pollinators. Thus, either the main pollinators of a species belonging to its syndrome, or secondary pollinators of a species belonging to different syndromes, may allow for inter-specific crosses.     

Self-compatibility in distylousHedyotis salzmannii (Rubiaceae)

Hedyotis salzmannii (Rubiaceae) is distylous. Experimental pollination revealed that both morphs are self-compatible. However, the thrum morph proved to be more self-compatible. Hand cross-pollination between different plants of the same floral form produced less seed-sets per pollination than hand cross-pollination between pin and thrum or thrum and pin pollination. Two species ofHymenoptera, oneApidae and oneHalictidae, and two species ofDiptera (Syrphidae) were observed as pollinators.     

Pollination ofOpuntia lindheimeri and related species

The large, yellow, bowl-shaped flowers ofOpuntia lindheimeri, O. discata, O. phaeacantha major, andO. compressa in Texas are visited by various species of beetles and bees. The beetles and small bees (Perdita, Dialictus) are pollen thieves. The pollinators are the medium-sized and larger bees (Melissodes, Diadasia, Lithurge, Megachile, Agapostemon, etc.). Different species of theOpuntia lindheimeri group have the same pollination system and there is no evidence of any floral isolation between them. The pollination system of these species ofOpuntia in Texas is essentially the same as that ofEchinocereus fasciculatus andFerocactus wislizeni in Arizona.Pollination of North American Cacti, II.—SeeGrant & Grant (1979).     

Pollination ofOpunta basilaris andO. littoralis

The flowers ofOpuntia basilaris andO. littoralis in southern California are visited commonly by beetles(Carpophilus, Trichochrous) and bees (especially anthophorids, megachilids, and halictids), but are pollinated mainly by the bees. This agrees with observations presented in the previous papers in this series for other cactus species in Arizona and Texas. The available evidence indicates that the large, diurnal, cup-shaped flowers in cacti of the American Southwest are primarily bee-pollinated. Our earlier view that theseOpuntia flowers are also pollinated to a significant extent bynitidulid andmelyrid beetles must be modified now in the light of further evidence. Some pollination probably is carried out by small beetles, but it probably represents only a small proportion of the total pollination.Pollination of North American Cacti, III.—See alsoGrant & Grant (1979) andGrant & al. (1979).     

Floral scent chemistry and pollination ecology in phytelephantoid palms (Arecaceae)

The subfamilyPhytelephantoideae comprises three genera (Ammandra, Aphandra, andPhytelephas) and seven species of dioecious palms. The floral scents ofAmmandra dasyneura, A. decasperma, Aphandra natalia, Phytelephas aequatorialis, P. macrocarpa, andP. seemannii were analyzed by gas chromatography-mass spectrometry. We studied the pollination biology ofA. natalia, P. aequatorialis, andP. macrocarpa, and tested how the synthetically produced main constituents of the floral scents ofAphandra andPhytelephas attracted insects in two natural populations ofPhytelephas. The genera are distinct in terms of floral scents.Ammandra has sesquiterpenes,Aphandra (+)-2-methoxy-3-sec-butylpyrazine, andPhytelephas p-methyl anisol. These constituents dominated the scents quantitatively and qualitatively. The similarity between scents of male and female inflorescences was 76.5% inAmmandra, 84.2% inAphandra, and >99% inPhytelephas. Different species ofAleocharinae (Staphylinidae) pollinateAphandra natalia andPhytelephas species and reproduce in their male inflorescences.Derelomini (Curculinoidae) andMystrops (Nitidulidae) only visit and pollinatePhytelephas in which male inflorescences they reproduce. A species ofBaridinae (Curculionidae) only visits and pollinatesAphandra natalia, and reproduces in its female inflorescence. The apparent reliance on one or a few floral scent constituents as attractants and few and specific pollinators may indicate co-evolution. Sympatric species ofPhytelephantoideae have different scents. We suggest that species with similar scents have allopatric distributions due to the absence of a pollinator isolation mechanism.     

Fig volatiles: Their role in attracting pollinators and maintaining pollinator specificity

Each fig tree species (Ficus) is totally dependent on a specific species of wasp for pollination and the larvae of these wasps only develop in the ovules of their specificFicus host. Because the fig crop on any particular tree is generally highly synchronized, the shortlived female wasps must leave their natal tree in order to find figs which are suitable for oviposition. Chemical volatiles produced by figs when they are ready for pollination are thought to be the means by which the wasps detect a suitable host. Gas chromatograms of the fig volatiles of 7 species ofFicus showed them to be species specific. Age related changes in the volatile profiles were noted as extra volatiles are produced when the figs were ready for pollination.     

