32 LICHENS. 



spindle-shaped, linear, pointed at both ends or only at one, 



constricted in the middle, or nearly globular. Most of them are 



straight, but others are curved, or even spirally twisted. Some 



are simple (or undivided), whilst many have one, three, five, 



seven, or more numerous divisions. A very large proportion are 



colourless, but not a few are yellowish, brownish, or nearly black. 



I have thus summarised the leadino- features and distinc- 

 . . . ^ 



tions of the various parts of a Lichen, having purposely confined 



myself to such genera as are represented locally. 



It is an undoubted fact that a pure, keen air, and espe- 

 cially the salt sea breezes, are highly conducive to the growth 

 and fertility of these plants. To see them in their highest 

 perfection and greatest abundance, we should have to seek cUffs 

 and mountains such as we do not possess here. However, if we 

 cannot boast of such a Lichen-Flora as adorns the Welsh 

 mountains, or the Cornish sea-boards, we have still one quite 

 varied and ample enough to provide the student with working 

 matter for many a day. The British Lichens are by the most 

 recent authorities divided into 76 genera, comprising in round 

 numbers some 2,000 species. Some of these genera are very 

 large, and the species composing them not readily to be dis- 

 tinguished without long and minute examination. I am not at 

 present in a position to estimate, satisfactorily to myself, the 

 number of species which our neighbourhood may possess. I 

 have, however, myself collected examples of at least one-third 

 of the 76 genera, within three or four miles of Stroud — which, 

 all things considered, seems a very fair proportion. As time 

 goes on, many new discoveries and additions may confidently be 

 expected, especially if fresh workers should present themselves 

 in this much-neglected field of botanical knowledge. As an 

 encouraging fact, I may mention that, at any rate, one Lichen, 

 new to science, has been added of late years to our local Flora. 



Excepting those Lichens which are of world-wide distri- 

 bution — such as the common yellow Placodium murorufn, 

 which ranges from Britain to Australia, from Patagonia to 

 Labrador — I should characterise our own Lichen-Flora as being 

 pretty strictly of the N. European type. More southern forms, 

 however, approach so close to us as the St. Vincent's Rocks at 

 Clifton, and some of them may probably be found nearer home. 

 Our most numerous and best-developed Lichens are saxatile 

 or stone-loving — -clothing walls in exposed situations, such as 

 Selsley Hill, or Minchinhampton Common, with various tints of 

 yellow and grey. The arboreal, or tree-forms, are not so abun- 

 dant, nor by any means so generally fertile. Beech-trees, of 

 which our woods are mainly composed, are not great favourites 

 with these plants; indeed, they seem often to remain perma- 



