ORGANS OF FRUCTIFICATION. 



65 



Fii?. 66. 



Some plants creep by their tendrils to a very great height, even to 

 the tops of the loftiest trees, and seem to cease ascending, only be- 

 cause they can find nothing higher to climb. One of our most beau- 

 tiful climbing plants is the clematis virginica, or virgin's bower, 

 which has flowers of a brilliant whiteness. Its pericarps, richly 

 fringed, are very conspicuous in autumn, hanging in festoons from 

 the branches of trees, by the sides of brooks and rivers. 



Sth. Pubescence includes the down,,hairs, woolliness, or silkinessof 

 plants. The pubescence of plants varies in different soils, and with 

 different modes of cultivation. The species in some genera of plants 

 are distinguished by the direction of the hairs. The microscope is 

 often necessary in determining with precision, the existence and di- 

 rection of the pubescence. It has been suggested that these appen- 

 dages may be for similar purposes as the fur, hair, and bristles of 

 animals, viz. to defend the plants from cold, and injuries from otlier 

 causes. 



9th. The Bract, or floral leaf, is situated 

 among, or near the flowers, and is different 

 from the leaves of the plant. You may, in 

 Fig. 66, observe the difference between the 

 real leaves (b, 6,) and the bract (a;) the 

 former being cordate and crenate, the latter 

 lanceolate and entire. 



In some plants, as in several species ol 

 sage, the transition from leaves to bracts is 

 so gradual, as to render it difficult to distin- 

 guish between them, and a considerable part 

 of the foliage is composed of the bracts. In 

 the crown -imperial, the stem is terminated 

 by a number of large and conspicuous bracts 

 These appendages are sometimes mistaken 

 for the calyx. Bracts are green or coloured, 

 deckhious or persistent. The orchis tribe 

 have green leaf-bracts. No plants of the 

 class Tetr adynamia 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 roo^, stem, leaf, and ap- 

 pendages ; v,'e shall next examine the class 

 of organs whose chief use appears to be that 

 of brmging forward the fruit 



LECTURE XI. 



CALYX. 



We are now to consider the second division of vegetable organs, 

 viz.: such as serve for the reproduction of the plant, called organs of 

 fructification. Their names were considered when commencing the 

 analysis of flowers ; but we are now to examine them with more 

 minute attention, and to remark upon their different uses in the 

 vegetable economy. 



You are no doubt pleased to have arrived at that part of the plant, 

 which is the ornament of the vegetable kingdom. Flowers are de- 

 Pubescence — Bract — Difference between tlie real leaf ajid the bract— Recapitu!atio<i 

 —Second division of vegetable organs. 

 6* 



