88 



ORGANS OF FRUCTIFICATION. 



hairs. The microscope is sometimes necessary in determining 

 with precision the existence and direction of the pubescence. 

 It has been suggested that these appendages may be for similar 

 purposes as the furs, hairs, and bristles of animals ; to defend 

 the plants from cold, and injuries from other causes. 

 Fig. 46. 



9th. The Bract is a leaf among or 

 near the flowers, different from the 

 leaves of the plant. You may in this 

 branch (Fig. 46) observe the differ- 

 ence between the real leaves (b, 'b) 

 and the bract (a) ; the former being 

 cordate and crenate, the latter lanceo- 

 late and entire. 



In some plants, as in several species 

 of sage, the transition from leaves to 

 bracts is so gradual, as to render it 

 difficult to distinguish between them, 

 and a considerable part of the foliago 

 is composed of the bracts. In some 

 plants, as the crown imperial, the stem 

 is terminated by a number of large and 

 conspicuous bracts. These appen- 

 dages are sometimes mistaken for the 

 calyx. Bracts are either green or 

 coloured, deciduous or persistent. The 

 Orchis tribe have green leaf-bracts. 

 No plants of the class Tetradynamia 

 have bracts. 



We have, in regular order, considered the first of the two 

 classes of vegetable organs", viz : such as tend to the support 

 and growth of the plant, including root, stem, leaf and append- 

 ages ; we are soon to enter upon the class of organs whose 

 chief use appears to be that of bringing forward the fruit, or 

 the organs of reproduction. 



LECTURE XL 



Calyx. 



We are now to consider the second division of vegetable or- 

 gans, viz. : such as serve for the reproduction of the plant, usu- 

 ally called organs of fructification. Their names were consid- 

 ered, when commencing the analysis of flowers ; but we aro 



Bract Difference between the real leaf and the bract Recapitulation S 

 eond division of vegetable organs. 



