The floral biology ofThelymitra epipactoides (Orchidaceae), and the implications of pollination by deceit on the survival of this rare orchid

Thelymitra epipactoides has a highly variable visual display achieved through polychromatic flowers and variable inflorescence size, bearing between 7 and 31 flowers, which attract foraging polylectic bees. Only bees of the genusNomia were observed carrying pollinia and successfully pollinating the orchid. The genusNomia contains polylectic, pollen gathering species that store pollen in both the crop and scopa on the hind legs. The absence of a reward for the bees indicates the orchid is relying on deception to attract visitors. The relationship of deception to mimicry is discussed. Once on the flower, tactile, visual and possibly olfactory stimuli direct bees to the false anther formed by the voluminous column wings, where morphological adaptations of the flower ensure that the pollinarium is deposited on the gaster of the bee to effect pollination. — The lack of seed set observed on the Victorian coast appears to be due to the absence of pollinators from the heath and grassland communities in which the orchid grows. This may well be a consequence of the reduced number of plants flowering in the community (a result of the elimination of fire at these sites), thus not maintaining a floral community attractive to potential pollinators.     

Floral mimesis inThelymitra nuda (Orchidaceae)

Insect pollination occurred inThelymitra nuda R. Br. on sunny days when the ambient temperature exceeded 20 °C. The flower buds on a raceme opened subsynchronously displaying the brightly-colored, actinomorphic perianth and exposed the contrastingly-colored, scented and ornamented column. InT. nuda the staminodes and the filament of the fertile stamen are fused to one another producing an inflated hood over the anther. This staminodal hood is terminated in two non-ornamental, but brightly-colored, central lobes and two terete lateral lobes bearing approximately 400 white trichomes. Each trichome bears a double chain of 30–40 spherical, rugulose cells. Female bees, in the genusLasioglossum (Halictidae), were observed to land directly on the hood and curled their bodies around the four lobed tip of the staminodal complex. The bees attempted to forage on the lobes as if they were collecting pollen from fertile, poricidal stamens. These bees applied thoracic vibration to the yellowish central lobes and actively scraped the trichome clusters (Pseudopollen) with their forelegs. Bees carried the pollinaria ofT. nuda dorsally on their abdomens. Abdominal contact with the rostellum appeared to occur when the female bee disengaged herself from the staminodal hood. Observations made of bees on co-blooming flowers, and analyses of pollen loads collected by bees suggested that the orchid flower mimics the guild of blue-purple flowers that lack floral nectar but offer pollen in poricidal anthers. The models ofT. nuda are co-bloomingLiliaceae in the generaDichopogon andThysanotus. However, nectarless, buzz-pollinated flowers are also extensively distributed over the orchid’s range. More than 30% of the flowers in theT. nuda population had their pollinaria removed, suggesting a high capacity for cross-pollination in an orchid genus usually considered to be self-pollinated via mechanical autogamy. This study confirmed previous predictions that column modifications represented a trend towards pseudanthery.     

Pollination ofOphrys (Orchidaceae) in Cyprus

In the southern part of Cyprus the pollinator —Ophrys (Orchidaceae) relationships and its specifity have been investigated from the end of February until the middle of March 1986. 12Ophrys spp. were found. To date, only a single pollinator reference has been reported from this island. We found the following pollinators:Melecta tuberculata (Ophrys kotschyi),Eucera dimidiata (Ophrys flavomarginata),Eucera gaullei (Ophrys umbilicata),Eucera paulusi (Ophrys bornmuelleri),Anthophora erschowi (Ophrys elegans),Andrena torda (Ophrys sicula =O. lutea subsp.minor),Andrena cinereophila (Ophrys fusca, small-flowered),Andrena flavipes (Ophrys israelitica),Andrena morio (Ophrys iricolor andOphrys transhyrcana),Andrena bimaculata (Ophrys sphegodes aggr., probably formerly confused withO. transhyrcana). Most interestingly, it could be verified thatO. flavomarginata/O. umbilicata, O. bornmuelleri/O. levantina andO. transhyrcana/O. sphegodes aggr. (possiblyO. sintenisii) are different biospecies. This is a result of genetic isolation due to varying pollinators, and of differences in flower morphology.     

