2 
Indian Forest Records. 
[Vol. IV 
Disadvant¬ 
ages of exo¬ 
tics. 
Reports on 
exotics often 
untrust¬ 
worthy. 
Deteriora¬ 
tion. 
Assam forms of the tea plant were regarded as “ degraded ” and conse¬ 
quently the Chinese small-leaved plant was introduced at considerable 
cost with the result that “ for the past 30 or 40 years tho 
planters have deplored the day when the so-called Chinese tea plant was 
brought to India. At present no planter would for a moment dream of 
planting China tea, few would even grow the hybrid, while the majority 
would cultivate but one only of the several so-called indigenous 
stocks.” 1 
2. It is well to remember that several 
serious drawbacks usually attend the cultivation of exotics. In the first 
place the reports circulated regarding the dimensions attained and pro¬ 
ducts yielded by plants are frequently untrustworthy and it is as a rule 
impossible to personally verify these satisfactorily by local inquiries. 
From 1862—1889 statements were frequently circulated that the gum 
trees [Eucalyptus) of Australia attained a height of 400—500 feet and 
even more. Careful measurements made in Australia about 1888, 
however, showed that not a single tree could be found which exceeded 
326 feet 1 inch. It is clear that estimates of timber yield, based on data 
of this kind, and on which calculations regarding the probable profit to 
be obtained from the introduction of these trees necessarily depend, 
would have been worthless. It must also be remembered that estimates 
of value are merely comparative. Prosopis spicigera is undoubtedly a 
very valuable species in desert tracts where practically no other tree will 
grow, but it would obviously be absurd to introduce it into forests 
where many species already exist which are superior in all respects. Simi¬ 
larly statements regarding the value of exotics must be carefully 
considered with reference to the value of those indigenous species which 
it is proposed to replace. 
3. We have also to reckon with the 
widely known and most important fact that, although many plants 
thrive and can be cultivated in various countries and climates, it by no 
means follows that the growth and quality of the commercial products, 
for the sake of which they are cultivated, will remain the same and will 
not deteriorate under such different conditions. Darwin mentions the 
following examples of such deterioration : “ The Hemlock is said not to 
yield conicine in Scotland. The root of the Aconitum napellus becomes 
innocuous in frigid climates * * As the Pistacia lentiscus grows abun- 
1 Commercial Products of India, 1908, pp. i'13, 216. 
E 126 ] 