Contrasting breeding systems in twoEriotheca (Bombacaceae) species of the Brazilian cerrados

The pollination biology and breeding systems ofEriotheca pubescens andE. gracilipes have been studied. These two species occur as trees in cerrado vegetation, the neotropical savannas of Central Brazil, with partially sympatric distributions. They have similar phenology and floral structure, although the flowers ofE. pubescens are larger. Both species have nectar flowers pollinated by largeAnthophoridae bees but the main pollinators of each species differ in size. The species have markedly different breeding systems: late-acting self-incompatibility inE. gracilipes and apomixis stimulated by pollination inE. pubescens.     

Floral mechanisms in the tribeSalpiglossidae (Solanaceae)

SinceDelpino (1869),Juel (1894, 1911), andMüller (inMöller 1921: 164), the flowers ofSolanaceae have received little attention with regard to function and pollination syndromes. The present paper deals with representatives of 6 of the 9 known salpiglossidean genera. Previous observations are updated and discussed at the tribal level. Most species studied are butterfly- or moth-pollinated. With the exception ofSalpiglossis, the fertile floral parts are concealed in the corolla tube, and their arrangement is specially suited for deposit of the pollen on the lepidopteran tongue. Particularly notable are (a) abundant stigmatic secretion that makes the pollen sticky, and (b) versatile anthers that optimize contact between the tongue and the thecae.Brunfelsia andBrowallia exhibit a mechanism analogous to that ofApocynaceae, however, with two entrances instead of five. When the tongue is inserted, it is forced to contact the stigma and becomes glued with its secretion. When the tongue is pulled out, it touches the anthers and causes slight balancing movement. InStreptosolen, very probably an ornithophilous descendant of theBrowallia stock, the mechanism is much simplified.Leptoglossis andHunzikeria bear a novel device for pollen deposition: there are two fertile wheel-like anthers that are capable of full rotation up to eight turns.     

北黄花菜的开花物候及传粉特性研究

北黄花菜是百合科萱草属的优秀观赏植物材料,也是进行品种创新的极有价值的野生种质资源。该研究对野生环境中北黄花菜的开花物候与传粉特性进行了连续三年的追踪观测,探讨其开花进程和传粉机制。结果表明:(1)北黄花菜种群的开花物候只有1个高峰期; 种群始花时间为5月末,盛花期为6月中旬,开花时间在30 d以上,单株花期为6～12 d; 开花同步性指数(S_i)分别为0.36、0.27和0.21,种群内个体开花时间重叠程度较低。(2)北黄花菜的开花数量与坐果数呈显著正相关(P<0.05),坐果数与单株花期长度呈极显著正相关(P<0.01),单株花期长度与始花时间呈显著负相关(P<0.05),表明北黄花菜开花数量越多,其坐果数越高。(3)北黄花菜的访花昆虫分属于4目10科共10种; 各访花昆虫的访花时间和行为区别较大; 主要的传粉昆虫有4种,其活动范围大,活动特点与北黄花菜午后开放的规律相匹配,能保证传粉效果; 部分访花昆虫虽然活动范围小,但可以帮助植物进行自花授粉; 两类访花昆虫的共同作用,使得北黄花菜的自然结实得到较大保障。上述结果可为北黄花菜的引种栽培和资源创新发挥实际作用。     

Alnus andBetula pollen content in the atmosphere of santiago de Compostela, North-Western Spain (1993–1995)

The present study analyzes the behaviour ofAlnus andBetula pollen in the atmosphere of the town of Santiago de Compostela (N.W. Spain) from January 1993 to December 1995. The main pollination period of both taxa is identified for each sampling year, which, in the case ofAlnus, took place in January and February and, forBetula, during April.Alnus andBetula pollen are found in very high quantities in the atmosphere of Santiago de Compostela, representing 5% and 12% respectively of the total annual pollen that was counted. We studied the correlation between pollen content each year for both taxa and the main meterological parameters (average, maximum and minimum temperatures, precipitation and hours of sunshine). Finally, we analyzed the diurnal behaviour model for each taxon. ForAlnus, the maximum concentrations were found around 20:00 h, while, in the case ofBetula, the main pollen concentration took place between 15:00 h and 20:00 h in 1993 and 1994, and at 00:00 h in 1995.     