Observations of the floral biology ofPrasophyllum odoratum (Orchidaceae,Spiranthoideae)

Prasophyllum odoratum is a vernal, nectariferous, terrestrial orchid that flowers profusely six to eight months following cyclical fires that disrupt sclerophyll woodlands. The morphology of the column and pollinarium is indicative of taxa placed within the subfam.Spiranthoideae. The orientation of the pollinaria to the stigma appears to prevent mechanical self-pollination. Both cross- and self-pollination appear to be effected by insects that forage within the brightly-colored, scented, non-resupinate flowers. Ants and drosophilid flies remove nectar, but do not appear to transport pollinaria between flowers. The primary pollinators are polytrophic flies in the fam.Syrphidae and opportunistic male bees in the genusLeioproctus (Colletidae). Approximately 52% of the flowers on a raceme set seed. The comparatively short floral tube ofP. odoratum reflects the dependence of this species on short-tongued insects to effect successful dispersal of pollinaria.     

Insect pollination and floral mechanisms in South African species ofSatyrium (Orchidaceae)

The morphologically diverse flowers in the genusSatyrium reflect adaptations to a wide range of pollinators. Several recently discovered pollination systems inSatyrium are described and illustrated here; these include pollination by solitary bees, carrion flies, butterflies and moths. Two basic types of floral mechanism are recognised inSatyrium: (1) Species pollinated by lepidoptera and birds have long floral spurs and plate-like viscidia seated in lateral rostellum notches; these viscidia become attached to the proboscis or bill of the pollinator. (2) Species pollinated by flies and bees have relatively short floral spurs and globose viscidia seated in terminal rostellum notches; these viscidia become attached to the face, thorax or eyes of the pollinator.     

New and noteworthyHabenaria spp. (Orchidaceae) from New Guinea and adjacent islands

5 new taxa ofHabenaria, namelyH. bougainvillae, H. elongataR. Br. var.leptophylla, H. ensigera, H. rechingeri andH. trichoglossa, are described and illustrated, with reference to affinities to related Australian and Indo-malayan species. The occurrence in New Guinea of severalHabenaria spp. typical for a savanna-like vegetation, led to look more thoroughly at these taxa:H. elongataR. Br. andH. ochroleucaR. Br., considered so far to be endemic in Northern Australia, andH. khasianaHook. f., hitherto only known from southeastern Asia.Studies in the subtribeHabenariinaeBentham (Orchidaceae), 2.—Part 1: Candollea34, 357 (1979).Dedicated to Hofrat Prof. DrKarl Heinz Rechinger on the occasion of his 80th birthday. — On April 30, in the year 1927, the author and his brotherOtto Renz metKarl Heinz Rechinger on a small steam-boat in a stormy Aegaen Sea, travelling from Piraeus to the Northern Sporades Islands:Karl Heinz with destination to Chelidromia, the author andO. Renz to Skopelos. By this lucky chance a lasting friendship began.     

Pollinator limitation and position dependent fruit set in the high Andean orchidMyrosmodes cochleare (Orchidaceae)

Myrosmodes cochleare is a terrestrial orchid restricted to high elevations of the northern Andes. It is self-compatible but not autogamous. Flowering begins at the apex of the inflorescence, but flower size increases steadily towards the base. Fruit set of selfed flowers was found to increase significantly from the apex to the base of the inflorescence. Open-pollinated fruit set was significantly lower than hand-pollinated fruit set overall, but the highest levels occurred in the middle of the inflorescence. Eumenid wasps and a calliphorid fly were observed to pollinate the flowers, but visits were rare and occurred only during infrequent warm periods.     

Pollination by deceit in nutmeg (Myristica insipida, Myristicaceae): floral displays and beetle activity at male and female trees

Pollination by deceit in Myristica insipida, a beetle-pollinated nutmeg, was hypothesized to operate on intersexual differences in flower production and longevity, producing a daily fluctuation between floral display maxima and minima. Sticky traps were used to continuously monitor beetle activity. Flower production and naturally occurring intersexual differences in display were recorded. Male and female trees flowered in synchrony producing daily display maxima at 1800-0600 and display minima at 1400-1800. Rewarding male trees produced three times the number of flowers of female trees, but the greater longevity of female flowers reduced the intersexual difference in display maxima to a factor of two. There was no intersexual difference in display minima. Beetles were demonstrated to be sensitive to differences in both maximum and minimum displays on rewarding male trees, a necessary prerequisite for directional selection on display size. Beetle captures were significantly higher at male trees during floral display maxima, and no intersexual differences in capture rate occurred during floral display minima. However, capture rates at male trees did not decline as predicted, and the pattern of captures was consistent with crepuscular activity. Beetle captures at male and female trees were lower from 1800 to 0600 and 1000 to 1400, and higher from 0600 to 1000 and 1400 to 1800, but the differences were only significant at female trees. These data suggests that foraging errors are numerous, frequent, and the result of overall foraging activity.     

