Suckling. — Leaf-anatomy of Trees and Shrubs on Port Hills. 179 



logical tables at two neighbouring stations have been consulted, and these 

 will give a fair idea of conditions existing where the bush grows. These 

 two stations are in Christchurch City, and at the Convalescent Home on 

 the Port Hills, which is situated about 50 metres above sea-level. 



Rainfall in Christchurch throughout the year is, on the whole, fairly 



evenly distributed, but on an average most rain seems to fall in July. The 



mean rainfall for July for the years 1902-10, inclusive, was 7-820 cm. The 



rainfall each month seems to vary considerably for each year, sometimes 



one month being the wettest one year and perhaps the driest the next. 



The average annual rainfall is about 85 cm., or a little over. The number 



of days with rain seems to be more equal for each month than the actual 



rainfall. The mean total number of days with rain from 1902 to 1910 for 



the winter months (June, July, August) was 38-8 ; for September, October. 



and November, 29-5 ; for summer (December, January, February), 26-1 



lor autumn (March, April, May), 31-9. Comparison of records taken in 



Christchurch with those taken at the Convalescent Home shows that there 



is a considerable amount of difference in the two stations, and that there 



is some variation in relative amount of rainfall, that at Christchurch being 



sometimes less, sometimes more, than at the Home. For instance, in July, 



1910. the total rainfall for the month in Christchurch was 15-10 cm., while 



that on the hills was only 11 40 cm. Again, for August, 1907, Christchurch 



showed a total of 7-225 cm. ; the hills. 12-525 cm. On the whole, rainfall 



is rather less at the Convalescent Home than in the city, but is probably 



greater higher up the hill than it is at the foot. When an easterly wind is 



blowing, on a clear day, clouds often hang over the spurs of the hills. In 



summer, and sometimes in winter, dry hot north-westerly winds blowing 



against the northern slopes of the hills must affect the amount of moisture 



in the soil. 



Schimper* says that from an ecological point of view statistics as to 

 temperature should give the mean daily minimum and maximum for each 

 month of the year. These, however, are not available at the meteorological 

 stations referred to ; only the mean temperature for each month can be 

 given, as a rule. At Lincoln, a station south of Christchurch and some 

 few miles from the hills, the highest temperature recorded in 1903 was 

 83-8° F., in November ; the lowest, 22-0° F., in July. The temperature 

 for the different months does not differ so much in different years as does 

 the rainfall. The coldest months are from May to September, with an 

 average temperature of about 47° F. ; the hottest, from November to Feb- 

 ruary, with an average of about 59° F. 



The temperature readings at the Convalescent Home are not taken in 

 the same way as at the stations at Christchurch and Lincoln, and so are 

 of no value for comparison. However, readings have been taken by resi- 

 dents near the Home, and these show that the temperature is slightly higher 

 there than on the plains. There are fewer frosts near the foot of the hills 

 than in Christchurch, but it is probably colder higher up than it is nearer 

 the foot, for in winter snow often appears sooner near the top, and lies 

 longer. For instance, on the 20th September, 1911, there was snow lying 

 at the top, but none farther down. 



The only statistics for relative humidity, and force and frequency of 

 winds, are taken from Dr. Cockayne's paper on the Waimakariri River 



* Schimper, A. F. W. : " Plant Geography." Translated by W. R. Fisher. 1903 

 p. 175. 



