Trees. 315 



from flowering plants in their being refreshed by the descending 

 water of the rain. They cannot, like trees, raise water as sap 

 •within themselves. 



The first appearance of anything like a tree seems to have 

 been in old red sandstone times, when gigantic clubmosses be- 

 longing to the same class as our little clubmosses appeared. 

 These were, however, very clumsy and uneconomical, considered 

 as trees. Xote especially how wasteful as regards the catching 

 of light. Especially note the monotonous regularity both of 

 foliage and branching. Yet types of this sort of tree are found 

 not merely in clubmosses; many conifers show it, especially 

 monkey-puzzle, Araucaria, Thuja, and some Australian veronicas. 

 The weak point consists in the stem being covered by the leaf 

 bases, and in the small size and simple shape of the leaves. 



A very early type of plant is that called by botanists the 

 ■"rosette," very familiar to us in the daisy and dandelion. 

 This is found in the clubmoss group — Phylloglossum, in ferns, 

 many bulbous plants, and in fact most of the monocotyled')ns. 

 The stem is extremely short, the leaf bases cover the stem, but 

 the leaves themselves are often large. In our common British 

 dandelions and plantains, the circle of leaves is always close to 

 the soil. Yet many of them live several years. In the 

 dandelion the root regularly dies away, and contracts, or shortens 

 so that the tuft or rosette is kept low. Plantagos have special 

 roots which grow at a slant downwards. These roots contract 

 or shorten, and haul down the rosette of leaves, so that they 

 are kept in the most favourable position (close to the ground). 



But, suppose this did not happen, let us imagine the stem 

 to grow regularly every year, what would happen? The palm 

 tvpe of tree would be formed. A column slender and 

 stately with a rosette or crown of leaves at the top. We find 

 many trees of this type. 



Tree fern, the cycad or sagopalm, and the tree palms. 

 There are even dicotyledons of this type, but they are rare, and 

 why ? It is not the best type because the trunk is still covered by 

 the leaf bases, and the area shaded is just the diameter of the 

 one rosette or tuft of leaves. Thus the shade area depends on 

 the size of the leaves, and cannot increase. The area shaded 

 by a voung plant will be very nearly the same as that covered 

 by a veteran. Full advantage is not taken of its long standing. 



