THE POLLINATION ECOLOGY OF ZENOBIA (ERICACEAE)

Zenobia is a shrub endemic to the coastal plain of the Carolinas and southeastern Virginia. The sole species, Zenobia pulverulenta, appears to be weakly self-compatible and partially self-pollinating. Fruit set was reduced, but not eliminated by excluding insect floral visitors. Insect visitors were collected and their pollen loads examined for Zenobia and foreign pollen. Analysis of these pollen loads and observations of insect-foraging behavior indicate that workers of three species of bumblebee (Bombus bimaculatus, B. griseocollis and B. impatiens) are. the principal pollinators of Zenobia. However, pollinator density and composition appear to be strongly influenced by the habitats in which Zenobia grows. Pollen and nectar serve as the primary rewards for pollinators.     

POLLINATION ECOLOGY OF PYRRHOPAPPUS CAROLINIANUS (COMPOSITAE)

Pyrrhopappus carolinianus and Hemihalictus lustrans constitute a mutualistic association: the early morning flowering of Pyrrhopappus provides the matinal bee with a nearly exclusive pollen source, although other plants must be visited for nectar. Female Hemihalictus, the primary pollen vector, tear open the anthers and remove the pollen before it is available to other bees. The foraging behavior of the bee insures cross-pollination. The flight pattern of the bees generally restricts the pollen dispersal range. If cross-pollination fails, then autogamy results from twisting of the styles that brings the stigmas in contact with the pollen presented on the styles of other florets. Schinia mitis is an important predator of the capitulae of P. carolinianus.     

THE POLLINATION ECOLOGY OF AQUILEGIA ELEGANTULA AND A. CAERULEA (RANUNCULACEAE) IN COLORADO

Aquilegia elegantula Greene and A. caerulea James occur in montane and subalpine habitats in the southern Rocky Mountains of western North America. The red and yellow flowers of A. elegantula are nodding, odorless, protogynous, and secrete a concentrated (44%) sucrose nectar in the floral spurs. Seed set in flowers under pollinator exclosures was 12% while seed set in open-pollinated flowers was 65%. The flowers of A. elegantula are pollinated primarily by the Broad-tailed Hummingbird (Selasphorus platycercus [Swainson]) and by at least three species of pollen-foraging bumblebees, of which Bombus occidentalis Greene is the most common. The blue and white flowers of A. caerulea are erect, mildly fragrant, protandrous, and secrete a 26% sucrose nectar. Seed set in caged flowers in the field averaged 39%. in uncaged flowers 54%. The most important pollinators of A. caerulea are the crepuscular hawkmoth, Hyles (=Celerio) lineata (Fabricius) and ten species of pollen-foraging Bombus. The most abundant bumblebee species, B. occidentalis, is also a frequent nectar thief. Differences in pollination systems alone probably do not constitute an effective anti-hydridization mechanism between A. elegantula and A. caerulea, but do serve to reinforce differences in habitat and flowering time that distinguish the two species.     

THE POLLINATION ECOLOGY OF SOLANUM ROSTRATUM (SOLANACEAE)

The pollination mechanisms and pollen vectors of Solarium rostratum have been examined by greenhouse experiments and field studies. Although the capacity for autogamy exists in this weedy annual, it rarely occurs because of two factors: (1) the morphology of the flower and (2) the foraging behavior of the various species of Bombus, the primary pollen vector in the regions studied. The percentages of geitonogamy and xenogamy are dependent on the flight pattern of the bees and the number of open flowers on a plant.     

THE POLLINATION ECOLOGY OF DELPHINIUM TRICORNE (RANUNCUL ACEAE)

The pollination ecology of Delphinium tricorne, a spring-ephemeral herb of eastern deciduous forests, was studied at eight sites in the Ohio River basin from West Virginia to southern Illinois. The plant was found to be obligately dependent for its pollination on queen bumblebees (Bombus Latr. spp.) and hummingbirds, to which the flowers are closely adapted in form, color, function, and blooming phenology. Other bees, including Anthophora ursina, Osmia bucephala, Ptilothrix bombiformis, and Xylocopa virginica; Lepidoptera, including Amphion nessus, Danaus plexippus, Epargyreus clams, Erynnis juvenalis, Hemaris thysbe, Papilio glaucus, P. philenor, P. troilus, Poanes zabulon, Vanessa atalanta, and V. cardui; and the beefly Bombylius major foraged for nectar and/or pollen on the flowers without pollinating them. Techniques employed in the study included insect exclosures to test fertility of plants in the absence of pollinators, analysis of floral colors by reflectance spectrophotometry and ultraviolet photography, analysis of pollinator behavior by cinematography and close-range stereophotography, collection and identification of visitors to flowers, and identification of pollen types carried by foragers on the flowers.     

