7() Floristik und Systematik der Phanerogamen. 



argillotropha, M. Colimensis, M. Micheliana, M. polyanthoides, M. rhodo- 

 dactyla, M. stipitata, Polygonum striatulum , P. leptocarpum, P. cauria- 

 num, Hechtia Techuacana, Cerastinm Barberi, Parnassia Townsendii, 

 Hyptis Seenanni stenophylla, Pentstemon isophyllus, Piptothrix Jali- 

 scensis, Brickellia monocephala, B. pulclierrima, Verbesina gracilipes, 

 V. hypsela, Bidens tereticaulis indivisa and Liabum Tonduzii, 



Trelease. 



Smith, W. G. and W. M. Rankin, Geographical Distri- 

 bution of Vegetation in Yorkshire. Part II. Harro- 

 gate and Skipton D ist riet. (The Geographical Journal. 

 Vol. XXII. 1903. p. 149—178. figs. 1—7 and map.) 



The area surveyed in the present paper has a somewhat complex 

 geology and affords an excellent opportunity for contrasting the limestone 

 Vegetation with that of neighbouring sedimentary rocks, the prime factor 

 in determining the Vegetation of the limestone being the rapid drainage. 

 The chief mass of farmland and woodland oecupies the eastern lowlands 

 and the dales; the moorland is almost all confined to the western high- 

 land. The Vegetation of the sandstones and shales is first considered ; 

 the moors of this district are broad and extensive and can be again 

 classified as cotton-grass moor, heather moor, and grass heath (cf. Part I). 

 The first of these isdominated by Eriophorum vaginatum and E. angusti- 

 folium, whilst Empetrum and Vaccinium Myrtillus vary in amount from 

 place to place. The rainfall is abundant on these moors and in the wet 

 season, the moor is a soaking mass. With regard to the Vegetation of 

 the summits they were in some cases (cf. part I) also oecupied by 

 Vaccinium, but on the summit of Great Whernside this Vaccinium 

 association is quite wanting and the scanty soil Supports a thin Vege- 

 tation of grasses with occasional Islands of peat Transitional between 

 the cotton-grass and the heather moors we find that near the margin of 

 the former Calluna and Erica Tetralix increase in quantity; this is due 

 to drier conditions and in correspondence with this we find, that the 

 area, oecupied by the heather moor, has a lower rainfall and better 

 drainage. The Vegetation of these heather moors is uniform over consi- 

 derable areas and is dominated by Calluna with a number of sub-domi- 

 nant species ( Vaccinium Myrtillus, V. Vitis-idaeus, Erica Tetralix, Pteris 

 aquilina, etc.), which may localiy become dominant and disturb the 

 uniform tone of the heather moor. The taller rushes (Juncus) form close 

 associations (Junceta) exclusive oi other plants and are a prominent 

 feature of the heather moor, oecurring chiefly in the marshy hollows or 

 flats; round their margins numerous associates however oecur. As in 

 Part I it is found necessary to distinguish between dry and wet grass 

 heaths, the former with Deschampsia flexuosa, Festuca ovina and Nardus 

 strieta, the latter with Molinia varia dominant; the grass-heath generali)- 

 forms a fringe round the moorland. 



The woodlands of the sandstones and shales have the oak as the 

 most common deeiduous tree and of the Conifers the Scots pine is most 

 abundant. Four types of woods are distinguished here : gill woods, 

 upland oak woods, lowland oak woods and pine woods. The gill 

 (= „clough" of Part I) woods are those found on the steep descent from 

 the moor plateau and the dominant plants form a loose scrub, consisting 

 of birch, mountain ash, holly, etc., whilst the undergrowth is in part 

 constituted by intruding plants from the moor; there is evidence to show 

 that the distribution of these gill woods was formerly much greater. — 

 The upland oak woods oeeur in the sandstone Valleys (being absent on 

 the limestone Valleys), reaching down to about 500 feet and with an 

 upper limit of 800—900 feet. They often contain a considerable admix- 

 ture of Scots pine and other Conifers. Below 500 feet we find the low- 

 land oak wood, in which Acer Pseudo-platanus and Ulmus montana often 

 have the dominance of the oak; it is distinguished from the upland 

 woods by being damp, shaly and richer in humus and is consequently 



