Processing - cleaning and testing the seeds
1. Assessment of likely seed storage characteristics
The largest of these two seeds is Orthodox (Acer platanoides, the Norway Maple) and the smaller one at the top (Acer pseudoplatanus, the Sycamore) is intermediate.
Aesculus hippocastanum - a recalcitrant species
Most species have seeds that stay viable when dried to the low moisture contents necessary for long-term storage. These are termed 'orthodox' species. However, there are two types of species that cannot be conserved long-term in a seed bank namely recalcitrant and intermediate species. Collectors keep an eye open for such likely problem species when in the field. However, as a precaution and before the collections are despatched, the collectors send a list of species collected to the Millennium Seed Bank where it is checked against the Seed Information Database for seed storage behaviour.
If a species has been collected that is closely related to a known recalcitrant or intermediate species, then on arrival its seeds are tested before drying. This test involves viability tests before and after drying on a small sub-sample of the collection. Similarly, if a collection arrives that has very large seeds (which is an indication of the possible risk of being killed by desiccation) then it might be tested for its storage behaviour.
More information on identifying desiccation-sensitive seeds
