HYBRIDS OF JUGLANS. 43 



califomica - Juglans nigra, Nos. 1 and 2, were both about 1.5 meters 

 high; the smallest of this eross, Nos. 3 and 4, were 40 and 50 cm. high, 

 respectively. The largest specimens of Juglans calif arnica X Juglans rcgia, 

 Nos. A and B, were from 3 to 4 meters Irish; and the smallest, Nos. C and 

 D, were 70 and 150 cm. high, respectively. All of the second-generation 

 plants of either race were of the same age and were apparently growing 

 under similar conditions. 



Leaves of the Hybrids. 



Fully developed leaves, taken from analogous portions of the plants, were 

 examined and the basal pair of leaflets were photographed (plates 9 and 

 10). Plate 9 shows the basal leaflets of 4 leaves of plant No. 4, Juglans 

 califomica < Juglans nigra. No. 1 of the figure had 10 leaflets and was 18 

 cm. long; No. 2 had 11 leaflets and was 29 cm. long; No. 3 had 11 leaflets 

 and was 21 cm. long; and No. 4 had 11 leaflets and was 26.5 cm. in length. 

 Plate 9 shows, also, the basal leaflets of leaves from plant No. 1. Of the fig- 

 ure, No. 1 is of a leaf which was 40 cm. long and had 18 leaflets; No. 2 had 

 17 leaflets and was 34 cm. in length; No. 3 is of a leaf which had 17 leaflets 

 also and was 36 cm. long; and No. 4 is of a leaf which bore 13 leaflets 

 and was 25 cm. in length. Plate 10, lower figure, is of the basal leaflets of 

 plant No. A, Juglans califomica X Juglans regia. Of the figure, No. 1 is of 

 a leaf which bore 11 leaflets and was 49.5 cm. long; No. 2 is of a leaf which 

 bore 9 leaflets and was 51 cm. long; No. 3 is of a leaf which had 7 leaflets and 

 was 25 cm. long; and No. 4 is of a leaf which had 11 leaflets and which was 

 55.5 cm. in length. Plate 10, upper figure, is of the basal leaflets of leaves 

 from plant No. C. No. 1 is from a leaf which bore 9 leaflets and which was 

 34.5 cm. long; No. 2 is of a leaf which had 7 leaflets and was 25 cm. in 

 length; No. 3 is of a leaf which bore 8 leaflets and measured 32.5 cm. in 

 length; and No. 4 is of a leaf which had 8 leaflets and which was 26 cm. in 

 length. The leaves and leaflets of D, which are not shown, were very 

 large, so that only two leaf-bases could be accommodated on the photo- 

 graphic screen at one time. One leaf of D had 12 leaflets and was 37.5 cm. 

 long; and another had 15 leaflets and was 66.5 cm. in length. 



There is thus a considerable variation in both series in size of leaves 

 and in number of leaflets, both as regards those of a single individual 

 and those from different plants of the same blood. As for other char- 

 acters, such as form of leaflet, shape of apex and of base, emargination, 

 and texture or character of surface, there is less variation between the 

 leaves of any individual than between the leaves from different plants. 

 From the examination the following generalizations seem to hold: (l) 

 The largest leaves have also the greatest number of leaflets; (2) the largest 

 leaves are most variable as regards the number of component leaflets. The 

 converse of these is true for the smaller leaves. Except for plant D, also, 

 the largest leaves are borne upon the largest plants; that is, the leaves ap- 

 pear to be an index of the vigor of the plants. The number of leaflets of 