Pollination ofNuphar (Nymphaeaceae) in Europe: Flies and bees rather thanDonacia beetles

Nuphar (Nymphaeaceae) comprises a small holarctic group of aquatic perennials whose flowers are pollinated by flies, bees, and beetles. We studied pollination in different populations of the two European speciesN. lutea andN. pumila in Norway and in Germany. Flowers are self-compatible and protogynous, preventing automatic selfing, and insect pollination is required for seed production. Sympatric populations were studied in Vest-Agder county in Norway to determine whetherN. lutea andN. pumila have the same or different pollinators. Allopatric populations ofN. lutea in Germany and Norway were then compared to determine whether their pollinator spectra differ as would be expected in an open flower with seemingly easily accessible pollen and nectar. Results of the present as well as previous studies of the pollination ofN. lutea andN. pumila show that both species are mainly pollinated by flies, including apparentNuphar specialists, such as the scatophagidHydromyza livens and the ephydridsHydrellia andNotiphila, the last also a long-known pollinator ofN. advena in Florida. Pollinator overlap between sympatric heterospecific populations was small, while allopatric conspecific populations had similar visitor and pollinator spectra. We found no evidence of pollination byDonacia beetles as reported from some North American populations ofNuphar. Dedicated to Univ.-Prof. DrF. Ehrendorfer on the occasion of his 70th birthday     

Comparative floral morphometrics in day-flowering, night-flowering and self-pollinated Caryophylloideae (Agrostemma, Dianthus, Saponaria, Silene, and Vaccaria)

Morphological variation of flowers with different pollination modes was studied in 53 species representing five genera (Agrostemma, Dianthus, Saponaria, Silene s.l., Vaccaria) of the subfamily Caryophylloideae. All species were classified a priori as either diurnal, nocturnal, or selfing. Canonical discriminant analysis (CDA) of 13 floral characters revealed significant correlations between floral morphometry and pollination modes. A CDA of taxonomical groups represented with more than three species (Dianthus, and subgroups of Silene s.l.: Lychnis, Silene s.str., and Viscaria), revealed that the discrimination between these four taxa, based on the same floral characters, is also well supported. Main factors for the discrimination of the species with different pollination modes were characters that (a) define nectar accessibility (calyx length, calyx tooth length), (b) are related to the positioning of anthers and stigmatic areas in relation to pollinators and (c) are important for the visual attractiveness of flowers (plate width). The functional distance between the nectar source (anthophore base) and contact zone with pollinators (style tips), given as the sum of anthophore length, ovary length, and style length (hence called AOS-complex) is better correlated with the calyx length than the single characters. Further, the total AOS-complex length differs significantly between pollination modes suggesting that these characters form a functionally linked complex that is related to the pollen placement on, and stigma contact with, the pollinator's body. However, the contribution of anthophore and style length to the total AOS-complex differed significantly between Silene s.l. and other taxa indicating that the taxonomic groups follow different evolutionary ways for the construction of the functionally linked AOS-complex.     

Pollination biology of annual and perennialLeonotis species (Lamiaceae)

The pollination syndromes ofLeonotis (Pers.)R. Br. are discussed. Ornithophily accounts for most of the nutlets set in perennialLeonotis species but in the annual species [L. nepetifolia (L.)R. Br.] autogamy prevails.Leonotis species are predominantly pollinated by a variety of sunbirds, although bees are also involved. Nectar is sucrose-dominant in perennial species but hexose-dominant in the annual.     

Pollination of sevenPlectranthus spp. (Lamiaceae) in southern Natal, South Africa

The genusPlectranthus (Lamiaceae) shows remarkable radiation on the sandstones of southern Natal and northern Transkei in South Africa, where six endemic species occur. Two of these endemic species,P. hilliardiae andP. oribiensis, are included in this study, as well asP. reflexus, for which only limited data are available. The other species that were studied areP. ambiguus, P. ciliatus, P. ecklonii, P. madagascariensis andP. zuluensis. Four of these taxa,P. ambiguus, P. hilliardiae, P. reflexus andP. saccatus var.longitubus, have uniquely long corolla-tubes (20–30mm) and this is related to pollination by nemestrinid flies of the genusStenobasipteron that have proboscides of similar length. Other nemestrinid species of the genusProsoeca have shorter proboscides and pollinate two species ofPlectranthus with shorter corolla-tube lengths (6–15mm). Acrocerid flies, tabanid flies and anthophorid bees are also important visitors to these species. This study on the pollination of seven species of varying corolla-tube lengths shows a correlation between floral tube length and proboscis length of insect visitors, many of which are recorded for the first time as pollinators ofPlectranthus.     

