Koishikawa Botanical Garden, the historical botanical gardens in Tokyo

Almost ten years ago, I went to Koishikawa Botanical Garden in Bunkyo, Tokyo on my second trip to Tokyo.
The place is located in a residential quarter.
Currently the garden is maintained by Tokyo university but originally it was made by Tokugawa shogunate in 1684 as "Koishikawa oyaku en (Koishikawa medicinal herb garden)".
They did tests for cultivation techniques, and have grown various plant species.

I went to there because I wanted to see the site of trial rearing of sweet potato by Aoki Konyo.
Aoki Konyo was a scholar and he have known the knowledge of Dutch or western sciences.
He accomplished a cultivation of sweet potato in the place, and later his sweet potatoes saved Japanese people at the times of famine.
I saw the site.
There was a quiet place and I felt relaxed.

Besides that, there are interesting plants and gardens there.
One of them is "Newton's apple tree".
Probably you know the famous anecdote of the apple.
That is about the apple tree that made Isaac Newton getting the idea of the law of universal gravitation.
In Koishikawa Botanical Garden you can see the one of graft of the tree.

Unfortunately, when I went to there, the tree didn't have any apples.
Still the old tree can have fruit, but they say it's apple is small and not so tasty.
I want to try it a little if I can have it someday.