EXPLANATION OF THE PLATES. 



Plate XXIV. Tilia Amerigan'a. 



L A flowering branch, natural size. 



2. Diagram of a flower. 



3. A flower, with two of the sepals and petals removed, enlarged. 



4. A cluster of stamens, with their petaloid scale, enlarged. 

 6, A stamen enlarged. 



6. Vertical section of an ovary, enlarged. 



7. A cross section of an ovary, enlarged. 



8. An ovulej much enlarged. 



Plate XXV. Tilia Americana- 



1. A fruiting branch, natural size- 



2. Vertical section of a fruitj enlarged. 



3. Cross section of a fruit, enlarged. 



4. A seed, enlarged. 



6. An embryo, with the five-lobed cotyledons displayed, much enlarged 



