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of the rachi forms the cob. It is interesting to observe that the development of the cob seems to be in some measure de
adaptation to the locality in which it is grown.1
In the cultivated varieties the glumes and paleae are reduced to small membranous parts around the base of the grains. In the pod maize, however, the glumes are very large, completely enclosing the grains.
The several rachi which make up the cob usually grow nearly straight from butt to tip; hence the two-ranked spikelets result in grains being usually arranged in regular order. These pairs of ovularies are fertilized with such certainty that under normal conditions an odd number of rows never results. Even where the number of rows is less at the tip end than at the butt, the number of rows remains even,—the reduction in number is made by the omission of a piece of the rachis. The case of an ear having twenty-one rows has been reported,2 but if authentic, is certainly a very rare instance.
218. The Position of the Ear.—The position of the ear on the culm (stalk) varies more widely than does the ratio of grain to stover. In some varieties the ears may be too high or too low to be easily husked. When too high, the stalks are more easily blown down. Four feet above ground is a desirable height for ears of medium sized varieties. The shank by which
'Torrey Bui. 21, No. 12 (1894), p. 514.
t Trans. Mass. Soc. Prom. Agr. 1858, p. 114
each ear is attached to the main culm varies in length. The shorter length, holding the ear in position more firmly, is generally accompanied with a more compact husk, thus better protecting the ear from weather or the attacks of birds and insects. In sections where damage is liable to occur from excessive rainfall, the tip of the ear should hang downward. In the Southern States, if the tip of the ear points upward, rain will enter between the husk and ear and being held there a few warm days will cause the grain at the butt to sprout or rot .
219. Characteristics of Ear.—The physical characters of an ear of maize may, in some measure, indicate the yield, maturity, keeping quality and vitality, as well as its purity or trueness to type. By an examination of the split grain some indication of the composition may be obtained. (258) As in all plants and animals, however, the hereditary or reproductive power of ears of similar outward appearance may differ widely. (43) This is especially tr;ue of maize, since being wind pollenized, the male parent is unknown. The physical development of the ear is greatly influenced also by its environment.
220. Terms Descriptive Of Ear.—Grains are usually of the same character throughout the ear, or unikernelled, but in case of crosses between two types may have two forms or be bikernelled. A bikernelled variety from Chile has been figured by Bonafous.
The ear may be cylindrical or cylindraceous, cylindrical for a portion of Its length; tapering, distinctly tapering or slowly tapering, representing different degrees of decrease in diameter from butt to tip. In some varieties the ears are long and slender; in others short and thick; or the ear may be flat.
The grains may be even at butt with plane line of cob; or may be shallow rounded, moderately rounded or deeply rounded at the butt.
The ear may taper toward the butt through a flattening of the grains as if pressed down from above, depressed at bull, or through a decrease in the diameter of the cob, compressed at butt; or through a shortening of the length of grains, depressed-rounded at butt; or through both a shortening of the grain and a decrease in the cob, depressed-compressed at butt. Or the ear may be enlarged at butt by a more or less openness between rows; or expanded at butt through increase in number of rows. When space between pairs of rows extends to cob, it is open at butt. In some cases of eight or less rowed varieties the rows throughout the ear are in distinctly defined pairs, or distichous. The rows may be rectilinear, spiral or irregular.
The tip characters are quite variable within varieties, but a single terminal grain distinctly projecting is a character of decided permanence in the group of cap flints extensively grown in Connecticut and Rhode Island.
The furrows, or sulci, between rows may be absent, apparent, narrow, distinct, or very distinct.
Grains may be Jirm, loose or mosaic-like, when through pressure their edges become faceted. The grains may be at right angles to cob, upright; leaning forward, sloping, or may slope forward with apex slightly overlapping, imbricated.
The ear stalk may be nearly or quite the diameter of the cob, large, or about half the diameter of the cob, medium, or one-third the diameter or less, small. (243)
221. Two-Eared Varieties.—Under ordinary conditions of culture, and particularly with dent varieties, only one ear is produced on each stalk. In some types, as in pop and sweet varieties, the tendency to produce several ears is quite marked. The tendency is more marked in flint than in dent varieties in ordinary field culture. Bailey raised thirty-four ears from one seed of Zea canina,1 twenty-five being on the main stalk. Sturtevant has raised twenty-three ears from one grain of flint maize, and reports as claimed from twelve to nineteen ears per stalk in pop maize; ten or more in flint maize and six to fourteen in dent maize.
