170 



THE YOUNG NATURALIST. 



opportunity of studying a perennial 

 woody stem, such as we have in the 

 exogens of our ordinary forest trees. 

 The most obvious distinction to the 

 young botanist is in the venation of 

 the leaves, which is known as parallel, 

 because they run from the base to the 

 apex without branching or interlacing, 

 to form a network, and the parts of 

 the flower being in multiplies of three. 

 Evolutionists maintain that this type 

 of vegetable life existed prior to the 

 more highly specialised and developed, 

 and now more abundant dicotyledonous 

 vegetation which abounds on our 

 globe. Be that as it may, there is 

 ample proof that plants similar to our 

 iris flourished at a very early period on 

 our earth's crust, and their general 

 distribution, both in time and space, 

 show that they have been plentiful and 

 widely dispersed. 



The Natural Order Iridacece, which 

 includes such showy and well-known 

 garden flowers as the crocus and gladi- 

 olus, takes its name from the genus 

 Iris, of which there are about fifty 

 species, comprising some of the most 

 gorgeous and brilliant of florist's flow- 

 ers. They are found in all temperate 

 regions of the globe, although only 

 ttfo species are indigenous to Britain; 

 one of these, /. fcetidissima, gladden, 

 Or roast-beef plant, is entirely confined 

 to the southern half of the island, find- 

 ing its extreme northern limit in Dur- 

 ham, where it becomes exceedingly 



rare, although it is abundant in the 

 southern counties, such as Devon. It 

 is easily known from the purple colour 

 of its flowers and the strong, rank 

 odour exhaled from its bruised foliage. 

 The other species, I. pseud-acorus, is 

 very generally distributed throughout 

 the length and breadth of Britain, 

 occurring less or more in every county, 

 but largely influenced by topographical 

 conditions, being always frequent in 

 low-lying marshy localities and rarer 

 in drier, hilly districts. Considered 

 more in detail, we find that in all this 

 order the plants are furnished with a 

 less or more evident stem, which is 

 either wholly underground as in the 

 well-known annually -produced corms 

 of the crocus, or only partially subter- 

 ranean as in the present plant, where 

 the rhizome is cylindrical, prostrate, 

 creeping extensively, with a firm, woody 

 consistency, and of a pale pink or flesh 

 colour when cut, with a rather acrid, 

 astringent taste. Branches are readily 

 given off, and these interlace to form 

 dense matted clumps. The white 

 fibrous roots are readily produced at 

 all points, although chiefly on the 

 underside, where they penetrate the 

 soil and absorb nutriment. The 

 younger portions of the rhizome are 

 covered with a network of thread-like 

 fibres : these are the skeletons of the 

 vascular bundles of the leaves after the 

 spongy parenchymatous tissue has de- 

 cayed. In all monocotyledonous plants 