The unique pollination ofLeporella fimbriata (Orchidaceae): Pollination by pseudocopulating male ants (Myrmecia urens,Formicidae)

Leporella fimbriata is a self compatible orchid of southern Australia. It is dependant across its range on unique pollination by sexually attracted male winged antsMyrmecia urens, which pseudocopulate with the flower. Typical pollination sequences began with an initial circling then zig-zag flight to the flower. Vectors usually alighted on the inflorescence stem and quickly crawled to the flower where they adopted a copulatory position sideways along the wide labellum, pseudocopulatory probing immediately followed. In this position pollen carried on the thorax was deposited on the stigma. Departure from the labellum usually resulted in pollinium removal. Pollinator movements were restricted and the distribution leptokurtic with a mean of 3.141 ± 4.59 m. Pollination was widespread but variable from site to site and season to season with a maximum of 70% of all flowers being pollinated. Pollinator limitation is indicated. Traits essential for this pollination interaction include the coincidence of orchid and ant geographic distributions and the coincidence of flowering with the flight period of the ant. The production of pheromonelike substances and the distinctive floral morphology are also essential for attraction and manipulation of male ants. The ant mating system which the orchid can exploit is also important.     

Floral evolution and phylogeny in the tribeThelymitreae (Orchidaceae: Neottioideae)

The Australian orchid tribeThelymitreae, composed ofCalochilus, Epiblema, andThelymitra, is unique in theOrchidaceae because of the presence of a mitra or staminodal complex. Evidence from floral structure suggests thatEpiblema andThelymitra are sister genera and thatCalochilus is derived from aThelymitra ancestor. A Gene Pool Vortex model and a hypothetical phylogeny illustrate that introgressive hybridization, allopatry, and long distance dispersal have played a major role in the evolution of the tribe. Pollination and hybridization in the tribe are discussed with major emphasis on floral mimicry.     

Pollination ofDianthus gratianopolitanus (Caryophyllaceae)

Pollination ofDianthus gratianopolitanus was studied in a population of the Swiss Jura mountains. Pollinators of this plant species are reported here for the first time. The flowers were not only visited by butterflies as postulated in the literature, but also by diurnal hawkmoths (Macroglossum stellatarum) and by diurnal and nocturnal noctuid moths. — Nectar is sucrose-dominant, the sugar concentration is moderate but the amino acid concentration is high. Nectar characteristics correspond well with the syndrome ofLepidoptera-pollinated flowers. — Field observations and flower characters (colour, range of the calyx length) suggest thatDianthus gratianopolitanus is an intermediate species in the transition of butterfly to moth pollination. — Lack of reproductive success inDianthus gratianopolitanus can not be attributed to lack of suitable pollinators.     

Pollination by deceit,floral sex ratios and seed set in dioecious Rubus chamaemorus L.

Summary Male and female flowers of the dioecious perennial herb Rubus chamaemorus L. are similar in general appearance. However, female flowers are somewhat smaller, do not produce any pollen, and contain very small amounts of nectar. Syrphids and bumblebees, which are important pollinators of R. chamaemorus, showed a strong preference for male flowers. Male flowers were also less often rejected by flower visitors than were female flowers, and two different groups of syrphid species stayed longer in male than in female flowers. These observations suggest that female flowers of R. chamaemorus attract pollinators by deceit.Hand-pollination experiments indicated that pollen availability limited seed production of R. chamaemorus in female dominated habitats but not in areas with an equal floral sex ratio. We suggest that the relative importance of factors limiting female reproductive success is not constant, but is influenced by the floral sex ratio of the population. This should apply also to other dioecious species that show variable sex ratios on either a local or regional scale.     

