46 NEW ZEALAND NATURE-STUDY BOOK 
stringy, fibrous, and probably hollow. The plant-food 
stored in the root has in fact been used up in nourishing 
the flower and seed. Such plants which flower in the 
second season of growth and then die, are called biennials. 
The production of flower and seed is a great strain on the 
plant, and it is to enable it to bear this effort that so much 
food is stored up. 
During the process of ripening, there is a steady drain of 
nourishing material from the other parts of plant into the 
seed. For example, from the leaves and stem of a Wheat 
plant most of the nutritious material is carried away in 
solution, and deposited in the seed. A seed therefore is a 
reservoir of nourishment, and man cultivates cereal or 
grain crops in order that he may utilise this valuable store 
of food. It is unnecessary to mention these in detail : 
Wheat, Oats, Barley, Maize, etc., are well known, and will, 
if necessary, furnish excellent material for further lessons, 
In the ease of biennials, the plants rest between the two 
seasons of growth. A Carrot (i.e. root of a carrot) for 
example, may be left in the ground during the winter, 
without injuring its power of producing seed the follow- 
‘Ing spring. The cultivator grows root crops in order that 
he may interfere with this resting stage and utilise the food 
stored up by the plant. 
Storage in Leaves. The roots are not the only places 
where plants form reservoirs of food. Inthe Cabbage for in- 
stance, the leaves act as the place of storage. If a head of 
cabbage be examined, it will be found to consist of a number 
of leaves growing on a thick stalk folded tightly together. 
The ones towards the top of the stalk are small, and occupy 
the inner portion of the head, whilst the leaves growing 
from the base of the head are large, and act as a cover envelop- 
ing and protecting those within. These, it will be noticed, 
removed from the light, are much whiter than the outer 