POLLINATION ECOLOGY OF VACCINIUM STAMINEUM (ERICACEAE: VACCINIOIDEAE)

Successful fruit set by deerberry, Vaccinium stamineum (Ericaceae: Vaccinioideae) requires floral visitation by insects, and in particular by bees that collect its pollen by sonication of anthers (“buzz-pollination”). A diversity of bees visit deerberry flowers, but most species are either 1) infrequent, 2) polylectic (broad host range for pollen), or 3) principally nectar-seeking, and so are unimportant as pollen vectors. Both sexes of the solitary, oligolectic bee Melitta americana⁵ (Melittidae) are abundant at flowering deerberry bushes in central New York State. Female M. americana sonicate the deerberry anthers while imbibing nectar, and carry virtually pure scopal loads of deerberry pollen, unlike the other common visitor, Xylocopa virginica (Anthophoridae). Comparative analyses of bee 1) abundances, 2) buzz-pollination behaviors, 3) pollen fidelities, and 4) pollination efficiencies, all indicate that Melitta americana is the primary pollinator of Vaccinium stamineum.     

POLLINATION AND POLLEN ENERGETICS IN MEDITERRANEAN ECOSYSTEMS

Most plants in Mediterranean ecosystems are insect pollinated, with pollen being the main reward to pollinators. The great majority of pollinators (70%) are bees and flies. We measured the energy content of pollen from 40 plant species in these ecosystems that represent abiotic and biotic pollination modes as well as the number of species of their pollinators. Pollen energy content correlates with pollinator diversity. Pollen of wind-pollinated plants contained less energy than that of insect-pollinated plants; there was no difference between insect-pollinated dicots and insect-pollinated monocots. The median date of flowering (from 1 January) estimated for each of the plant species did not vary significantly either with the number of pollinator species or with the energy content of pollen. The reasons for the differing values of pollen energy content are discussed; in particular, its relation to the type of pollen reserves, length of the flower style, and pollination enhancement.     

SYNDROME‐DRIVEN DIVERSIFICATION IN A MEDITERRANEAN ECOSYSTEM

Phylogenetic methods to detect lineage diversification have been traditionally used within a particular taxonomic clade, but rarely applied to detect local diversification. For understanding in situ diversification triggered by novel conditions it is necessary to focus on the time slice where such conditions occur. These new conditions may differentially affect the diversification rate of lineages with different morpho‐functional syndromes. A prominent example of these processes occurs in the Mediterranean Basin, where climate arising along the Tertiary/Quaternary transition acted as an environmental filter. In this context, lineages with different syndromes (sclerophyllous and nonsclerophyllous) are hypothesized to have different local diversification rates after the rise of the Mediterranean conditions. We used macroevolutionary methods of time‐dependent diversification on a calibrated local phylogeny accommodating topological and chronological uncertainty to test syndrome‐driven diversification in Mediterranean shrublands from the eastern Iberian Peninsula. We found phylogenetic evidence of higher speciation associated with the nonsclerophyllous syndrome, although extinction rates were similar between syndromes. Consequently a syndrome‐driven local diversification has occurred in shrublands under Mediterranean conditions. The results provide an example of how the integration of the environmental filter in a dated phylogeny may recreate the local history of lineages and help to explain assembly processes in Mediterranean ecosystems.     

