628 CONSERVATIVE ORGANS. [LECT. XI. 



gans which are occasionally, but not invariably, 

 found connected with the universal vegetable 

 organs. They are never all present on the same 

 species of plant ; but which of them soever is 

 found on any individual is general to the species, 

 and invariably present. All of them are import- 

 ant to the plants on which they are found ; and 

 a knowledge of them, besides throwing great 

 light on vegetable physiology, is of utility to the 

 practical Botanist, in affording characters for 

 specific distinctions. The caullnar and foliar ap- 

 pendages, or those connected with the stem, 

 branches, and leaves, to which we have now to 

 direct our attention, may be classed under the 

 six following heads : Glands, Pubescence, Spines, 

 Prickles, Props, Foliaceous appendages, and ano- 

 malies *. 



1. GLANDS, Glandulce. Linnaeus has defined the 

 vegetable gland to be " a little tumour excreting 

 " an humour -f^;" but this definition comprehends 

 those glands only which are external and elevated 

 above the cutis ; and, as we find many minute or- 

 gans of a structure distinct from the common tex- 

 ture of the part on which they are situated, and se- 



* I have adopted this term from Mr. Keith, because I can 

 suggest no better for the classification of the objects intended 

 to be described under it. 



f " Glandula est papilla humorem excernens." Phil. Bol, 



*.*, 



