I have a Chinese chestnut tree (Sterculia Monosperma) that is about 8 meters tall. We are enjoying the nuts now as well as the striking red seed cases. My question is, is this tree self pollinating? The fruit set was not very great, and mostly on lower branches. While we only have the one tree, there are almost certainly some in the neighborhood as we were asked if we wanted to go into the woods to pick some.

Good question. I didn't know the answer so I've been looking.  The genus Stericula is said to have unisexual as well as bisexual flowers, and can be monoecious or dioecious. This particular species, S. monosperma, is listed as having unisexual flowers, but I don't know botany details that well and I don't know if that means that your tree has only female flowers. I can't find a reference to whether its monoecious (self pollinating) or dioecious.  I'm going to ask a couple of botany expert contacts. 

 

Keep in mind that pollination is not the only factor for quanity and quality of seed production.  Nutrition through soil fertility and the extensive mycorrhizal fungal networks that form in association with roots in the natural environment can make a big difference.  If its a single, out-sourced, planted tree in an altered, disturbed, nutrient-depleted soil environment, it may be at a disadvantage, even with adequate pollination. 

 

When you 'go into the woods to pick some', take a bag and a trowel and bring back some native soil and root fragments to spread around your tree for inoculation of the beneficial biology that goes along with it.  Spread compost and wood chips mulch on top of that to create a living soil environment as best possible. 

 

Difference Between Unisexual and Bisexual Flowers | Definition, Characteristics, Pollination, Examples (pediaa.com)

Thanks for the tips and research. Our soil has come back after 8 years of no spray, but more inoculation is a good idea. Seems very likely there is a set of organisms that are copasetic with chestnuts.   

On 9/27/2021 at 1:13 PM, islandguy said:

Thanks for the tips and research. Our soil has come back after 8 years of no spray, but more inoculation is a good idea. Seems very likely there is a set of organisms that are copasetic with chestnuts.   

Yes, definitely there will be species- and site- specific as well as general beneficial soil biology in action. But it requires more than no-spray to manage and cultivate.  Inoculation with native soil is good if possible, and insuring that the microbes have conditions condusive to flourish. Which includes soil moisture, organic matter content, aeration - no compaction or pavement.  To go all out, consider engineered fungal-dominant compost and compost extract and tea.  This plus multiple mixed species cover cropping is the state of the art in the emerging science of complexity and organic soil building.  See "Soil Food Web" info and other resources listed in the Regenerative Ag discussion on this forum.

 

TV farming member Evolare ( FB vendor Best Garden State)  recently informed me that he has a cover crop expert developing seed mixes for tropical crops and conditions. This is a huge development for organic farmers here who are in touch with the emerging regen ag approach. They are also now marketing a high quality vermicompost, as well as complete organic fertilizers and other organic grower supplies.

 

'Jack compost' you know, from Natural Agriculture in Mae Taeng. The batch I bought last week was not as thoroughly decomposed as before, a lot of course solid wood fragment content. Check it to see what you are getting. 

 

Finding The Mother Tree is a fascinating new book just out this year from PhD forest ecologist Suzanne Simard. 

Your female tree may be lonely and needs a partner for reproduction. 

 

This just in, from my botany guru:

 

Don,

I think all members of the genus Sterculia are mostly or all dioecious (male and female trees). So pollination from another tree is required.

Hope you’re well.

Warm regards,

Matt

 

Matt Ritter, PhD | Distinguished Professor | Biological Sciences Department

California Polytechnic State University | San Luis Obispo | CA 93407

I’m propagating seeds from the tree so I could wait to identify a male and then plant nearby. Another angle would be to get some bees. So far no luck with attracting them to our empty hive, but someone here sells beehives with small stingless native bees good for pollinating smaller flowers (he has a cacao nursery). Since we did get moderate fruiting there must be a male plant not far away. This is one of the few trees I have where I would be excited to get a much larger yield. Chestnut along with chocolate sapote and finger lime.

There are local beekeepers with whom you can arrange to have set up hives on your property. They do all the managment and take the honey, you get the advantage of pollination for your trees.  When we managed orchards in Nong Han, out behind MJU, this worked out very good for us and our trees and yields. 

Thanks, I’ll ask around.