Trees of New York State 39 



Variation in the flower — Concluded 



C. TTnion of parts — Continued 



4. Diadelphons stamens. With the stamens united 



by their filaments in two sets. 



5. Syngenesious stamens. With the stamens united 



by their anthers into one strneture, the fila- 

 ments free. 



D. Form of corolla. 



1. Rotate. Wheel-shaped with the limb spreading 



at right angles. 



2. Salverform. Tubular with the limb spreading 



at right angles. 



3. Canipanulate. Bell-shaped. 



4. Urceolate. Cj-lindrical or ovoid and contracted 



in the throat like a vase, 



5. Funnel-form. Tubular, with gradually spread- 



ing border. 



6. Papilionaceous. Similar to the corolla of the 



Sweet Pea, consisting of a standard, two lateral 

 wings and a keel (two petals). 



FRUIT 



General 



The seed-bearing product of a seed plant is known as the fruit. 

 In the Gymnosperms it is usually represented by a cone-like struc- 

 ture consisting of scales bearing seeds in their axils. (Fig. 54.) 

 The fruit of Angiosperms is the ripened ovary with such struc- 

 tures as adhere closely to it. The classification of angiosperm 

 fruits hinges on the proper interpretation of the structure of the 

 pistil. 



Criteria foi' the Interpretation of the Pistil 



The upper (inner) cycle of modified leaves (carpels) which 

 enter into the structure of a flower are designated by the col- 

 lective term of gynoecium. A gynoecium may consist of but a 

 single carpel or an aggregate of carpels. In the latter case +he 

 carpels may retain their individuality as separate simple pistils 

 or they may cohere into a single structure, a compound ustil. 

 A simple pistil consists of but a single carpel ; a compound pistil 

 is made up of two or more carpels. The following criteria may 

 be used to separate simple and compound pistils: 



