gergweber - Thanks for the links.
Mac- some disconnected thoughts for you.
It is definitely true that the scion will not change sex when grafted onto rootstock of a different sex. This is a common practice in fruit orchards for fruit trees with separate sexes or self incompatible for pollination. Perhaps you remember the 5 on 1 trunk apple trees offered by outfits like Starks or Burpee. Root stock chosen will determine tree size, there are dwarfing root stocks to keep apple trees small. Understock does change some characteristics of the scion wood. Growth rate and size may be a function of the size and vigor of the root stock.
The only holly I have seen with a male branch grafted onto a female the graft was still young and had not healed yet, but it appeared to work. No reason not to graft a branch onto holly. Most though just keep a male shrub tucked away somewhere in the neighborhood. Bees do the work. One male can pollinate a dozen or so females.
About persimmons. They have separate sexes. Many female cultivars will form seedless fruit if there is no pollinator. The flavor of seedless fruit is not as good, less complex. The relatively bland flavor of the seedless grocery store persimmon (D. kaki) is because of this phenomena. Persimmon can be successfully grafted, so no reason to not try if you have scion wood that you want to graft onto a persimmon. I personally would just keep separate trees. One male can pollinate up to a dozen females if you have either active bees or an active artist's paint brush or cotton swab. From seed, persimmon start blooming when grown in the ground, as early as 6 or 7 years, most take about 9 years, in a pot it can take considerably longer. Persimmons can be rooted from cuttings, so cuttings and air layers are possible.
Ginkgo, in China, they will frequently graft one male branch on every female tree being used for nut production.
With all grafting, it takes some practice and some good luck to get a graft that will heal smooth enough to be acceptable for bonsai. While a graft will 'take' within a few months, it takes at least three years before there is enough wood that you can treat the tree like a 'normal' tree. Be cautious about bumping or flexing a grafted on branch, the stress on a young, weak graft union can cause separation. A bonsai tree will be "out of commission" for several years while graft unions heal.
When cultivars with different growth rates are grafted, there can be swelling issues. Sometimes the graft union just never smooths out. This is why as a general rule grafted stock is avoided by the bonsai hobby. Sometimes the understock imparts vigor to the scion wood, roots of JBP are able to handle warm soils better than the roots of JWP. A grafted JWP on JBP rootstock will have stiffer needles and sometimes a faster growth rate than when grown on its own roots, so heat tolerance and quicker growth are why most JWP are grafted.
Those are my thoughts. I have done about a dozen grafts, and as a novice, I am running about 30% successful. My best success was bud grafting 5 buds of a nice flowered weeping crab apple onto a 3 inch diameter stump/trunk of common grafting under stock for orchard apples. Made it to year 4, the unions are firm enough now that I can really start work on it this spring. It takes practice.
Good luck.
sorry couldn't resist would like to know as well
