106 VEGETABLE ORGANOGRAPHY. 



from tlie attacks of insects ; but even this use is not pre- 

 sented in a sufficiently evident manner. 



When the leaves or their lobes only bear a hair-like 

 appendage, this receives the name of Bristle (seta; 

 sole) when it is truly a hair, as in Papaver setigeriim, 

 or Chenopodium setigerum, which receive their name 

 from it. When the appendage is short, or a little thick, 

 or has somewhat the appearance of a sting or spine, the 

 name of Mucro (mucrone) is applied to it: we see 

 this particularly in all the Menispermeae, and a multi- 

 tude of other plants. 



Section VII. 



Of Radical Hairs. 



All the kinds of hairs of which we have spoken 

 grow upon the stems, leaves, and in general upon all 

 the organs of plants which are above the neck, and 

 which form part of the ascending vegetation ; but the 

 roots also have a kind of hairs ; these are very small, 

 extraordinarily fugacious filaments, wliich are produced 

 especially during the first infancy of the plant, upon 

 those roots which are exposed to the air. Carradori, 

 who has well observed these organs, has remarked that 

 they never arise from roots sunk in water, nor on the 

 parts of them which this liquid surromids; that they 

 are developed especially upon roots exposed to a moist 

 air, and that darkness is very favourable to their growth. 

 These filaments resemble true Hairs in their form and 

 anatomical structure, but their use may be ver}' different, 

 and resemble that of the Spongioles. Carradori con- 

 siders them as organs destined to absorb the moisture of 



