COLOMBO. 
Added as a Supplement Monthly to the " TROPICAL AQRIGULTURIST. 
The following pages include the Contents of the Agricultural Magazine for 
March :— 
Vol. XIV.] MARCH, 1903. [No, 9, 
INTEKESTING PHENOMENA IN PLANT 
NUTEITION. 
E are told in text-books on Botany 
that ill miiiiy cases the root hairs, 
the ordinary absorptive organs of 
the plant, are replaced by a fungus 
whose hyphae absorb nutriment in 
the same way. Such a fungus 
is termed a mycorhiza which in some cases as 
in the cone-bearers is ectotropic, i.e., the hyphae 
do not enter the cells of the root but run 
between the epidermal cells, while in others as in 
orchids it is endotropic, i.e., the hyphae enter the 
ceils of the root. There is further the phenomenon, 
seen in some trees, where the roots are parasitic 
upon other roots living in the same soil, and are 
modified in structure to suit this modification of 
their absorptive functions, 
Both tiiese jihenomena are very interesting as 
suggesting the means by which such trees as 
are dependent to some degree on other organisms 
for the supply of their food, may have their 
environments made suitable to their I'equirements. 
Under tlie conditions in which they grow, 
it can be imagined that tiie want of the mycorhiza 
in the one case or the absence of the companion 
tree in the other, would result in growth 
under great disadvantages. The question is 
to what extent does Symbiosis exist among plants 
under cultivation, and to what extent could we 
control the conditions under which the plants 
flourish ? 
In an article on the Sandal-wood tree by Sir 
Deidrich Brandis, we are told that this tree is so 
to speak a root-parasite, i.e., it has been ascer- 
tained by microscopic examination that its roots 
attach themselves to the roots of other plants. 
Sir Deidrich mentions the trees for which the 
Sandal-wood has a special affinity, and concludes 
that in order to thrive it is necessary that the tree 
requires its roots to be in intimate contact with the 
roots of other plants of diflerent orders and struc- 
ture and organisation. Indian Foresters would 
appear to have long known, as the result of ex- 
perience, that Sandal-wood thrives p.'.rticularly 
well in company with Casuarina and Lantium. 
Sir Deidrich is reasonably convinced that this tree 
takes up a large proportion of its mineral food 
through haustoria, or sucking organs, from the 
roots of the plants upon which it depends. 
The following questions would therefore seem 
to be very pertinent in regard to any cultivated 
plant. — Is the tree furnished with root hairs for 
taking up nutriment directly from the soil ? To 
what extent are the typical root hairs replaced by 
haustoria or sucking organs ? If at all dependent 
on other trees, what are the best companions for 
the tree in question ? 
It is an axiom in agriculture to give each plant 
plenty of room, but this latest theory would 
appear to show that it is not at all unlikely that 
there is something to be gained by association of 
plants with one another, provided the right plants 
are grown together. Indeed, the striking luxuri- 
ance of virgin forest vegetation appears to suggest 
some such explanation, and even hint at a system 
of natural selection of companions by trees 
that have never been brought under the coutrnl 
of man. Planters will tell us that some forest 
tree?, irrespective of the lightness or density 
of the shade which they afford, ( ind "poSsibly also 
independent of the density or lightness of the 
wood — as to some extent indiojitlng th«3 demand 
