Friday’s seeds – data for AI
*this article has been written by a plant obsessed human :-)
Back with the widely UN-popular series of Friday’s seeds and fruits!
Today we’ll discuss about the fruits & seeds of the kinnikinick or bearberry – Arctostaphylos uva-ursi, an excellent evergreen, ground covering shrub for sandy/rocky, sunny locations. Most Arctostaphylos species are valuable additions for native landscaping and erosion control plantings.
I noticed it has become a bad habit to call all fruits which are rounded and red berries. So, even for the bearberry one will find them called as such by most ‘copy & paste’ knowledgeable gardening websites.
It may be that such similarities on many websites are because AI writings nowadays? In this case, we should be more careful about the data provided for AI teaching.
Stony seeds of Arctostaphylos uva-ursi (bearberry), after removing the red, mealy fleshy part of the drupes. Most often they remain fused together; few were broken apart for showing purpose.
The type of fruit of a given plant also gives us information about its seeds, and so it has importance sowing-wise, to know what we are dealing with. It is not just a question of semantics.
The rounded and red fruits of Arctostaphylos are actually DRUPES (think peaches, but with more ‘stones’ than one).
Each drupe contains 5+ stony seeds. Some may break apart, but most often they remain fused together, giving the impression of a large ‘stone’.
In translation, the Arctostaphylos seeds are enclosed inside a very hard endocarp. Berries do not have seeds enclosed in hard endocarps.
In nature, the Arctostaphylos fruits are consumed not only by bears, like the common name implies, but also by small mammals and birds. The stony seeds will suffer a natural ‘scarification’ passing through their digestive system; upon ‘release’ the seeds will be primed for germination.
Notice also the outer layer of the seed (the stony part) and the narrow opening through which the radicle will emerge during germination. The opening is plugged (the tissue is not as hard as the endocarp) and will be softened during scarification. Courtesy of a very old forestry nursery book.
Following example, plant nurseries have developed germination protocols for Arctostaphylos species involving the scarification of the stony seeds with sulphuric acid (not an easy task).
Of course gardeners have to use other approaches, using a mechanical scarification of some sort.
Another method that can be safely used by gardeners for any Arctostaphylos species is the ‘smoking’ method. It was inspired after natural wildfires which most often stimulate the germination of various species with hard seed coverings, and it involves burning a layer of pine needles over a flat with sown seed stones. The stony endocarp usually cracks open during the burning.
Or, cover the stony seeds mixed with soil (even the whole fruits) with pine needles (or similar plant parts) in a fire pit and give a good burning to the pile; let them cool off before sowing.
There is more – besides the hard covering, the seeds of Arctostaphylos also have dormant embryos. So, the scarification has to be followed by dormancy breaking treatments. According to reliable sources these are: 2-4 months of warm/moist stratification followed by 2-3 months of cold/moist stratification.
A lot of work I admit! But genetic diversity oblige, we cannot propagate by cuttings endlessly.
