I am trying to develop new varieties of Japanese Maple (Acer palmatum) which thrive in the heat, humidity, and drought of the Southeastern US. I started this project last fall and have a few promising candidates from last year's crop. This fall I collected as many seeds as I could from various sources and plan to grow literally thousands of seedlings next spring to select from. I am focusing on collecting seeds from mature trees that have thrived in full sun in the heat of the south (I am in Atlanta GA which is zone 7b). Unfortunately I am only one man and my range of collection is limited to my local area. I currently have a large stash of seeds, but I need to diversify my sources. I would be willing to trade seeds with others who can provide seeds from mature trees that have thrived in hot climates. I would also be willing to purchase seeds if you are not interested in a trade. It would be great to get some seeds from mature trees in regions hotter than my own, such as south Georgia, Louisiana, Texas, Florida, etc. Please contact me if you would like to help out with this project.
This is a little off topic, but I wanted to share an experience I have with a heat tolerant Japanese maples that you may, or may not, find useful for your project. This summer we were hit with one of the worst droughts since 1988. The summer was extremely hot and dry. When visiting a nursery that has 100's of mature specimen Japanese maples at the end of the summer, it was very sad to see all the devastated Japanese maples, from a summer of extreme heat. The nursery’s large watering lake was about 85% empty that feeds their drip irrigation system, which in all other years keeps their maples thriving. Many trees lost their leaves by August and others were 75% bare with heavy damage to the remaining leaves. Out of all the devastation stood Acer shirasawanum 'Palmatifolium'. It was thriving in all the heat and looked beautiful. No scorch or damage to ANY of the leaves. If this tree is not on your radar, you may want to consider researching it further for your project.
Thanks JT1, I appreciate your reply. I have only been working on Acer palmatum so far because of the high variability, but it sounds like Acer shirasawanum 'Palmatifolium' is worth looking into. Thanks again.
Palmatifolium is practically indestructible... It's been described as the Japanese Maple for people who can't grow Japanese Maples! :) When I bought mine it was damaged in shipping, only a little bit of the scion was left, the rest broke off. I expected it to die, but it's grown into a very attractive tree, never suffered even any die back.
I've only seen a few cultivars of Acer shirasawanum available, so it concerns me that the variability of this species is not very high. Without much variability the likelyhood is low of coming up with a significantly different enough seedling to warrant the perpetuation of a new cultivar. Perhaps it would be worth trying to hybridize Acer s. "Palmatifolium" with proven palmatum cultivars to create new desirable hot climate cultivars? Has anyone here purposefully tried this hybridization? I remember reading about the extremely variable leaf shapes these kinds of hybrids can produce in Vertrees, but not much more info than that. Which palmatum cultivars are considered the most heat tolerant and would make a good candidate for hybridization with Acer s. "Palmatifolium"? The consensus at the nurseries in the southeast seems to be that Bloodgood is the most tolerant of sun in the hot climates.
Shirasawanum and Palmatum do hybridize easily, there are some well known cultivars around, e.g. Yasmin. I don't personally have experience of Palmatifolium being heat resistant (since I don't live in a hot climate) just that it's tough. I vaguely remember a heat resistant cultivar out of one of the Georgia (I think) research stations some time ago, but I can't find the reference.
Emery, you may be referring to Acer palmatum 'Glowing Embers'. It's an introduction out of Georgia known for its heat tolerance. DougieMapleSeed, if this is the tree that Emery mentions and you are interested in researching it further. Be sure that you are looking for the right Glowing Embers. There are 2 very different varieties out there with the same name. One is the green leaf variety from Georgia, which is known for heat tolerance. The other is a red leaf cultivar from British Columbia. If you find someone who says they have it make sure it's the right one. The one from Georgia is the newer introduction.
Thanks for your input Emery and John. I actually have a Glowing Embers of the Georgia variety in my collection, but I've only had it for one growing season so far and it did not produce seeds last year. Glowing Embers is rather unremarkable for most of the year compared to many of the other cultivars (large upright green palmate), but I suppose its proven heat resistance and fall color would make it a good candidate for my project. I will hand pollinate it next year if it sets flowers for me. I would like to produce a variety with more appealing leaf color and shape, but with the vigor and heat tolerance of Glowing Embers. Any suggestions for which cultivars to use as pollen sources? For the most part I will just be germinating a large number of open pollinated seeds from heat tolerant sources, but it would be nice to try my hand at some hand pollination of purposeful crosses. I will be selecting seedlings primarily on vigor and desirable phenotype all the while letting the harsh environmental conditions select for heat resistance.
If you look at their native range, acer palmatum should be the most heat+humidity resistant, then comes acer shirasawanum. Acer amoenum grows both in warm and cold areas while acer japonicum and acer amoenum var. matsumurae are the least heat tolerant of the species normally referred to as 'Japanese' Maples. One would assume that the cultivars of those species also follow the trend. Otherwise if you do a search in this forum with the keywords Houston and/or Nelran you will learn which cultivars do well there. Gomero
