Autumn Colors (Sep.17,1935) It is popularly thought that California has "no autumn colors" because "it doesn't get cold enough", and that such colors are, where found, a result of frost. It is true that, in the more thickly settled portions which are naturally those regions of moderate elevation, there is not the vivid autumnal coloration seen in colder climates and at higher el- evations, even in California. The principal reasons for this absence appear to be two in number: First: The scarcity of deciduous trees of the kind which, elsewhere, are common and take on brilliant color before the leaves fall. Second: Deficiency of soil moisture during the late summer months which checks growth of leaves and causes them dry up without undergoing the chemical changes incident to the production of color. Where deciduous trees, such as maples, for example, have been planted or are indigenous, along streams or where they get ample supplies of moisture, autumn coloration is not inferior to that found elsewhere. Frost has nothing to do with it. Thus at this place, the Boston ivy (Ampelopsis Veitchii) is now brilliant on walls where the plant has had sufficient moisture, but not too much, and not too much sun, and fully green on walls where the plant has had enough water to keep it in active growth. Frost has never been known here in September. Where there is too much sun and too little water, the leaves dry up and fall without turning. Where there is a slight deficiency in moisture and not too much sun, the leaves color earlier, but brilliantly. Where there is an abundance of moisture and not too much sun the leaves are green still. A plant on the north wall may be brilliantly colored, but all leaves of that same plant where the branches have gone around a corner and are on an east wall may be green. Where these branches continue onward and again spread out on a north wall (the same plant) there may be an abrupt change from green to autumn colors abruptly at the corner. An actual case here. There is another plant here, with slightly deficient water supply that is fully colored on the north wall, just beginning to turn on the east wall and nearly fully colored on a partially shaded south wall. (On south walls it hunts for shade). Another one growing at the base of a south wall has green leaves on the east wall (partially shaded), also under the south eaves, but where exposed to the full sun on the south wall (which it is trying to avoid, the leaves, while still green, are beginning to show signs of passing directly to the dry stage. Another growing at the base of a north wall with plentiful water supply, is wholly green on north and east walls (the only walls upon which it spreads). A Japanese maple here in partial shade was experimented on. It is at present entirely green. Formerly its leaves turned brown and fell without coloring. I found that, if given sufficient moisture, it will color splendidly.