60 Pasture Problems 



(3) Plants which come in by themselves on young leys but which 

 disappear as the field approaches to the semi-natural may further be 

 called Tertiary indigenous species ; these have been discussed provisionally 

 elsewhere (see footnote 1, p. 58) and will be dealt with in detail in a 

 subsequent paper. Plants which are indigenous in a district but which 

 do not naturally contribute to the flora of a well-marked type of grassland 

 have been called locally exotic; and those which are not indigenous 

 in a district exotic (see footnote 1, p. 55). 



(4) The above classifications and distinctions are apphcable to 

 all districts and to all types of grasslands. It must, however, be 

 emphasised that what has been brought forward concerning every 

 individual species is only claimed to apply in toto to the types of grass- 

 land investigated and in the districts under review. A knowledge of 

 other counties, however, suggests that many species would fall into 

 the same categories and behave in a similar manner elsewhere. The 

 following generahsations are, at all events, justified by the data here 

 produced. 



(5) The number of primary species on most types is not consider- 

 able. When a field long under rotation husbandry is put down to 

 grass, the primary species are usually late to come in ; this is particularly 

 true of Bromus erectus (on the Cotswolds), Molinia caerulea, Nardus 

 stricia, Triodia decumhens, and Festuca ovina; and if they come in early, 

 they do not rapidly make their normal contribution to the herbage^. 

 Primary species which sometimes come in early are plants which are 

 frequently met with as arable land weeds, e.g. Poa trivialis, and Festuca 

 rubra (at lower elevations and on the better soils) and Agrostis vulgaris 

 (on the poorer soils). 



(G) The various stages in the process of stabihsation of semi- 

 natural grasslands — through tended to untended and thence into natural 

 types — have been summarised at the end of Section IV (pp. 39-40). 



(7) The relation of primary and secondary species to their commer- 

 cial and sown counterparts is as follows (see also summary to Section V, 

 pp. 51-59). Either 



(a) The commercial seed does not appreciably hasten the appear- 

 ance or add to the contribution of the desired plant. This is true of 

 sowing Festuca ovina, or other fine leaved fescues and is, in many cases, 

 equally true of Anthoxanthutn odoratum; the inclusion of such seeds 

 in mixtures is not justified economically. It is far from certain that 



^ I.e. they may fall below their minimum or exceed their maximum figures. Poa 

 trivialis for instance on good land often exceeds its maximum figure on young leys. 



