Otome zakura (Acer palmatum 'Otome zakura' )

Otome zakura is a member of the Corallinum group each of which has brilliant spring foliage, but the summer leaves are paler and more varied. The tree will grow fairly quickly to about 18′.

Oshu shidare (Acer palmatum 'Oshu shidare' )

This purple leaved tree is slightly pendulous growing up to 15′ high and wide, but slowly. Zone 5.

Osaka zuki (Acer palmatum 'Osaka zuki' )

This has been one of the most sought after Japanese Maples for over a century. It is known mostly for its shining crimson fall color, but it is generally a fine tree all year. The clean green leaves are broad and larger than most but never coarse looking. The tree develops reasonably quickly into a round-headed small tree to about 15′. zone 5

Orido nishiki (Acer palmatum 'Orido nishiki' )

The leaves are variegated with pink and white and so is the bark of the new limbs and twigs. Zone 5. The plant is excellently captured in this photo by Michael Healy.

Oregon Sunset (Acer palmatum 'Oregon Sunset' )

Oregon Sunset forms a small rounded soft-looking tree with excellent leaf color from spring (sweet red) to fall (sharp red). You can see from Michael Healy’s photo that the leaves droop down and in providing that cuddly look.

Orange Dream (Acer palmatum 'Orange Dream' )

Think ‘Katsura’ only better; or at least that is the word on the street; the largest ones I have seen are in my two gallon smart pots so I haven’t seen what they look like as large trees or even out in the sun, but I have noticed that they are sturdier and more vigorous than Katsura which are good things. The leaves also seem to have more red in them than Katsura, but I will have to see the shining halo in the afternoon sun all summer and fall to say it is as good as Katsura. This photo is from Michael Healy.

Omurayama (Acer palmatum 'Omurayama' )

Omuryama is an upright but spreading and somewhat pendulous head. It gets fairly tall for a palmatum (maybe 20′) and almost as wide; the fall color is stupendous, a sort of glowing orange red.

Omato (Acer palmatum 'Omato' )

Omato has my favorite leaf shape: broadly ovate lobes on good sized leaves. The spring color orange tinged; the summer color is green and the fall color is various reds. The tree can reach 24′ but is in no hurry to do it.

Olsen's Frosted Strawberry (Acer palmatum 'Olsen's Frosted Strawberry' )

Olsen’s is my new favorite palmatum. It is a pink reticulate, slow growing and spreading.

Okushimo (Acer palmatum 'Okushimo' )

Like Kurui jishi, Okushimo has curled-in leaves, but the tree is much narrower and taller (which is not saying much in terms of height (10′)), and the leaves are a light fresh green in the summer. Fall color is variable, gold to red.