Plant reproductive interval and population density in aseasonal tropics

In some tropical areas, annual cycles in the environment and plant phenology are not clearly detectable. In such aseasonal tropics, it was found that plant population density is associated with flowering intervals within the same habitats and within the same pollination guilds, if some conditions are satisfied. This finding is based on observations of flowering phenology of butterfly-pollinated understory shrubs of the genus Ixora (Rubiaceae) for 36 months in a mixed dipterocarp forest in Sarawak, northwest Borneo. Plants did not receive sufficient pollination services and fruit set was pollination-limited. Under such conditions, it is theoretically predicted that the plant types that reproduce frequently would have higher population density than those that reproduce less frequently, because common types must avoid competition for pollinators and rare types can have a large floral display by storing resources during long reproductive intervals to attract pollinators efficiently. Observed relationships among plant reproductive intervals, pollinator attractions and population densities in Ixora are consistent with theoretical predictions. Based on the theory proposed in this paper, I discuss a factor promoting diversification of the genus Ixora and other taxa.     

Change of adaptations from entomophily to autogamy inParahebe linifolia (Scrophulariaceae)

Measurements of 16 inflorescence and floral characters from 5 populations ofParahebe linifolia (3 of entomophilous subsp.linifolia; 2 of autogamous subsp.brevistylis) were analysed. Discontinuous variation of three characters associated with the mechanisms of pollination suggests these are under strong selection towards different optima in each subspecies. Variation which is continuous and associated with the type of pollination in 4 characters mostly concerned with display is thought to result from selection for metabolic economies, counteracted strongly in subsp.linifolia, but less so in subsp.brevistylis, by selection for display. Nine more characters vary in a way not known to be associated with the two pollination systems.     

Notes on the pollination mechanisms ofMoraea inclinata andM. brevistyla (Iridaceae)

Individual flowers ofMoraea inclinata are nectariferous and last about six hours. They appear to be pollinated largely by bees in the familyHalictidae (Lasioglossum spp.,Nomia spp.,Zonalictus) and to a lesser extent by bees in the familyAnthophoridae (Amegilla). The mechanism of bee-pollination inM. inclinata is the Iris type; i.e., each flower consists of three pollination units (an outer tepal, a partly exserted anther, and the opposed style branch which terminates in a pair of petal-like crests). Bees rarely visit more than one pollination unit per flower. Transferral of pollen to the bee is passive and nototribic although all bees collected on the flowers were female and 55% of the bees carried pollen loads with 2–5 pollen taxa in their scopae.Moraea brevistyla flowers are nectariferous but lack scent and last two days. They are visited infrequently by bees and only one femaleLasioglossum spec. carried the pollen ofM. brevistyla. Unlike flowers ofM. inclinata those ofM. brevistyla deposit pollen only on the head and thorax. Bee-mediated autogamy in both species is avoided due to the erratic foraging patterns of the bees and the flexibility of each stigma lobe as the bee backs out of the flower. Approximately 2–4 flowers in the inflorescences of both species (6–8 flowers/infloresence) develop into capsules.     

Pollination of the southwestern Opuntias

This paper presents an overview of pollination systems inOpuntia sens. lat. in the southwestern United States. The floral syndrome of large, colorful, bowl-shaped, diurnal flowers is present in all of the prickly-pear species and most of the cholla (Cylindropuntia) species in this area. Pollination by medium-sized and large bees is established for some of the species with this floral syndrome and is predicted for the others. The same floral syndrome is widespread inOpuntia in other geographical areas.—Deviations from this floral syndrome occur in certain species of southwestern chollas, one of which has nocturnal disc-shaped flowers, and in several tropical American species groups or segregate genera with red hummingbird flowers. But such cases are relatively infrequent. Divergence between species with respect to floral syndrome and pollination system is not a common feature in the evolutionary pattern ofOpuntia. Pollination of North American Cacti, IV.—Previons parts of this series:Grant & Grant 1979a,Grant & al. 1979,Grant & Grant 1979b.