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Darwin Correspondence Project

From E. L. Sturtevant   12 January 1878

So Framingham, Mass.

Jan. 12. 1878.

Charles Darwin, F.R.S. etc.

Dear Sir;

Having occasion to refer to your account of maize, in preparing an article on the plant, it occurred that a communication from one who has made the plant a study might be of service to you.1

Please accept the enclosed. If useful, well! If simply a trespass on you, then you can readily dispose of it in your waste basket.

Very truly | E Lewis Sturtevant


The maize plant appears to be one of the most plastic of our agricultural growings, and its variations seem scarcely to have received the attention that they deserve. As I have made rather of a special study of this plant, a few particulars may not be uninteresting, not derived from books, but from my own observation.

The only classification which I can offer at present is into sweet corn, field corn and pop corn.2 Sweet corn is distinguished by the glucose it contains in the seed and the plant, and in the shrivelled or wrinkled condition of the mature seeds. It varies in color from lemon yellow (white when immature), a pinkish shade, and a purple, to black. I have never seen it yellow, as we call field corn yellow. The corn is translucent at the edges. The uses of sweet corn are mainly as a vegetable. Field corn includes the varieties which are cultivated as farm crops for the mature seed, which is used for feeding in its dry state and as mealed; in commerce as corn flour, corn starch, meal, samp and hominies &c. It varies in the size and shape of its kernel, as well as in the texture of the kernel. In color it may be white, lemon yellow, bright yellow, red, purple, and striped. This species admits of subdivision into flint and dent varieties, the border lines not being very well defined, and varieties which are neither flint nor dented. Field corn always presents in a section of its kernel a distinct, usually large nucleus of starch about the chit, and in the flint varieties surrounded, in the dent varieties enclosed at the sides only, by a horny or corneous covering. Pop corn is a flint corn, but the oil is distributed throughout the mass in such a manner that in the best varieties a section shows the whole substance to be corneous except the merest line of starch at the chit. When this corn is gradually brought to the temperature that decomposing the oil causes the tension to be overcome, the kernel explodes into a large, tender, crisp bulky product of showy whiteness. The shapes and colors of pop corn are extremely various, but it is always small eared and small kernelled, and of a small habit of growth.

I have never known sweet corn to change into field or pop corn, but pop corn under high culture will in a few years change its character, and increase its size. The rice or peaked kernel will change to the rounded kernel and more rarely vice-versa. Flint corn will change, either through climatic, cultural or selective influence, into dent corn, and vice versa, and it requires but little care to change one variety into a so-called different variety. From experience I can state that three years selection is sufficient to change the average length of cob, the grouping of the grain, the shape of the ear, and the habit of growth, and so strong is the tendency of the product to vary, that it is difficult to suppose any limitation to the changes which would follow any well organized effort.

In every field of considerable size, monstrosities are frequent. The occurrence of females flowers, which develop into perfect grain, on the plume, amidst the male flowers, is very frequent.3 More rarely, yet still always to be found, the male flowers develop on the cob in conjunction with the ovaries, more usually as a prolongation of the cob growth, yet not very rarely in juxta position with the ovaries. I have specimens on my shelves of all these cases, as well as of double and triple ears in the normal position. The flint corn, the Waushakum variety,4 such as I grow, develops its uppermost ear normally on the fifth node from the bottom, yet I have known the ear to be found on the first even, and so up to the sixth in exceptional cases. I have one specimen preserved where four ears have formed on the uppermost node just below the tassel. Occasionally the corn plant will branch, and the branch bear a terminal ear. By intervention the cob can be forced at times into development into a spike crowned by the tassel, and an obstruction to the length-growth will frequently cause the grain to become spirally arranged on the cob. At the appearance of the tassel, a dissection will show a small ear, perfect in its parts, upon which by means of a hand magnifier each ovary can be counted, situate at each of the five lower nodes. If the stalk be cut away carefully now, in many instances—in all I have tried—the upper embryo ear ceases to develop and a tassel stalk occupies ultimately the position where we would normally look for the ear.

In every instance I have seen, the number of rows of kernel on the cob have been divisible by two. I have seen two rowed corn, 4 rowed, and so on up to 36 rows. One specimen at the Smithsonian Institution at Washington, taken from a grave at Arequipa, Peru, contains 13 rows, and this is the only exception I have heard of.

