Session having Aline Raynal-Roques as moderator with the participation
of Y. Sell, Günter Gerlach, Mark Whitten and Norris H. Williams,
M. Démares, Jean Claessens et Jacques Kleynen, Thierry Pailler
Reward or not
By Aline Raynal-Roques
For more than two centuries, it has been admitted that the flower rewards
its pollinator. The attractors found in the orchidaceous flowers are
most numerous and diverse. Many of them are puzzling to us. We recognize
attractors useful to the visitor, misleading it, harmful to it or looking
as having no consequence. Can we consider an atractor, even an useful
one, as a reward? The pollinator is unaware of its polllinating role;
the plant has no will of thanking it. Conceiving a compensation help-reward
sounds to limite the relationship Orchid-pollinator to an anthropomorphic
and restrictive view.
Raynal-Roques is a teacher at the Museum National d'histoire naturelle
(Paris) and expert in tropical flore and floral biology.
Fragrance festival in
By Y. Sell
Odour emitted by flowers is the main attractant for insects. Attractive
fragrances as well as pheromones from the orchid are mixtures, in well
determined specific amounts, of various chemical compounds. These fragrances,
issued from tissues mainly located in the labellum, generally constitute
an olfactory guidance towards reproducing organs. A priviledged relationship
is created between flower and insect, that may end into exclusivity
and mainly leads towards orchid pollination.
is master of lecturer in Vegetal Biology at the College of Life at the
'Université Louis Pasteur, Strasbourg, retired. Expert in compared
and experimented morfophology mainly floral ecology. President of the
section of the orchidists of the Amis du Jardin Botanique de Strasbourg
Pollination and fragrances in the tribe Maxillarieae
By Günter Gerlach - Botanischer Garten München - Nymphenburg
Tribe Maxillarieae circumscribes subtribes Coeliopsidinae,
Maxillariinae, Oncidiinae, Stanhopeiane and Zygopetalinae
with often ornamental species. Pollination systems present here are
manifold, rewarding ones are also present as deceptive ones. Among the
rewarding ones there exist oil flowers, offering fatty oils for brood
provision and perfume flowers. Members of the subtribes Stanhopeinae
and Coeliopsidinae are exclusively, members of Zygopetalinae
and Maxillariinae partly pollinated by perfume collecting male
euglossine bees. The mechanisms involved here belong to the most spectacular
ones in plant kingdom. The fragrances serve to select one or very few
bee species of the species inventary present in the respective aerea.
The bees are so special in their preferences that so an efective barrier
against hybridisation evolved. Fragrance analyses of flowers from subtribes
with perfume syndrome are helpful to distinguish the species even when
they are very similar, they give very informative hints for taxonomy
but fail in generic level. To avoid intergeneric hybrids a mechanical
barrier evolved, glueing the pollinaria genus specific at different
parts of the bees body.
Gerlach is a botanical curator at the Botanical Garden Munich in Germany.
His research topics are broadly arranged: from systematics and taxonomy
of the Stanhopeinae and Zygopetalinae going over to pollination
biology, analysis and chemistry in the involved fragrances and floral
oils of several neotropical plant groups and the ecology of the pollinating
Relationships within Tribe Maxillarieae: Lessons from Molecules,
Morphology, and Pollination Biology
By Mark Whitten and Norris H. Williams
The neotropical tribe Maxillarieae contains about 10% of the Orchidaceae
and includes some of the most spectacular and horticulturally important
genera (Oncidium, Odontoglossum, Stanhopea, Zygopetalum, Maxillaria).
Like most Orchidaceae, the classification of these orchids has
been problematic during the last 300 years, in both defining genera
and in grouping these genera into higher categories. DNA sequence data
give us a relatively objective set of data for reconstructing evolutionary
relationships and for constructing a classification system. These DNA-based
phylogenies indicate that gross floral shape and color is often misleading
in constructing classifications, and that shifts to different pollinators
or convergence in pollination systems has confounded earlier classification
systems. In general, the DNA data support traditional classifications
within subtribes that produce legitimate floral rewards (e.g., Stanhopeinae).
In subtribes that contain many species with deceit-based pollination
systems (e.g. Oncidiinae), the DNA-based trees conflict strongly
with traditional classifications. Convergent evolution may produce very
similar floral morphologies in unrelated orchids; classifications based
primarily upon gross floral characters may be misleading.
by M Whitten
by M Whitten
is a botanist at the Florida Museum of Natural History in Gainesville
Florida. His research interests include molecular systematics of orchids
and chemical ecology of orchids Euglossine bees. He is presently
working on the molecular systematics of Maxillaria in collaboration
with colleagues in Mexico, Costa Rica, Ecuador and Brazil.
Pollination in native French orchids
By M. Démares
At first, giving some definitions about general morphology of the orchid
flower and that of an insect, the author approaches pollination
1 – from a descriptive viewpoint,
- at plant level, studying different types of flowers (with long spur,
with medium/short spur, without spur, with hypochile, Ophrys) and their
- at insect level, surveying with examples the main concerned Orders
(Lepidoptera, Hymenoptera, Coleoptera, Diptera),
2 – from a dynamic viewpoint, describing the behaviours of insects
Then he will emphasize the relationship between insect and orchid and
will show the reciprocal adaptation.
of the European orchids. Form and function”
By Jean Claessens et Jacques Kleynen
During the last decade we intensively studied the gynostemium of the
European orchids. The gynostemium is not only important in taxonomy,
but its morphology also determines the way pollination takes place.
Most descriptions of gynostemia of European orchids are based on alcohol
preparates. By examining fresh flower material we gathered many facts,
not only about the morphology of the gynostemia, but also about their
In our lecture we will present several European orchid genera, e.g.
Cephalanthera, Corallorhiza, Epipogium and Ophrys
in various ways: we made photographs of habitus, flower, gynostemium,
longitudinal sections of the flower and microscopic sections of the
gynostemium. Form and function of the flower are closely connected.
Examples are given to show how minor changes in the construction plan
of a gynostemium can determine the way pollination takes place. For
maximum insight and comparison we will present two dia slides on two
et Jacques Kleynen are nature photographers specialised in extreme macrophotography.
interactions in an oceanic Island.
By Thierry Pailler
Universiteé de la Réunion - Peuplements Vegetaux Et Bioagresseurs
En Milieu Tropical
The orchid flora of Réunion Island mainly originated from Madagascan
colonists. At present, it contains more than 120 native species, half
of which are endemics. The sub-tribe angraecinae is represented by 7
genera and 62 species. Jumellea is one of these genera which contains
9 endemic species. Four species are short spurred (8-50 mm in length),
which is a feature of the phalenophilous pollination syndrome and five
are long-spurred (90-150 mm in length), which is a feature of the sphingophilous
pollination syndrome. A set of experiments (hand pollinations, pollinator
exclusion experiments and emasculation in natural conditions) on the
reproductive biology of 8 species of Jumellea revealed that short-spurred
species need pollen vectors to reproduce successfully, while long-spurred
species are self-fertile and do not require any pollinators to achieve
reproduction. The study of floral features of both short and long spurred
species shows the loss of odour and shorter floral duration in long
spurred species. The study assumes the lack of long tongue pollinators
(hawkmoth) during the long spurred orchids colonization event. The breakdown
of the orchid - sphingid co-evolution will be discussed in the context
of island existence and Baker’s law.
T. Pailler. Dr in Plant Reproductive Biology. Lecturer at La Réunion
University (France, Indian Océan). Member of the Orchid Specialist
Group of IUCN. Member of La Réunion Island Herbarium.
Main interest: Orchid biology, orchid ecology and plant conservation.
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