STUDIES ON THE POLLINATION ECOLOGY OF TIPULARIA DISCOLOR (ORCHIDACEAE)

Tipularia discolor, a woodland orchid, flowers in mid-summer when reproductive activity is minimal within the herb synusia. Tipularia is insect-pollinated, and artificial crosses showed that seeds are produced after self-pollination, intra-inflorescence pollination, and outcrossing. The single nocturnal pollinator, Pseudaletia unipuncta (Noctuidae), located Tipularia populations within a day or two of anthesis. Pollinators were shown to be capable of utilizing portions of the inflorescences that contained the most nectar. After total nectar resources declined, pollinators were no longer active on the inflorescences, even though flowers and nectar were still available. The mode of pollinator activity seems to be closely related to floral morphology, although the moths are able, early in the flowering phenophase, to successfully obtain nectar without effecting any change in the reproductive status of flowers.     

POLLINATION ECOLOGY OF FOUR DALECHAMPIA SPECIES (EUPHORBIACEAE) IN NORTHERN NATAL,SOUTH AFRICA

The pollination ecology of four Dalechampia species was studied in three areas in northern Natal, South Africa. All species were pollinated by resin- and/or pollen-collecting megachilid bees (Hymenoptera: Megachilidae). The most common of these at all study sites was Heriades sp. (Megachilini), which collected both pollen and resin. This bee was the primary pollinator of D. galpinii and D. volubilis, and a secondary pollinator of D. aff. parvifolia and D. capensis. The primary pollinators of these latter two Dalechampia were Pachyanthidium near cucullatum and P. cordatum (Anthididiini), respectively. These are larger bees that collected mainly resin. Other visitors varied among Dalechampia species and among sites. Pairs of Dalechampia species were often found in sympatry (within 30 m of each other) and shared pollinators to varying extents. “Transfer experiments,” in which we placed inflorescences of two Dalechampia species together, reinforced observations of flower discrimination by bees foraging among naturally occurring sympatric pairs. Heriades sp. showed no obvious discrimination between Dalechampia species, but Pachyanthidium spp. “preferred” the Dalechampia species with the greater resin reward. Occasionally, however, Pachyanthidium would visit less rewarding species. Thus, although sympatric African Dalechampia species showed some pollinator partitioning, it was much weaker than found among New World species, and cannot alone explain the general absence of Dalechampia hybrids in northern Natal.     

BREEDING SYSTEM AND POLLINATION ECOLOGY OF TRIENTALIS BOREALIS (PRIMULACEAE)

Selfing in Trientalis borealis is reduced by spatial separation of stigma and anthers during anther dehiscence and by internal self-incompatibility. Artificial self-pollination resulted in low levels of fruit set (2.0%). Crosses made within patches of plants yielded variable (0–72.7%), but generally low fruit set (x̄ = 21.4%). This may be caused by patches often consisting of a single genet. In contrast crosses made among patches resulted in uniformly high levels of fruit set (x̄ = 84.3%). Pollinator activity was higher at open sites than at heavily shaded sites and was correlated with fruit set. Pollinator activity, however, showed no correlation with seed set. We conclude that the primary pollinators, Halictid and Andrenid bees, play an important role in the breeding system of the plant by promoting outcrossing but that availability or efficiency of pollinators may limit seed set.     

杭州石荠苎和石香薷（唇形科）的传粉生物学比较研究

杭州石荠苎（ＭｏｓｌａｈａｎｇｃｈｏｕｅｎｓｉｓＭａｔｓｕｄａｓ）和石香薷（Ｍ．ｃｈｉｎｅｎｓｉｓＭａｘｉｍ．）是一对种对,前零星分布于浙江,后广布于长江流域以南地区。杭州石荠苎以异花传粉为主,花粉／胚珠（Ｐ／Ｏ）为７５６＝－６１６３;石香薷以自花传粉为主,Ｐ／Ｏ＝１１０。     