The thickness of planting, soil and season influence the number of ears per plant. By varying the number of grains per hill from one to five in the case of Waushakum flint maize, Sturtevant varied the number of ears from 4.6 to 1.2 per plant.
"Among the many varieties which have been tested at the station those which produce usually one ear to the stalk have given smaller yields than those which have produced a greater number of ears. It is quite possible, however, to increase the number of the ears at the expense of the total yield of grain. Three years ago a correspondent sent us a stalk bearing seven ears, and an accompanying letter offered a supply of the seed for twelve dollars a bushel. A workman was sent to one of the station fields with orders to bring the first five stalks he could find, each of which had two ears. Both lots were dried thoroughly before shelling, and in every case the grain from the stalks bearing two ears outweighed that from the seven-eared stalk. We have found no variety which produces uniformly one, two, or any other number of ears, but have found the ears to vary from 86 to 537 on one hundred stalks, counted as they stood in the rows. The best yields have come from those varieties which produce from 175 to 200 ears to one hundred stalks, and we have endeavored to find or to produce a variety which should have uniformly two ears on
I A variety of pop maize.
each stalk, as the nearer we have been able to approach such a variety, the greater has been the yield of grain per acre."1
No two-eared dent variety has ever been produced which has become extensively grown or widely popular. It has not been shown in what way it is easier for a stalk of maize to elaborate the material for two ears than it would be to produce the same grain in one ear. When harvested by hand, varieties bearing but one ear on a stalk are to be preferred, unless the two or more eared varieties yield an appreciably larger quantity of grain. On the other hand, when fed to cattle without removing from stalk, two smaller ears might be preferred. For silage, the total yield of grain would be the only consideration.
222. Barren Stalks.—A varying percentage of the stalks of the field are barren—do not bear any ears. The percentage of barren stalks on a given soil varies with the thickness of planting and the season. Barrenness does not seem to be a variety characteristic. It seems to be largely the result of environment . If it were an hereditary characteristic the fact that the stalks are barren would tend to eliminate them.
223. The Grain.—The maize grain has the same general structure as the wheat grain. (60) While quite variable, it is characterized by its large size as compared with the seed of any other species of the grass family. The weight of 100 grains may vary from three grams in Miniature pop to 100 grams in Cuzco soft.2 It is also greatly different in shape from the grain of the other cereals, the furrow on the side opposite the embryo being entirely wanting. In most varieties, the grain is flattened and more or less triangular or oval in shape with its lateral diameter greater than the diameter parallel with the axis of the cob, while some varieties have spheroidal and others conical grains.
Viewed from its broader surface, the grain may be broad above and taper by straight lines to a very narrow base, cuneale wedge-shaped; or may be broad above
1 Miss. Bui. 33 (1895), pp. 75-76.
IE.L Sturtevant: Varieties of Corn. U. S. Dept of Agr., Office of Expt. Sta. BuL S7, p. &
and taper by curved lines to a narrow base, rounded cuneate; or may be broad above, less broad below, connected by straight lines, truncaie-cutieaie; or sides of grain may be parallel in the upper portion and thence taper to a more or less broad base, shoe-peg form; or may be nearly or quite as broad at base as at summit, rectangular; or the corner may be rounded both above and below, rounded corners. The summit of the grain may be rounded or flat; may end in a long narrow tip, rostrate; or a short abrupt point, mucronate. On the other hand the summit of the grain may be depressed, dented. The indentation may be round or cup-shaped, dimple dented; or longer than broad, long dimple dented: or the sides may be pinched and parallel, crease dented; or the two sides may be pinched together closely and project upward and forward, pinched dented; or with the last condition there may be a more or less ragged projection from the summit on the side next the embryo, ligulate dented.
As a variety characteristic, depth is much more constant than width of grain, the former being a quite constant character.
224. Shape of Grain Upon Maturity.—Sturtevant states that each of the five types of maize furnishes three well-defined subtypes, with parallel relationship throughout. Thus, subtype A, the grain broader than deep; subtype B, the grain as broad as deep; subtype C, the grain much deeper than broad.
"All my «ollections concur towards the belief that climatic relations are more evident in these subspecies (subtypes) than in the species (types) themselves. With the possible exception of the dent corns and the starchy-sweet, for which as . yet but one locality is known, the climatic range and adaptability seem about the same, but in the subspecies (subtypes) there is diversity, A being for climates of short season, C for long seasons, while Bin general is intermediate; although a climate suitable for C can grow A and B." 2
In a study of 168 varieties, he classifies types and subtypes as follows: