154 



HARD WICKE' S SCIENCE- G OSSIP. 



Call it dull if you will : to those whose eyes and 

 ears are open, such a life in such surroundings has 

 much of the keenest interest — it is that of our England 

 unadulterated. Let us enjoy it while we may. 



M. E. Pope. 



NOTES ON THE MODIFICATIONS OF 

 ROOTS. 



THE axile roots, such as the conical tap-roots, 

 which occur in Aconiium iiapcllus^ Pcucedamim 

 sativujn, and Daucus carota, are a direct prolongation 

 of the stem ; as also the fusiform i-x'^-xooi oi Raphamts 

 raphanistruin, and the napiform tajD-root ol Brassica 

 rapa. The contorted root of Polygonum listorta, 

 and the premorse root of Scahiosa sicccisa, seem to 

 be only modifications of the rhizome, but are some- 

 times mistaken for true roots. 



The tuberculated roots, as the palmate tubercules 

 of Orchis maculata, are only formed by the enlarging 



Fig. 120.— Abnormal Tubercules of Orchis macidata. 



of several adventitious fibrous roots which have 

 cohered at their bases, and left their extremities free, 

 which forms the divisions of this kind of tubercule ; 

 those adventitious roots which ascend from the junc- 

 tion of the tubercules with the stem have slightly 

 enlarged, but otherwise preserved their primary form ; 

 this may be ascertained by a specimen I found in 

 Sussex in 1890, which had no perfect tubercules, but 

 had in their place several adventitious fibrous roots 

 which should have cohered and formed the two 

 tubercules ; all these fibres were a little swollen at 

 their upper ends. 



The ovoid tubercules of Herminium, Ophrys, and 

 Aceras, etc., are formed by complete cohesion of 

 several fibres, or by the enlarging of a single one. 

 In the fasciculated roots of Jianuncidiis ficaria, this 

 same enlarging of some of the adventitious roots is 

 obvious ; on a single plant may be found all the 

 modifications from a fibrous adventitious root to a 

 fasciculated, or even ovoid tubercule. The dahlia 

 exhibits another form of adventitious fasciculated 



roots, where several of the fibrous roots have cohered 

 and formed an elongate ovoid tubercule, the ends only 

 are left free at the extremities of the tubercules. In 

 CEyianthe pimpindloidcs and Spircca filipendula we 

 have the nodose adventitious roots ; in the former 

 species we have the swelling about the middle of the 

 fibre, while in the latter it is near its extremity ; in 

 (Enanthelachenalii, the fibres are but slightly swollen. 



Fig. 321. — Palmate Tubercules of Orchis maculaia. 



Fig. 122. — Palmate Tubercules of Orchis viaculata. 



which must have been the primary of those of CE. 



pimpinelloides. 



It seems that the stem was the primary form of 



roots, since all roots have more or less the structure 



of stems ; those roots so different from the stem 



modifications, may only have lost their structure with 



time. 



Henry E. Griset. 



