BOTANY must in the great majority of cases have been the means of introducing it to numerous isolated pieces of water. Spores of ferns are also carried by water, for I have seen seedling species of the bracken (Pteris aquilirm) which have been brought down from Harleston, growing on the flood-mark on the brick walls of wharves in the southern part of Northampton. The sweet flag [Acorus Calamus) has spread by the agency of streams along the larger rivers of eastern and southern England, but in this instance it is to portions of the creeping rhizome being carried down by the stream to some other anchorage, that its dispersal over a wide area is probably due. It occurs by the Ouse at Stony Stratford on both sides of the stream, and has the appearance of being native. The yellow monkey flower {Mimulus Langsdorffii) so fre- quent in some of the Buckinghamshire streams, does not yet appear to be established with us. THE BOTANICAL DISTRICTS Following the example which has been set by the large proportion of modern local floras, I have based the divisions of the county for botanical purposes upon the river drainage, and by doing so have brought the flora of Northamptonshire into harmony with that of the neigh- bouring counties in which a similar plan has been adopted. Those botanists who are interested in plant distribution through the smaller river districts of England, may thus have less trouble in tracing the constituents of each river-flora than would be the case if an artificial or geological basis of division had been followed. Unlike some counties, such as Berkshire, which happen to be wholly in the drainage basin of one large river, Northamptonshire has a more composite system. Owing to the great length of the county, which from Crowland to Aynhoe is seventy miles, and from its ranges of hills, it has been the boast of the county that we send streams to all the neighbouring counties but receive none in return, and we have the water-parting of three different and important river systems all starting within our area, the outlets of which into the sea are very widely separated. They are the Severn, the Thames, and the Ouse. The first is represented by two streams, the Learn and the Avon, which are separate and distinct in our county, but unite in Warwickshire, while the united stream, still bearing the classic name of Avon, itself unites near Tewkesbury with the Severn, whose outfall is into the Bristol Channel. The second consists of the Cherwell, and is an important feeder of the Thames, which falls into the North Sea near the English Channel. The third, the Ouse, which in our area is drained by the Ouse, the Nene and the Welland, each distinct streams, and flowing into the Wash in the German Ocean by different outlets. As the portion of our county drained by the Ouse is large I have thought it well to separate it into five subdivisions. The r.ames and limitations therefore of the seven botanical districts are as follows : — 1. The Avon or Leam This district occupies a narrow strip on the north-western side of the county, and is bordered by the counties of Leicester and Warwick, and corresponds with District 2 of the Flora of Leicestershire, znd with Districts 4 and 5 of Bagnall's F/ora of JFarwickshire, where the drainage of these two streams forms two districts. It may be well hereafter when the know- ledge of the flora of this part is more complete than it is at present to follow Mr. Bagnall's plan of keeping the two river drainages separate. The boundary of the Avon district, from the district of the Cherwell, Nene, and Welland is as follows ; but it must be borne in mind that in some cases, from various causes, the boundary is not precise. From the Warwickshire border near Marston Hill, the turnpike road from Priors Marston to Charwelton is followed. Then the boundary line is carried northwards to Arbury Hill (734 feet), capped with North- ampton sands, which forms the culminating point of the county, and which is therefore in two different drainage systems. From Arbury the high ground to Staverton marks the limit, and from Staverton the turnpike road, the highest point of which is 590 feet, to Daventry forms the boundary as far as to Drayton Lodge, then the line is traced across country by Drayton Grange to Ashby Grange, leaving Drayton reservoir (in the Nene district) on the east, and Bragbrough House on the west. At this point the turnpike road to Barby marks the boundary 57
