This section is from "The Horticulturist, And Journal Of Rural Art And Rural Taste", by P. Barry, A. J. Downing, J. Jay Smith, Peter B. Mead, F. W. Woodward, Henry T. Williams. Also available from Amazon: Horticulturist and Journal of Rural Art and Rural Taste.
Mr. Dowing: - There are some peculiarities belonging to blue flowers which I have not noticed to have been observed by others, or if observed, I do not recollect to have seen them published. Should you think the following remarks sufficiently interesting, they are at your service. One of those peculiar traits, is, that a large majority of our native plants bearing blue flowers, bloom either early in the spring months or late in the autumn or fall months. Let any one take the trouble to make out a list of the flowers as they begin to bloom in the months of March or April, as the locality north or south will require, and continue it through the summer and fall to November, he will be surprised at the large number of blue flowers in the spring and autumn months, and the small proportion, relative than those of other colon? We see that whenever we bruise the petals or express the juice from the petals of red flowers, and expose it to the atmosphere, it changes to a blue color; is this change of color caused by the absorption of oxygen? If so, may not plants consume a greater quantity at the seasons above alluded to, than when in a more rarifled state? Or does the intensity of the solar rays alone cause a redundancy of the brighter colored flowers during the summer months.
Another peculiarity is, that blue flowering plants in their native state, are much more frequently found growing in moist shaded situations, than in more exposed or sunny spots. There are several plants whose color can be changed from pale red to blue, by employing swamp mould, and keeping them in the shade, more especially among those that bloom early in the spring. By pursuing the hints thus thrown out by the Creator, can we not be led to try the experiment of producing blue flowers upon plants that now uniformly bear those of other colors. Probably they would require to be carried through several generations before their present habits would give way to this artificial treatment. I have very little doubt of success if the experiments were persevered in.
The peculiarities are so palpable and distinct, that if upon experiment the foregoing suggestions should be found to be true either in whole or part, by any person who may have more leisure than your humble servant to try them, I shall be amply repaid for the time employed in writing this fugitive article. J. Van Buren. Clarksville, Geo., Oct. 17,1861.