ISO PLANT LIFE. 



exactly. The leaves of the Docks (yRumex), and 

 most of the order to which it belongs, have a mid- 

 rib, which is fairly prominent, even in the young 

 condition. The green part on each side of the mid-rib 

 forms a neat roll, which fits against it. A gummy or 

 slimy matter often covers the young leaf, and the whole 

 leaf, as well as the stem bud, is contained in a delicate 

 white sheath belonging to an older leaf 



The common Bishop-weed (y^gopodiiun podagrarid) 

 sends up its leaves above ground in a very curiously 

 folded condition. The leaf is bent over, so that the stalk 

 and nerves are uppermost ; the delicate green tissue is 

 completely enclosed, and is entirely out of harm's 

 way. Another very nice example of this mode of 

 protecting the bud is the Dog's Mercury (^MeTcurialis 

 perennis). The stem bends over as the leaf of bishop- 

 weed does, and the leaves have similar prominent 

 nerves. In this case the green parts of the leaf are 

 rolled in, and not outwards as in the dock. The curve 

 or arch, formed by the bending over of the stem or 

 leaf-stalk, is of importance, for the young leaf may 

 have to grow up through grass or other obstacles, and 

 this curved or dome-shaped summit can easily push its 

 way through other leaves. As soon as the leaflets of the 

 Bishop-weed, or the stem of the Mercury, have passed 

 through the other leaves, they spread out in their 

 natural position, and take the light for themselves. 

 The Wood-sorrel is another excellent example of the 

 way in which buds are guarded. The buds of those 

 plants which have opposite leaves, usually show the 

 successive pairs enclosed one within the other, in such 

 a way that the mid-ribs of the younger pair fit into the 

 space between the edges of the next older pair below. 

 In the Wound wort {Stachys silvatica) or in the Nettle, 



