From "The Papers of Frederick Law Olmsted, Volume VI, The Johns Hopkins University Press (available in the Olmsted Society collection at the Riverside Public Library
Notes on Tree Grouping at Riverside
In planting the long common and adjoining borders, oaks and elms should frequently stand alone or a little detached from groups, more frequently alone than anywhere else on the place except perhaps Indian Garden where elms will be likely to grow particularly well and should accordingly be exhibited somewhat distinctively. In groups where oaks are intended to predominate, elms, especially the stiffer European sorts may be introduced. Chestnuts also associate very agreeably with nearly all oaks – better than with elms, so do the maples generally, and the maples better with chestnuts than with elms. The American Lime vary agreeably with either of the above. Dogwood and Alder and I should think the common Craetagus of Riverside would go well with oak and with all of the above. The English field Maple, A. Campestris is also harmonious with the oak in masses.
In groups in which the American elm predominates after other elms, maples may be subordinate with advantage. The Nettle tree and the Hornbeams are good for tailing down a group of elms being of lower growth and somewhat like form with but little variety of color. Ashes may also be planted with elm.
Ash with Black Walnut
Groups wholly of Ashes
Groups wholly of Beeches are very agreeable and alternate agreeably
Horn beam with Beech
Birches with Beech
Horn Beam with Birches
Consequently these three; though the little white birch is hardly suitable when you are studying broad effects with these.
American Lime may predominate in many groups. The Horse Chestnut associates more quietly with the Limes than with any other tree I think. I hardly know why and it may be more associative with other pleasant circumstances in my mind. I can put nothing else of much size agreeably with Massachusetts Maples – oaks – elms come in subordinately to bodies of Limes very pleasantly.
There are many varieties of the Limes: the silver leafed and the pendulous are very valuable on the ends of groups, or the lighter colored varieties in coves of the darker and vice versa. Do not feel wholly confident of the hardiness of the “fancy” varieties as they are all seedlings of the European.
The Mulberries may be planted with the Limes very freely I think.
I feel great confidence in the Larch upon the prairies and should therefore let it predominate in some groups – chiefly on the side issues of the Common – the Delaplaine road for example. Half a dozen larches might be associated with two or three Hemlocks, and as many Birches and Hornbeams. The little white Birch will be here appropriate, especially if you desire to tail down at the ends, the weeping larch and the weeping and cut-leaved birch will give elegance to the ends of such a group, or will appear to advantage standing alone nearby. Alder will come in also very well as a quite subordinate member and will serve to connect groups of Birch, Larch, etc., with adjoining groups of oaks, etc., with which it would (but they would not directly) harmonize.
The original is a typescript in the Olmsted Papers. Apparently prepared by Theodora Kimball, it bears the penciled notation “From manuscript notes of F.L.O.”