56 NOTES ON THE FLORA OF LINCOLNSHIRE. 



differing in humidity or dryness, porosity or impermeability, sub- 

 soil, &c. With the object of finding out the ''why" of our flora in 

 view, and with the Drift maps in hand, I have wandered over the 

 whole county making notes of everything common or rare without 

 distinction ; but more especially of the changes in the flora as the 

 varying outcrops of the underlying strata appeared through the 

 surface drift, or approached the surface as a subsoil, so as to affect 

 the flora. A carefully selected series of soil samples have been 

 taken, with full notes, in case it should be thought advisable to 

 test our plant distribution by chemistry in the future. 



It is absolutely impossible in the limits of a short paper to jot 

 down a tithe of the facts observed. They are practically valueless 

 too from being drawn from so limited an area — 2,787.140 square 

 miles. But many most interesting facts appear after this geological 

 review. As a sample of these we may note that Trifolium ochro- 

 leucon has only been found on the boulder clay. Potentilla argentea, 

 which ranges widely in other counties, is confined to one limited 

 spot on the Spilsby sandstone. Hemiaria glabra is the same on 

 one confined spot on the Lincolnshire limestone. I use these 

 geological names in the limited sense in which they are used on 

 the Drift maps. Cnicns arvensis cannot grow on peat ; but on a 

 thin bed of peat overlying Oxford clay it finds its most congenial 

 home, and where the two are mixed in ploughing it becomes the 

 dread of the farmer. Urtica dioica shows a like repugnance to peat, 

 and if forced by circumstances to struggle on in such unpropitious 

 surroundings slowly changes into the variety microphglla forma 

 suhinermis — at least, so Mr. A. Bennett kindly named my specimens. 

 Festuca in-atensis will only naturally flourish on soils rich in nitrogen, 

 natural or artificial ; but it does not die away when sown as 

 Alopecurus prntensis and DactijUs do, but, just existing, waits for the 

 gradually accumulating fertility of the soil to start it into vigorous 

 life. Poa annua is the nursing grass of rich soils, and Lollum 

 perenne of the poorer. The latter species seizes on the ground after 

 the passing annuals, and Cardmis, Cnicns, and Rume.v have had 

 their short but fertility-bringing day. It retains its hold against 

 all opposition till nitrogen has accumulated and better species of 

 grass force it out ; even then clinging to every spot it can, where 

 they cannot grow, as footpaths, gateways, slopes down to ponds, 

 roadsides, &c. The following seems to be the recognisable order 

 in which the species follow P. annua or L. perenne ; but the quality 

 of the soil and moisture, and question whether there are the species 

 seeding in the neighbourhood has much to do with it : — Poa pratensis, 

 Cynosurus, Poa triviaUs, Ph. pratense, Arrhenathenim, Dactylis, and 

 finally Alopecurus pratensis and Festuca pratensis. Arrlienatlierum 

 and Dactylis are both shade grasses, and so only come when wood 

 or hedge shade is found near ; the former always in limited 

 quantities. F. elatior is never found naturally in our pastures 

 and meadows. The best pasture species are seldom allowed to 

 seed by stock, and how they multiply as rapidly as they do I have 

 not yet discovered for certain. 



When we have a Geo-topographical Botany, fully up to our 



