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After pollination, flowers wither, ovaries swell becoming a dry capsule from where thousands of seeds escape by longitudinal slits.

 

Clones

As many of other plants, some wild French orchid species can reproduce through a vegetative way creating genetically identical individuals either from their tubers (some Orchis and Serapias ), from their rhizomes (Cypripedium, Cephalantera, Epipactis and Epipogium), from stolons (Goodyera repens) or, in the unique event of Hammarbya paludosa, from bulbils located on the leaves .



Orchids and fungi

However, the most common way to reproduce is the sexual reproduction. Pollination happens when grains of pollen, released from pollinias, get in contact with the stigmatic area in the female part of the flower. Genetic material is then transferred, inducing ovule maturation, that can be detected by the swelling of the ovary that will become a capsule. Flowers wither, then thousands of seeds having reached maturity, escape from the slit capsule.
Orchids seeds are very tiny and devoid of nutritive substances. To germinate, seeds must find microscopic fungi that penetrate into the root to form a mycorrhizal association. Such a symbiotic relationship, providing the host with the necessary nutrients, is required by all orchids at the germination phase.

 
Hammarbya paludosa can reproduce from bulbils located at the leave edge.




Visual mimicry of Ophrys insectifera is obvious!

Zygaena pollinating Gymnadenia rhellicani. A pollinia is stuck on its right forelimb.





A bumblebee bearing pollinias on Dactylorhiza fuchsii




Ophrys sulcata ready to be pollinated!
 









Orchids and insects

For most of flowering plants, insects ensure pollen transfer from one flower to another (entomogamy). Pollinias of most orchids include at their basement viscous masses called viscidium. When a pollinator hits pollinias, they strongly stick to it. Then, when visiting another flower, the vector insect carries pollinias and pollen grains get a chance to be in contact with the host stigma so as the fecundation process could start. Consequently, it clearly appears that the orchid ability to attract pollinator insects will determine the species survival. In addition, if the pollinator specifically visits flowers of the same species, reproduction should even be more efficient.

The first attraction strategy used by orchids, as well as by many other flowering plants, consist in offering nutrients to insects, in the form of nectar, or other nutritive substances appreciated by insects. However, as much as efficient it is, this strategy does not allow a great specificity. Some species of genera Neottia or Epipactis emit specific smells reinforcing attraction of their baits. Some orchids as Serapias or Dactylorhiza, which have helmet-shaped flowers attract insects by offering them a shelter to spend the night.

Another method, more sophisticated, consists in imitating the appearance of other flowers producing nectar. Insects attempt to take nectar in vane but even so they are lead to carry away pollinias and trigger fecundation in other flowers. This mimicry avoid the plant to make nectar thus they save the corresponding energy. This artifice is used, for example, by Orchis pallens, Orchis mascula or some Dactylorhiza that resemble the nectar producing flowers of Labiate or Fabaceae.

 
Epipactis distans offering nectar to visiting insects









Orchids attract insects and spiders know about it!

 




Finally an attraction strategy that is proper to Orchids, and particularly to Ophrys, has been reported firstly by Pouyanne* in 1917 : the flower lip mimics the female of the pollinator they want to attract. Then, males come to the flower and attempt to mate with the lip they take for a female of their species (pseudo-copulation). Ophrys are carrying resemblance to female quite far as not only they take the appearance of the female but also their hairiness and their smelling! Actually Ophrys produce substances faithfully reproducing the pheromones cocktail of the female which exert a potent attraction of the corresponding male. This stratagem gives in addition to the flower the advantage of a certain selectivity of the attracted insects.






Solitaries

Some orchids as Limodorum, Neottia, Epipogium and some Epipactis or Serapias as so as Ophrys apifera can fertilize without insects using self-pollination, which means the flower is fertilized by its own pollen (autogamy). This could also happen within the same flower bud (cleistogamy). Self-pollination allows to avoid insect dependence for the plant and thus facilitate colonization of new territories even in the absence or rarefaction of pollinators.

* : Pouyanne, A. 1917 - La fécondation des Ophrys par les insectes.
      Bull. Soc. Hist. Nat. Afr. Nord 8, 6–7.




          More pictures of insects and orchids
 


Colletes attempting to mate with the lip of Ophrys occidentalis



Pollinias of Ophrys apifera lean forward while withering. Thus they can reach the stigma where self-pollination will occur.
 

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