New Citrus Creations 1904
by Herbert J. Webber & Walter T. Swingle, U.S. Dept. of Agriculture
Production of Hardy Citrus Fruits
The citrus industry in Florida has frequently suffered from severe freezes. The most disastrous of these probably were the freezes of 1835, 1886, and 1894- 95, which killed or seriously injured almost every tree in the State. Other minor freezes have occurred from time to time, which, while not so severe, have seriously damaged many orange groves. In California and Arizona, also, citrus trees are frequently injured by severe cold. It is thus clear that the most desirable improvement in the orange and other citrus fruits is the securing of varieties which can endure lower degrees of temperature and which may be grown throughout the present orange-producing sections without danger of injury by cold.
In attempting to improve citrus fruits in hardiness, two methods present themselves. One method would be to grow a large number of seedlings and select from them the individuals which possess the greatest degree of hardiness, and continue this selection throughout numerous generations in the hope of augmenting any greater degree of hardiness that might be discovered. To pursue this policy with citrus fruits would require so long a period to secure any marked results that the method is impracticable. This is shown by the fact that for many years citrus growers have been making selections based on the hardiness of seedlings, and as yet no appreciable advance has been made in this direction.
A second method would be to select some hardy wild or cultivated type and cross this with the sweet orange or lemon in the hope of obtaining good varieties, combining the hardiness of one with the good fruit quality of the other. If such a hardy type exists, this method would certainly seem to be the quickest and most practicable way of securing hardy varieties. A species of citrus known as the trifoliate orange (Citrus trifoliata) is such a hardy type, which can be grown without protection as far north as Philadelphia.
The common variety of the trifoliate orange was introduced into this country by the late William Saunders, of the Department of Agriculture, in 1869. The tree is small and bushy and very spiny, and the leaves are trifoliolate and deciduous. It is quite commonly grown as a lawn tree in the North and as a hedge plant in the South, while in the colder sections of Florida it is used as a hardy stock on which to bud the common orange and other citrus fruits.
The rind, which adheres tightly, is about one-sixteenth inch in thickness. The pulp is acrid, bitter, and gummy, and the enormous number of seeds leave little room for pulp. The fruit is thus worthless as far as edible qualities are concerned. It is highly aromatic and attractive in appearance, making the plant desirable for ornamental purposes. Its hardy character, however, is the factor of importance in connection with the experiments in the production of a hardy orange.
The increase in vigor which is commonly exhibited by hybrids between distinct parents is clearly shown by hybrids between the trifoliate and the common orange. Those which have intermediate characters, showing that they are true hybrids, are almost invariably much more vigorous than the seedlings of either parent.
The Citrange, a New Group of Citrus Fruits
In the course of these experiments two fruits have been produced which are hybrids between the common sweet orange and the trifoliate orange, and which promise to be of considerable value. They lie about midway between the two parents, but are not sweet oranges, trifoliate oranges, nor lemons, and are totally different from any other group of citrus fruits. It therefore becomes necessary to refer these hybrids to a new group of citrus fruits, and it is proposed to call them ‘citranges,’ a term made up of the first syllable of the word citrus and the last syllable of the word orange. The two varieties which are to be referred to this group are described in detail on page 56.
The Tangelo, a New Group of Loose-Skinned Citrus Fruits
During the course of these experiments a hybrid has been produced between the pomelo and tangerine which occupies a position intermediate between these two well-known fruits. It is neither a pomelo nor a tangerine, but is different and unique and bids fair to take a place by itself. The fruit is intermediate in size between the two parental varieties, has the easily removable rind of the tangerine, and in flavor is somewhat sweeter than the pomelo, with less bitterness. It is distinct from any of the various groups of citrus fruits and should, therefore, be referred to a new group. The term ‘tangelo’ is suggested by the writers as a name for this group of loose-skinned fruits, which lie midway between the pomelo and tangerine, the word being a combination of the first syllable of the word tangerine, with the ending of the word pomelo. A variety of citrus fruits known as the ‘nocatee,’ which has already been described and introduced, is apparently somewhat similar to this fruit and is evidently a hybrid between the tangerine and pomelo. This and the new Sampson tangelo, which is described on the previous page, are at present the only two varieties that can be referred to the tangelo group.
New Tangerine Oranges
One of the primary objects in the citrus breeding experiments was to produce hybrids between the common sweet orange and tangerine in order to secure a new fruit having the size, quality, and flavor of the ordinary orange combined with the loose, easily removable rind of the tangerine. A few of these hybrids have now fruited, and two of them, crosses of the Dancey tangerine with pollen of the Parson Brown orange, have produced fruits which are of considerable value. Both of these seedlings were grown from one fruit which was the result of a cross made in the grove of Mr. W.K. Trimble, of Braidentown, Fla. While the fruits were supposed to be hybrids, they nevertheless resemble the tangerine orange in all important characters, differing from the Dancey tangerine, which was used as the mother parent, mainly in being larger and considerably earlier in time of maturity and in being of rather better quality.