POLLINATION ECOLOGY OF A SEAGRASS,THALASSIA TESTUDINUM (HYDROCHARITACEAE), IN ST. CROIX

The reproductive ecology of a dioecious Caribbean seagrass, Thalassia testudinum was studied in St. Croix, U.S. Virgin Islands. Flowering in Thalassia coincided with spring tides with anthesis and anther dehiscence in staminate plants occurring at night. As predicted by search theory, pollen is dispersed in negatively buoyant rafts of pollen grains (that superficially resemble strings of frog spawn) which are bound by a slime of apparent thecal origin. Dispersal of pollen is submarine and approximately two-dimensional along the plane of the substratum. The stigmas on pistillate plants are linear, stiff, and densely papillate; they protrude from the mouth of the subtending leaf. Floral ratios of staminate to pistillate flowers were 60 to 1 with an average distance of 4.0 cm from pistillate flower to the closest staminate flowers. Populations included a high proportion of short shoots with numerous (> 100) leaf scars indicating ages for these axes of up to 3–4 years. Nonflowering shoots can be sexed and frequency of flowering can be assessed from scars of old inflorescences. Preliminary results suggest that there is no regular pattern of flowering, since the interval between flowering events is variable.     

溪流生态系统生态学研究

本文根据6年定位研究的结果,讨论了有关东北山溪生态系统生态学方面的问题,诸如溪流生态系统的组成、结构、能量流动、物质循环、食物网结构与营养能级等。调查了组成生物并对其做了定量分析;描述了能量的消耗途径并绘制了生态系统的能流框图;按营养关系划分了食物链和食物网结构,并根据各类群的生物量计算了不同营养能级的转换效率;按照水体中溶氧变化和水分循环规律建立了相应的动态模型。最后,对经典的将生态系统中生物类群划分为生产者、消费者和分解者三大集团进行了讨论,鉴于事实上每一生物类群分别具有生产、消费和分解等三重作用,因此,建议用生产过程、消费过程和分解过程来表述生物类群在生态系统中的功能作用。       

THE POLLINATION ECOLOGY OF DICENTRA CUCULLARIA

In northeastern Iowa and southwestern Wisconsin the flowers of Dicentra cuculiarla were found to be pollinated almost exclusively by Bombus bimaculatus nectar-foraging queens, which were phenologically synchronized in their emergence from hibernation with the flower's anthesis. Cinematographic and stereophotographic evidence indicated that pollen transfer was effected by the ventral side of the insect's head and anterior thorax contacting essential flower parts and to a lesser degree by the front and middle legs contacting pollen-laden edges of the inner petals. Lepidoptera, Diptera, and small Hymenoptera occasionally encountered on the flowers were ineffective in pollination. Abundant Apis mellifera pollen-foraging workers regularly effected pollination, but being an introduced species it exhibits no naturally developed pollination adaptation to the flower. Nectar spur perforation by B. affinis nectar-foraging queens did not affect plant fertility, and this behavior was related only in part to forager tongue length. Nectar-foraging behavior of B. bimaculalus queens on the flowers was correlated with the phenological development of the annual insect colonies.     

THE POLLINATION ECOLOGY OF ASTRAGALUS CIBARIUS AND ASTRAGALUS UTAHENSIS (LEGUMINOSAE)

Astragalus cibarius and A. utahensis are common perennial species of a widespread legume genus. The pollination of Astragalus has been briefly discussed in the literature, but little work has been done on species in the intermountain West. This study was conducted from 1970–1973 in Utah with mixed and single species populations. The flowers of both species were homogamous and papilionaceous, but the species were different as to color, size, and ultraviolet reflectance. Astragalus cibarius usually flowered 10 days ahead of A. utahensis, but both species flowered earlier than most other plants in the community. Bagging experiments indicated both species were strongly allogamous. Exclosure studies indicated both species relied on insects as pollen vectors. Of the 44 insect species which were observed visiting flowers, only 14 carried Astragalus pollen, and the pollinator fauna varied between study sites. Pollen quantities and distributions on Diptera and Coleoptera indicated a poor potential for pollination. Floral structure, pollen distribution and quantity, and behavior implied that large bees of the families Apidae and Anthophoridae were the primary pollinators. These bees visited only one species of Astragalus when the plants occurred in mixed populations; this constancy may have been related to relative flower abundance. Non-pollinating floral foragers affect other phases of Astragalus life history.     

龙须藤传粉生态学的初步研究

龙须藤（Bauhiniachampionii）的传粉者包括数种蜂类及蝴蝶类昆虫．龙须藤的柱头对花粉的接收高峰大体上与传粉昆虫的活动高峰相吻合．