LECT. VI.J THE STEM. FIGURE. 277 



ticulated stem is more or less bent at each joint ; 



as in Floating Fox-tail Grass, Alopecurus geni- 



culatus; Three-flower Fescue Grass, Festuca 



triflora, &c. 



Such are the diversities which stems externally 

 present to the eye. But these, although in their 

 natural state they are sufficiently fixed to enable 

 systematic Botanists to employ them as distinc- 

 tive characteristics of species, which could not 

 otherwise be distinguished * ; yet, are apt to vary, 

 owing to peculiar circumstances connected with 

 situation, climate, and soil. Thus we find a stem 

 which, in its natural state, is round, assume a 

 flattened appearance as if two or more stems or 

 branches were united longitudinally side by side : 

 an anomaly which is not uncommon in the Ash, 

 several species of Daphne, the greater Nasturtium, 

 Tropaeolum majus, and many other herbaceous 

 plants ; and is denominated by authors f the clus- 

 tered stem, caulisfasciculatus. It is not easy to 

 account for this effect, since it is evidently not the 

 simple lateral union of one or more stems or 

 branches, a circumstance which might be pro- 

 duced by pressure abrading the epidermis and cel- 

 lular layer of the bark, and bringing the liber or 



* " Caulis in multis plantis ita essentiales praebet differentias, 

 " ut eo demto, nulla certitude speciei." Phil. Bot. 276. 



f Smith's Introduction, p. 127. Keith's System of physiolo- 

 gical Botany, vol. ii. p. 277. 



r3 



