8 



LIMITATION OF SATSUMA GRANGE. 



In case the soil is not adapted to the Trifoliate orange, there is 

 little hope of gro^^^ng the Satsuma orange successfully unless some 

 new stock not as yet known is found adapted to this 

 variety and able to grow on light soils. As a last 

 resort, grapefruit, citrange,'^ or some other stock could 

 be tested, but it is useless to set out trees of this variety 

 grafted on sour-orange stocks. 



HOW TO DISTINGUISH TRIFOLIATE FROM SOUR- 

 ORANGE STOCK. 



In 1887, Prof. Otto Penzig, director of the botanic 

 garden at Genoa, Italy, published a very interesting 

 account of citrus fruits for the Department of Agri- 

 culture, Industry, and Commerce 

 of the Italian Government. In the 

 course of his investigations of the 

 anatomy of the principal types 

 of citrus fruits, he discovered a 

 striking difference in the structure 

 of the pith of the Trifoliate orange 

 as compared with that of other 

 citrus fruits.'' 



If a section be made lengthwise 

 of a stem or twig of the Trifoliate 

 orange, the pith is found to con- 

 tain rows of cells arranged so as to 

 form more or less imperfect partitions some- 

 what like the partitions in the pith of the wal- 

 nut. Such a section of the Trifoliate orange 

 showing the cross plates of thick-walled cells 

 in the pith is shown in figure 4 to be contrasted 

 with figure 5, showing the absence of any such 

 plates in the pith of the sour orange. A few of the thick-walled 

 cells which make up the imperfect longitudinal cross partitions of the 

 Trifoliate orange are shown under higher magnification in figure 6. 



Fig. 4.— Longi- 

 tudinal section 

 of the pith of 

 the Trifoliate 

 orange, show- 

 ing the thick- 

 walled, pitted 

 cells that make 

 up the imper- 

 fect cross 

 plates. (Mag- 

 nified 56 diame- 

 ters.) (Drawn 

 by Dr. Theo. 

 Holm.) 



Fig. 5. — Longitudinal sec- 

 tion of the pith of the 

 sour orange. Note the 

 absence of any thick- 

 walled cells. (Magni- 

 fied 56 diameters.) 

 (Drawn by Dr. Theo. 

 Holm.) 



a The citrange is a hardy citrus fruit originated by the Department of Agriculture 

 by crossing the common orange and the Trifoliate orange. Citranges grow more vigor- 

 ously than either parent, and some varieties can be reproduced practically unchanged 

 from the numerous seeds. Because of their vigor and their being half orange, cit- 

 ranges can be expected to thrive in soils too light for the straight Trifoliate. As the 

 Satsuma orange grows rapidly on sweet-orange stock and fruits well on Trifoliate 

 Btock, it would probably succeed on the citrange, a hybrid of these two stocks. 



b Penzig, O. Studi botanici sugli agrumi e suUe piante affine, in Annali di Agricol- 

 tura, 1887, p. 137, pi. 13, fig. 6 (Ministero di Agricoltura, ludustria e Commercio). 

 Rome, 1887. 

 [Cir. 46] 