Bird pollination in South African species ofSatyrium (Orchidaceae)

Field observations showed that three South African orchid species,Satyrium carneum, S. coriifolium andS. princeps, are pollinated by sunbirds. Foraging sunbirds insert their bills into the labellum chamber of the flowers and suck nectar from the labellum spurs with their tongues. The column overarches the entrance to the labellum and pollinaria become affixed to the upper mandible of the bill. Birds often attempt to remove pollinaria by rubbing their bills against a branch, but are mostly unsuccessful due to the large plate-like viscidia which attach the pollinaria very firmly to the bill. Other modifications for bird pollination in theseSatyrium species may include the red, carmine or orange colour of the flowers, sturdy inflorescence stems used for perching and large amounts of dilute nectar in the spurs. EachSatyrium species was pollinated by several species of sunbird, and despite some differences in flowering time, occasional hybrids occur at a site whereS. carneum andS. coriifolium share the same sunbird pollinators.     

Orchis prisca (Orchidaceae), eine neue Art aus Kreta

Orchis priscaHautzinger is described as a new diploid species from Crete, related toO. patens andO. spitzelii.

     

Aspects of floral structure and phenology in the genusConophytum (Mesembryanthemaceae)

The complex floral structure in the southern African genusConophytum (Mesembryanthemaceae; 77 spp.) is described in detail and assigned to three basic floral types, two of which can be divided into two subtypes. Correlations between structural features and phenological patterns are demonstrated and discussed in the family context as well as in relation to the systematic subdivision of the genus.     

A new species ofLiparis (Orchidaceae) from India

Liparis indiraii spec. nova from India is close toL. alata A. Rich. andL. atropurpurea Lindl.     

Pollination by a hugging mechanism inVigna vexillata (Leguminosae-Papilionoideae)

The pollination ofVigna vexillata (Leguminosae-Papilionoideae) by a carpenter bee,Xylocopa gualanensis (Hymenoptera-Anthophoridae) was studied in a secondary vegetation in Costa Rica. The bees were observed foraging onV. vexillata only in early mornings. Visits on individual flowers lasted about 7–8 seconds. Flower—pollen vector interactions are described and illustrated. By its pressure on the left-hand wing- and keel-petal in the asymmetrical flower, the weight of the bee causes the upper bearded part of the style along with the upper free parts of the stamens to slip out of the rigid keel-beak, hugging the bee over the dorsal part of its head and thorax. The occurrence of nototribic pollination inVigna and related genera is discussed.     

Pollination disruption by European honeybees in the Australian bird-pollinated shrubGrevillea barklyana (Proteaceae)

European honeybees (Apis mellifera) were less efficient pollinators ofGrevillea barklyana than nectar-feeding birds. Nectar-collecting honeybees did not contact reproductive parts of flowers. Pollen-collecting honeybees preferentially visited malestage flowers but rarely visited female-stage flowers. Fruit set on caged inflorescences that allowed access to honeybees but excluded birds was reduced by more than 50% compared to inflorescences that were visited by both types of visitors. Further, fruit set on caged inflorescences was less than on bagged inflorescences that excluded both birds and honeybees, indicating that pollen removal by bees decreased opportunities for delayed autonomous selfing in the absence of birds. Although fruit set was not pollen-limited at the study site, pollen removal by honeybees would decrease fruit set in small populations where birds are scarce. In addition, pollen removal by honeybees would reduce opportunities for outcrossing and reproductive success through male function. Although honeybees have been in Australia for insufficient time to have exerted selection on floral traits, evolutionary shifts in response to these animals are likely to occur in the future.     

Chromosome numbers in AustralianEuphrasia (Scrophulariaceae)

Chromosome numbers for six Australian taxa ofEuphrasia have been determined. Improved staining techniques have shown that numbers for four of the taxa published previously by the first author were incorrect. The investigated taxa show high ploidy levels with an apparent base number of x = 11, the same as for the genus outside Australia.Dedicated to Prof. DrElisabeth Tschermak-Woess on the occasion of her 70th birthday.     

Karyological differentiation and speciation in C. MediterraneanAnacamptis (Orchidaceae)

Anacamptis pyramidalis is a variable and wide-spread European-Mediterranean taxon. Beside a dominant cytotype with 2n = 36 it includes cytotypes with 2n = 54 and 63 in northern Tuscany (and the Eastern Pyrenees) and one with 2n = 72 on Malta. In contrast,A. urvilleana, formerly often misidentified and included inA. pyramidalis, is a monomorphic and distinct species, endemic to the Maltese Islands. It has 2n = 36, can be clearly separated by morphological and anatomical features and is isolated from partly sympatric populations ofA. pyramidalis with 2n = 72 by differences in chromosome number, flowering time and habitat preference.