The orchid's internal clock
It is in the orchid that the orchid's internal clock triggers the production of haploid cells (n), called gametes.
Then, to pollinate the flower orchids develop two strategies: - passive or self-pollination - the pollen active (growing), depending on its majority-insect pollinators.
And once again in the flower, that meet the male and female gametes, ending the cycle of reproduction by seed formation (as a result of fertilization of an egg).
So the seeds are the source of a new generation of sporophytes (2n). We want to attract the reader's attention on the effect of the degeneration of lineages of orchids, dating more than one century, living in conditions of artificial cultivation in greenhouses.
To avoid this problem one must understand the basic cause - lack of genetic recombination. In Figure 1, introducing the life cycle of orchids, we can see that the multiplication by sexual reproduction is relatively rare in the Orchidaceae family , especially in greenhouses, where vegetative propagation is more common.
Nevertheless, sexual reproduction is of great importance for a mixing of genes and provides intra-specific diversity * (for example, the difference between parents and their offspring). It is not uncommon for several specimens of one species of orchids to have been well harvested in different locations.
The presence of several specimens of a species (at any stage of the cycle: seeds, a juvenile or adult) can then be the offspring of genetically different and study its intra-specific diversity in culture. Here are the stages of ontogeny we have in theory but rarely in reality seeds - protocorms - Shoots - Seedlings - Adults orchids.
by Marpha TELEPOVA-TEXIER
Département des Jardins Botaniques et Zoologiques du Muséum national d’Histoire naturelle, USM 0602, case postale 39, 57 rue Cuvier, 75005 Paris; telepova@gmail.com
Then, to pollinate the flower orchids develop two strategies: - passive or self-pollination - the pollen active (growing), depending on its majority-insect pollinators.
And once again in the flower, that meet the male and female gametes, ending the cycle of reproduction by seed formation (as a result of fertilization of an egg).
So the seeds are the source of a new generation of sporophytes (2n). We want to attract the reader's attention on the effect of the degeneration of lineages of orchids, dating more than one century, living in conditions of artificial cultivation in greenhouses.
To avoid this problem one must understand the basic cause - lack of genetic recombination. In Figure 1, introducing the life cycle of orchids, we can see that the multiplication by sexual reproduction is relatively rare in the Orchidaceae family , especially in greenhouses, where vegetative propagation is more common.
Nevertheless, sexual reproduction is of great importance for a mixing of genes and provides intra-specific diversity * (for example, the difference between parents and their offspring). It is not uncommon for several specimens of one species of orchids to have been well harvested in different locations.
The presence of several specimens of a species (at any stage of the cycle: seeds, a juvenile or adult) can then be the offspring of genetically different and study its intra-specific diversity in culture. Here are the stages of ontogeny we have in theory but rarely in reality seeds - protocorms - Shoots - Seedlings - Adults orchids.
by Marpha TELEPOVA-TEXIER
Département des Jardins Botaniques et Zoologiques du Muséum national d’Histoire naturelle, USM 0602, case postale 39, 57 rue Cuvier, 75005 Paris; telepova@gmail.com