182 ECOLOGY 



C. Describe the occurrence of the flower buds. When and for how long 

 do the flowers open ? Advantage ? Look for insect visitors. What do 

 these collect ? Are roses probably dependent on insect pollination ? 

 Make a diagram of a longitudinal and of a cross section of the flower. 



D. Study fruit of the rose from material in alcohol or formalin. Are 

 fresh rose hips edible ? Are the seeds ? How long do rose hips remain 

 on the branches ? Advantage ? Have you seen birds eating them ? At 

 what season ? What becomes of the seeds when birds eat the pulp of 

 the fruit ? Are most rosebushes browsed by cattle ? Reasons ? 



E. Is this rose adapted to a moist or a dry habitat ? How ? 

 Prunus serotina, wild black cherry. 



A. What is the shape of full-grown trees ? Size of the largest ones in 

 your vicinity ? 



B. Sketch and describe the leaves. 



C. Sketch a flower cluster. Do cherry and plum trees blossom before or 

 after the leaves develop ? Are they all alike in this ? Advantages of 

 blossoming first ? 



1. Make a diagram of a longitudinal and a transverse section of the 

 flower. How many ovules are there ? Do all mature ? 



2. Look for nectar and nectaries. Do the anthers all mature together ? 

 Are there insect visitors ? 



D. Is the fruit edible ? Do birds gather it ? What evidence is there of 

 wide distribution of the seeds ? Why do cherry trees often grow beside 

 fences ? 



The rose family (as found in temperate regions) is divided into four sub- 

 families, — Spiroeoidece, Pomoideos, Rosoideoe, and PrunoidecB. Familiar rep- 

 resentatives of these are the Spiraea, the apple, the rose, and the cherry. 

 The most obvious differences between these subfamilies depend on the 

 development of the receptacle and the way in which the carpels are borne 

 on or within it. In the Spiroeoideoe the receptacle is flattish and the carpels 

 are borne on its surface. In the PomoidecB the flowers are epigynous and 

 the carpels appear to be grown fast to the hollow inner wall of the recep- 

 tacle. In the Rosoideoe the carpels are in some genera (as in the rose) mod- 

 erately attached to the ijiterior of a hollow receptacle, and in other genera 

 (as in the raspberry, the blackberry, and the strawberry) they are borne on 

 the outside of a more or less elongated and thickened receptacle. In the 

 PomoidecB there is often but one carpel, which ripens only a single seed, 

 inclosed in a fleshy stone fruit. 



Is there any general similarity in the size, habit, and degree of woodiness 

 of rosaceous plants ? 



How could all rosaceous plants be roughly classified as regards their 

 leaves ? 



