The Scottish Naturalist. 197 



number of species, medicinal properties, and affinities ; and, in 

 the case of local Floras, there are usually added habitat and time 

 of flowering. But are there not other peculiarities — such as the 

 life-history of plants, the diseases to which they are liable, and 

 the economical uses to which they are put? and are not these 

 equally worthy of notice ? 



Take first Life-history. This surely is a point of very great 

 interest and of considerable importance ; and yet, where do we 

 find it referred to in our taxological books? The omission is 

 certainly unfortunate — indeed, altogether inexcusable, more 

 especially when we consider its value, alike from a scientific 

 standpoint and to the commencing student. For, e.g., plants pass 

 through various phases of development before they reach their 

 mature state, and, in many of them, a plant at an early stage of 

 its growth is so unlike the same plant later on that it may easily 

 enough be mistaken by the beginner as belonging to a different 

 group altogether. A good example is the Common Ash (Fraxi- 

 mis excelsior) which in its growth develops three different kinds 

 of leaves. First come the two cotyledonary leaves, which are 

 coriaceous and strap-shaped, quite unlike in form, in surface, and 

 in consistence to the others. Then come the simple ovate serrate 

 leaves ; and last of all, pinnate leaves, with the leaflets ovate and 

 serrate. Similarly with the Acer Pseudo-platanus, or so-called 

 Plane tree. The first leaves are the two epigeal cotyledons, 

 smooth, strap-like, and uncut. Crenate leaves, wrinkled and 

 ovate or cordate, follow. Then come crenate-serrate leaves, with 

 five well-marked pointed lobes. So with many of the lower 

 plant organisms. There is the remarkable phenomenon of heteroe- 

 cism, and this species of parasitism cannot be adequately repre- 

 sented without distinct reference to life-history. Striking examples 

 have been lately mentioned by the editor himself in the second 

 and third numbers of the new series of this journal. 



But notice should also be taken of the diseases of plants. Not 

 only is this necessary for the sake of completeness, it is further 

 demanded by higher considerations. As is well known, disease 

 in the vegetable kingdom means loss in the animal kingdom ; and 

 intellectual and pecuniary interests are both involved in proper 

 information being communicated on this head. Now, it is an 

 ascertained fact that there are various groups of plants that are 

 liable to distinct diseases (fungal or other), and, in so far as this 

 is an ascertained fact, it admits of being definitely stated. Thus, 

 among the Speedwells, Germander Speedwell ( Veronica Chamce- 



