88 
LABORATORY EXERCISES 
‘‘ parachute ’’ developing? Explain the use to the plant of the 
changes you have observed in the flower head and in the flower 
stem. 
V. After you have observed definitely what occurs, write an 
account of the development of the dandelion flower and fruit. 
Ill 
THE DEVELOPMENT OF THE FLOWER AND 
FRUIT OF THE MAPLE OR ELM 
I. Observe the date of flowering. (These trees blossom very 
early in spring.) How are the. flowers borne? Are they showy 
or otherwise? Are the stamens and pistil in the same blossom? 
On the same tree? How are they pollinated? What evidence do 
you have of this? What becomes of the scales of the flower buds? 
II. Flowers. If there are staminate flowers — flowers in which 
no pistils are present — what becomes of them? When does this 
occur? What is the function of these? Observe the pistillate 
flowers — flowers in which no stamens are present — of the same 
kind of tree. Are they borne on the same individual as the 
staminate flowers, or on a separate one? If the tree has perfect 
flowers — flowers in which both stamens and pistils are present — 
do these have parts other than the stamens and pistils? Observe 
either the pistillate or perfect flowers throughout their develop¬ 
ment. Note daily the changes which^ occur and the development 
of new structures. Do all of the flowers complete their develop¬ 
ment? In the case of the trees which bear separate pistillate and 
staminate flowers, do both of these develop with equal rapidity? 
Explain. Draw the flowers observed. 
III. Fruits. How long does it take the fruit to develop? How 
are the fruits scattered? Where is the seed held? How far are the 
fruits carried from the parent plant by the wind? Estimate the 
number of seeds on a large tree. Why is it necessary for seeds to 
be scattered? Observe, if possible, when these seeds germinate. 
Draw the fruit. 
