Data and Systematics of genera and species of Laeliinae
by Cassio van den Berg
In order to evaluate generic alliances in Laeliinae and relationships
to select outgroups in Epidendreae, we gathered the datasets.
Although relationships between Laeliinae and outgroups were well-suported,
within the subtribe sequence variation was small, considering the broad
taxonomic range studied. In both plastide and nuclear phylogenies many
branches collpased and only a few are well-supported. The sister group
of Laeliinae is shown to be Arpophyllum, Pleurothallidinae, Ponerinae.
The phylogeny within the Cattleya alliance is clarified,
suggesting that previous ITS data contained some paralogous sequences.
DNA data allow proposing new generic alliances, and redefining species
van den Berg is professor at the University of Feira, State of Bahia,
does my orchid have more than one name?
by Gary Yong Gee & Roger Sawkins
When orchids were initially classified the morphology of the flowers,
and to some extent the plant, were the main characteristics used. Recent
analysis of DNA sequence data has been used to better show the relationships
between genera, particularly whether common or different ancestors are
involved. Nowadays taxonomists look towards classifying species in monophyletic
rather than paraphyletic genera.
Large genera such as Dendrobium, Bulbophyllum, Laelia
and Oncidium have had numerous species included based upon floral
morphology. Analysis of DNA sequence data shows that many genera are
paraphyletic, so taxonomists have been reclassifying the species. Individuals
however may interpret the DNA sequence data differently. This has resulted
in numerous changes to the generic names of many of the species grown
In recent years authors such as Mark Clements, David Jones and Dariusz
Szlachetko, as well as Mark Chase and Cassio van den Berg have published
changes to a large number of species. However authors such as Stephen
Hopper and Andrew Brown, as well as Guy Chiron and Vitorino Castro have
challenged some of these changes and published others of their own.
The speaker illustrated many of the changes with photographs and discuss
the advantages and disadvantages of the new classifications. He will
also discuss the issues which face growers and hybridizers when the
names of some species do not remain static.
Gee has been a judge for many years. He has over 30.000 photographs
of orchid species and has traveled to many parts of the world. He writes
for the Orchid Species Bulletin each month and is co-author of the Cd
Diverse Mycorrhizal Symbionts In European Forest Green Orchids (Neottieae)
Suggests A Partial Mycoheterotrophy
by Marc-André Selosse
Achlorophyllous mycoheterotrophic orchids (MHOs) reverse the usual mycorrhizal
symbiosis (where plants exchange photosynthates against mineral nutrients)
by recovering carbon from the fungus. MHOs evolved at several times
by shifting from usual orchid rhizoctonia partners to other basidiomycetes
forming ectomycorrhizae (ECM) with trees. MHOs are specific to narrow
fungal clades that are mycorrhizal with surrounding green plants, which
provide carbon to both heterotrophs.
We investigated symbionts of chlorophyllous species phylogenetically
related to MHOs from the forest orchid tribe Neottieae, that includes
MHOs like Neottia nidus-avis or Cephalanthera austiniae,
and photosynthetic species, e.g. in the genera Limodorum, Epipactis
and Cephalanthera. Root symbionts were identified by ITS amplification
and sequencing. Limodorum abortivum is rather specifically associated
to Russulaceae, but may contain additional ascomycetes; in addition,
photosynthesis experiments suggested that this orchid, although photosynthetic,
needs a carbon flux from the fungus. We also studied symbiont diversity
in three Epipactis and two Cephalanthera species from
European populations, including several achlorophyllous and subterranean
individuals. An unexpected fungal diversity was found, including various
basidiomycetes such as Sebacinaceae, Thelephoraceae, Russulaceae…
as well as Ascomycetes belonging to Helotiales, Pezizaceae (e.g. truffles
– Tuber sp.). Ascomycetes were confirmed to form pelotons within
orchid root cells by TEM analysis. These orchids are therefore low specificity
associates of ECM fungi. Since green orchids have symbionts similar
to the achlorophyllous and subterranean individuals, which are mycoheterotrophic,
some green Neottieae could partly behave as MHOs. Isotopic data obtained
on a Cephalanthera damasonium population suggests that both achlorophyllous
and green individuals mainly rely on fungal carbon for their growth.
Among Neottieae, ECM symbionts perhaps replaced the Rhizoctonias
as these orchid shifted to forest niches, possibly as an adaptation
to low-light habitats. We speculate that this entailed a predisposition
to mycoheterotrophy by exploitation of tree photosynthates.
Selosse is Master of Conferences at Paris VI University and leading
the research "Systématique, Adaptation et Evolution"
(Sistematic, Adaptation and Evolution) at the Natural History Museum.
of The Flowers and Sexuality in Orchids
by Albert Roguenant
The concept of respiration which supposes that the orchid flower moves
on a 180° angle appears obsolete. We observed that – the lip
orientates either downward or upward – the symmetry plane orientates
vertical – the flower plane orientates tangential to the inflorescence
envelope. We propose the following terminology : the orientating movements
of the flower, as a whole, correspond to the gyration – the flower
having its lip orientated upward is said epigeous– in the opposite
case it is said hypothyroid. This phenomenon probably extends to other
families of hygroscopic flowered flowering plants.
We observe several other types of movements not indicated by authors.
We will show that the 180° angle is but a particular case.
We have recorded several movements leading to fit the flower to a given
- large range movements:
- the pedicel and/or the ovary is twisted
- bending of the pedicel and/or of the ovary;
- complementary movements, of small range
- various movements drawing the flower to fit to its optimal position
related to 1) vertical and 2) the inflorescence envelope.
Albert Roguenant works with the floral biology
of orchids. He is the co-author of a book on orchids pollinator, recently
and phylogeny in orchids
by Daniel PRAT
The number of described orchid species increases since several decades.
Hybrids between taxa identified by morphological traits as species or
even genera are observed. This means probably that systematics needs
of taxon ranks. The species concept has got several definitions in plants
(Judd et al., 1999); the genetic isolation of species remains the most
suitable concept. The development of genetics should help botanists
in the description of taxa with a proper rank. Most recent studies dealt
with phylogeny. With phylogenetic approaches, genetic relationships
are established, more or less precisely, according to the set of taxa
and to the genetic markers used. As the radiation of some genera like
Ophrys, Epipactis. occurred recently, few genetic changes can
be found in the sequences used for phylogenetic studies (Pridgeon et
al., 1997; Soliva et al., 2001; Bernadinos et al, 2004). The genetic
proximity of taxa does not mean they belong or not to the same species.
Genetic isolation of taxa should be considered. Gene flows are investigated
to determine whether taxa exchange genes (Soliva and Wildmer, 2003).
The low genetic structure observed at the species levels reveals pollination
among taxa even if specific pollinators are presumed. Relationships
between Ophrys gresivaudanica and the close taxon Orchis
fuciflora will be presented. Conclusions on the interactions between
phylogenetic and systemactics considerations will be drawn.
Professor Daniel PRAT is the director of the Higher Plant Genome and
Evolution Lab, Biology Department, University Claude Bernard, Lyon (France)
In charge of the Scientific Commission of the French Orchid Society
kind of reproduction (print, digital or anyone other) of any
type of material of this site - texts, layout, photos, images
and others - is strictly forbidden without previous written
permission by the authors.