- 4 8- 



of each joint being made to fit into the top of the joint below, 

 while the other is flanged, as we might say, to contain the end of 

 the joint above it. So perfect is this arrangement in some species, 

 that the stems may be pulled apart, joint by joint, and recon- 

 structed again, to all appearances like they were originally. The 

 whole body of the plant — rootstock, stem and branch — is con- 

 structed in this manner. To the casual observer the scouring 

 rushes have no leaves, but if one will look more closely at the stem 

 he will see at the point where two sections meet, a circle of tooth- 

 like papery scales which are really leaves but which are apparently 

 of no use to the plant in that capacity ; in fact the scouring rushes 

 appear in somewhat the same predicament as the cacti where the 

 stem has to perform most of the duties of leaves. 



Our plants may be divided into two sections by the way in 

 which they bear their fruiting parts. In the section to which our 

 earliest species belongs the fronds are annual, and the fertile 

 spikes are often much different from the sterile fronds; in the 

 other the fronds are evergreen and fertile fronds are like the J 

 sterile except that they bear a cone of fruit at the tips. 



The first species to appear in spring is the field horsetail 

 (Bquisetum arvcnse) . It is distinguished from all others by the 

 fact that the fleshy fruiting spike dies soon after the spores are 

 shed and is followed by green sterile fronds consisting of a stem 

 and simple branches. The sheaths on the branches have four 

 teeth. A species much less common is Bquisetum pratense. It 

 resembles the common species very much, but the branches have 

 sheaths with three teeth, and the fertile spikes do not die. After 

 shedding their spores the upper spore-bearing portion dies, while 

 the lower part puts out simple branches like the sterile fronds. 

 When these two species are fruiting, that is in early spring, one 

 may find in moist rich woodlands a third species, the wood horse- 

 tail (B. sylvaticum) , which is quite the handsomest species in the 

 genus, perhaps the handsomest thing that the woodland ever 

 produces. It will be known at once by the fact that the branches 

 are themselves branched and form a series of little green plat- 

 forms with drooping edges around the stem. The fruit-spikes are 

 at the top of fronds, otherwise like the sterile, and when the 

 spores are shed, the parts which bore them die. A muddy ditch 

 or the shallow margin of a lake or stream is the best place to look 



