KNUDSON: CAMBIAL ACTIVITY 535 
OBSERVATIONS ON THE PEACH 
In studying cambial activity in the peach the methods employed 
were essentially the same as for the grape. Three peach trees 
were used, all growing under apparently identical conditions on 
the grounds of Cornell University. The trees were of the variety 
known as Wakefield and they were probably fifteen years of age. 
They had produced a good crop of fruit during the preceding season, 
and the same held true for the year when the observations were 
made. Cuttings were taken of one-year-old, five-year-old, and ten- 
year-old branches, the branches being respectively of approxi- 
mately the same exposure and the same diameter. The detailed 
data follow in TABLE II. 
TABLE II 
AVERAGE DIAMETER INCREASE IN THE PEACH 
One-year-old Five-year-old tere 
Bite ot branches branches | anches ‘ 
cutting - | General notes on growth 
“Xylem — Xylem Phloem | Xylem | Phloem | 
A aN : | 
2 | 
May 8..| 61.5 a 112. 92.2! 287 | 102 |Buds just opening 
PO RS. OLS | | 49.| 153 | 82 184 | 102 \Leaves4cm.long. Late 
Fa looming period 
23 143 II4 143 | 120 205 102 9c ew 
we shoots 2 or 3 cm. in length 
ao oe _ 225 | 123 307 | 123 |Leaves 9 cm. long, full- 
. New shoot 6 cm. 
Fruit 20 X10 X12 mm. 
Jans 7..| 174 OA) east 220 410 | 266 |New shoot long. Fruit 
| 22 X25 X33 m 
ee ae — 246 | 164 512 | 307 New buds evident. Fruit 
- : 27 X30 X36 mm. 
20.,| 266 116: | 205° | 153 584 | 320 Fruit 38X30xX28 m 
ys Stone just wri ea 
29-.| 95 69 250 | 205 500 | 287 (Fruit 40X35 X30 m 
July 19.. dos 166 75 205 | 164 492 | 307 (Fruit just beginning re ripen 
Aug. 9. 145.9| 75 | 266 | 164 389 | 205 
An examination of the table reveals the fact that cambial 
activity began in the peach at the time of the opening of the buds. 
This is contrary to the condition found in the larch, grape, and 
apple. Complete differentiation of the new xylem was evident 
by July 19, when the cambium layer appeared to be in a resting 
condition. It is not possible to draw conclusions regarding the 
Period of greatest cambial activity, since the variation in growth in 
the different branches is apparently considerable. 
