THE FIELD HORSETAIL 95 



will see that the collars are formed first, and that the branches 

 arise inside, just above the attachment of the leaf-collar to the 

 stem, and push their way out, each bursting from the collar after 

 bulging it out. The horsetail, then, has no green leaves, only 

 scaly ones joined at their bases which protect the buds of the 

 branches. On examining a stem you will find that it is ridged, 

 and that the ridges run from the stem into the teeth of the next 

 leaf -sheath above, also that the ridges of each joint alternate 

 with those of the joints above and below. Each branch has 

 four ridges, though the main stem may have a dozen or more. 

 The stem is hollow, except at the ends of the joints (where the 

 leaf-sheath and branches come off), which have a solid partition 

 to strengthen the stem. A cross-section of the stem shows, 

 besides the large central cavity, a series of outer canals, one 

 corresponding to each groove on the outer surface. The stem is 

 very hard at the outside, owing to the presence of flinty matter 

 in the skin. 



If you mark the position of a patch of field horsetail before 

 the green shoots die down in autumn you will notice, on visiting 

 it in early spring (April), a number of shoots of a very different 

 kind growing up. These are the fertile shoots, which bear the 

 spore-cases. The fertile shoot is softer, thicker, and shorter 

 than an ordinary or barren shoot, and is pale-coloured (having 

 little or no chlorophyll) and usually unbranched. It has, how- 

 ever, the characteristic leaf-collars. The club-like end of the 

 fertile shoot is at first compact, and shows on its surface lines 

 marking it out into hexagonal areas. As the club, or cone, en- 

 larges we see that each hexagonal area is a mushroom - like 

 structure or stalked scale. The scales are arranged in circles on 

 the stem of the cone, and each bears a number of spore-cases 

 attached to the flat part, and lying around and parallel with the 

 stalk. Lay a ripe cone on paper ; after a time you will see 

 numerous brown spores which have escaped by the bursting open 

 of the spore-cases. Each spore has four threads attached to it. 

 If you shake a ripe cone over a sheet of paper or a glass slide 

 you will probably, while examining the spores with a lens, see 

 these threads moving about in a curious way. When you breathe 

 on the spores the threads suddenly become coiled up around the 



