52 NEW ZEALAND NATURE-STUDY BOOK 
arising in axils of the older overlapping leaves. The roots 
grow downwards from the base of the stem. 
In the Onion the fibrous roots hang downwards from 
the lower surface of the short plate-like stem. The bulb 
itself consists of a number of thick white fleshy bases 
of leaves overlapping each other, and forming the edible 
part of the plant. 
Bulbs usually flower either early or late in the year, 
at a time not very favourable for the production of food 
by the leaves. In the case of the Onion a flowering 
stalk grows up from the centre, blossoms, and produces 
seed, the food supply for the process being obtained 
from the swollen bases of the leaves. In the case of the 
Lily the new leaves work until. they have stored up . 
sufficient food for the next season’s flower and then die 
down. 
The Rhizome or Root-stock. The Rhizome or 
root-stock is well seen in many of the grasses, in garden 
Mint, in the Iris or Flag-lily, and in New Zealand Flax. 
Fig. 43.— Root-stalk of a Perennial Grass. 
a a', first year’s growth; b b', second year’s growth; ¢ c!, third year’s growth 
' d, terminal underground bud. 
In the diagram the underground stem (a) gradually 
bends out of the ground, becomes erect (4) and bears 
flowers. But the base of this erect portion produces 
«i bud which continues to grow under the surface for a 
\ 