The length of ears vary from 2 inches to 15 inches. I have seen pop corn two feet high, and ears from 112 to 2 inches long, and a dent corn thirteen feet high with ears 12 inches long, grown on the same field by the same culture. In Tennesse it is stated a stalk was once measured 22 feet 3 inches high. On my farm in Massachusetts I often find corn ten and twelve feet high. Some ears of pop corn are nearly circular, so great is the disproportion between the length and the diameter; other ears are long and slim. The cob varies much in proportion to the corn, and as well in its density.

In our northern corn, the normal shape of the kernel is globular, but it takes on a flattened shape in the ear usually, through the pressure of adjoining kernels. Some of the dent varieties grown in Connecticutt have a kernel resembling a horses tooth, other varieties have a flattened kernel, in others the kernel is produced into a sharp tooth which may even be recurved. The sweet corn has always greatly wrinkled kernels, etc. etc.

The proportion of the leaf to the grain varies also very largely, being influenced by the season, by the culture, and by the habit of growth of the variety planted. In the ordinary or dry state, this variation may be 1 lb. of grain and 34 lb. of straw and 1 lb. of grain and 2–3 lbs. of straw for prolific fields, and when there is a small yield there is no setting the limit.

The usual crop with me is about 75 bushels of shelled grain, 56 lbs. to the bushel per acre, but 100 bushels on some acres is not an exceptional yield, and I have even attained at the rate of 123. In one experimental trial I raised 23 ears from one kernel, and in another instance when I counted the kernels I found 3368. This was northern corn. The largest number of kernels in a line I have counted has been 69, and this was an 8-rowed variety. The number of kernels in a row appears to be a variety peculiarity, while the length of the ear seems to be determined in part at least by the expansion of the kernels, but it is difficult to draw conclusions of this nature until a variety has become very uniform through a vigorous course of selection.

I could readily quote authorities and statements concerning corn, which would extend the limits I have here mentioned, but I have preferred to keep mainly to my own experience.5

Very truly | E. Lewis Sturtevant

Waushakum Farm | So Framingham, Mass. | Jan. 12. 1878

CD annotations

Top of enclosure: ‘Curious difference in the condition of the seeds’ pencil


CD discussed maize (Zea mays) in Variation 2d ed., pp. 338–41 and passim.
Sweetcorn: Zea mays var. saccharata or rugosa. Field corn: Zea mays var. indentata. Popcorn: Zea mays var. everta.
Sexual change in flowers in maize had been observed by John Scott; see Correspondence vol. 12, letter from John Scott, 7 January [1864]. See also Mangelsdorf 1974.
Sturtevant developed the Waushakum variety of corn himself (DAB).
Sturtevant presented a paper, ‘Indian corn’, at the annual meeting of the New York State Agricultural Society on 22 January 1879 (Sturtevant 1879); there is a very lightly annotated offprint in the Darwin Pamphlet Collection–CUL. He gave a bibliography on page 5.


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

DAB: Dictionary of American biography. Under the auspices of the American Council of Learned Societies. 20 vols., index, and 10 supplements. New York: Charles Scribner’s Sons; Simon & Schuster Macmillan. London: Oxford University Press; Humphrey Milford. 1928–95.

Mangelsdorf, Paul C. 1974. Corn. Its origin, evolution, and improvement. Cambridge, Mass.: Belknap Press of Harvard University Press.

Sturtevant, Edward Lewis. 1879. Indian corn. [Read 22 January 1879.] Transactions of the New York State Agricultural Society 33 (1877–82): 37–73.

Variation 2d ed.: The variation of animals and plants under domestication. By Charles Darwin. 2d edition. 2 vols. London: John Murray. 1875.


Encloses some notes on maize that may be useful.

Letter details

Letter no.
Edward Lewis Sturtevant
Charles Robert Darwin
Sent from
Framingham, Mass.
Source of text
DAR 177: 269
Physical description
ALS 1p, encl AmemS 3pp †

Please cite as

Darwin Correspondence Project, “Letter no. 11320,” accessed on 21 June 2024,