IV. VEGETATION OF BRITAIN. 431 



ties. The mingling of Filices, Equisetum, Lycopodium, 

 and Marsileacece with the monocotyleclonous orders, was 

 simply a matter of convenience ; there being no space to 

 make them into a fourth parallel column. In mass of 

 vegetation, possibly, the Ferns exceed the Sedges. 



In the first column, and its continuations in the second 

 and third, devoted to the herbaceous dicotyledons, the 

 orders seem to take sequence very well in accordance 

 with their vegetal prevalence. Plantaginace<B may be 

 considered too low ; but they stand above any other 

 group of only six species. Looking to Buxus, the Eu- 

 phorbiacecB might have claimed place in the second 

 column ; but the rarity and doubtful nativity of that one 

 shrub seemed to forbid the change. SolanacecB and Che- 

 nopodiacece each include one soft herb-like shrub, not 

 warranting their removal to the ligneous group of orders. 



In those orders which are represented in Britain by a 

 single genus to each, the generic name is used instead of 

 the ordinal name, as in some of the former lists. This 

 practice assists to keep in recollection the fact, that 

 ordinal comparisons may be very unequal. In com- 

 paring an order consisting of one genus, with an order 

 including several genera, we compare the simple and the 

 composite, the uniform and the varied, a minor group 

 with a major group. The comparison which sets Lyco- 

 podium against LcguminiferoB, or Hypericum against Ra- 

 nunculacece is really a very unequal contrast. But when 

 that single genus represents a large order of various 

 genera, thus reduced to one in Britain, the inequality is 

 itself an important fact in phyto-geography ; for example, 

 the reduction of Cucurhitacea to the single Bryonia, or of 

 Apocynacca: to the single Vinca. 



