Querceta Sessili-Florae) of the Silurian and Malvernian Strata Near Malvern Author(S): E

The Durmast Oak-Woods (Querceta Sessili-Florae) of the Silurian and Malvernian Strata near Malvern Author(s): E. J. Salisbury and A. G. Tansley Source: Journal of Ecology, Vol. 9, No. 1 (Sep., 1921), pp. 19-38 Published by: British Ecological Society Stable URL: http://www.jstor.org/stable/2255758 Accessed: 26-06-2016 18:50 UTC

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THE DURMAST OAK-WOODS (QUERCETA SESSILI- FLORAE) OF THE SILURIAN AND MALVERNIAN STRATA NEAR MALVERN

BY E. J. SALISBURY AND A. G. TANSLEY.

(With Plate 11.)

Quercetum sessiliflorae (woodland dominated by the Durmast oak) occurs so generally, in this country, on the various soils derived from the older siliceous rocks, that in Types of British Vegetation the association was regarded as typical of these soils, as indeed it is'. It was mentioned however (p. 137) that this type of oak-wood also occurred on later siliceous (secondary) rocks, such, for instance, as the Upper Greensand of Devon, and we have since indepen- dently shown (Tansley, '13, Salisbury, '18, p. 15) that it exists also on tertiary and post-tertiary beds in Hertfordshire and Middlesex. With regard to its occurrence on soil derived from calcareous rocks Quercetum sessiliflorae was mentioned in Types of British Vegetation (p. 139) as existing on Carboniferous Limestone at Killarney in Co. Kerry, and one of us has since shown that it is found on the same strata in North Wales (Salisbury, '16, p. 3) and on calcareous slates in Cornwall (unpublished). It is also recorded from the Carboniferous Limestone of the Wye gorge at Symond's Yat (Armitage, '14, p. 103). In Types of British Vegetation an association of the two British oaks (Q. robur and Q. sessiliflora) was described as characteristic of deep sands (p. 92) where either one or the other species may become dominant. It thus becomes of importance to ascertain the actual factors which deter- mine the dominance of Quercus sessiliflora in the British Isles. Some progress has already been made in this task by one of us (Salisbury, '18) who concluded (pp. 47, 48) that the contrast with woods of Q. robur depends, at least partly, on a higher acidity, corresponding with a lower content of soluble mineral salts and of water. The present paper presents the results of a study, not so thorough as could be wished, of the extensive woods of Q. sessiliflora occupying the Malvernian and Silurian strata of the Malvern district. The latter include limestones of the Wenlock and Ludlow series. The woods investigated, with the rocks on which they occur, a're given below.

1 This correlation does not apparently obtain universally in the woods of southern and west- cehtral Europe. Some of the records are, however, misleading owing to failure to separate the commonly calcicolous Q. pubescens from its close ally, Q. sessiliflora.

2-2

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MALVERNIAN: Woods on Hollybush and Raggedstone Hills. Wood east of Wynd's Point (Uriconian?). SILURIAN: Upper llandovery series (May Hill Sandstone and Tarannon Shales.) High Wood (Cowleigh), Rough Hill Wood (Cowleigh), Park Wood (Wych), News Wood (near Eastnor Park), Gullet Wood (partly on Lingula Beds). Wenlock series. Wenlock Limestone. Great Vineyard Wood, Ten Acre Coppice, Six Acre Coppice, Cother Wood, Bank Wood, Slatch Coppice, Horsenut Coppice (near West Malvern), the Ridgeway (Eastnor Park), Coneygree Wood (Ledbury). Woolhope Limestone. Horsecroft Coppice (West Malvern), part of High Wood (Cowleigh). Ludlow series. Aymestry Limestone. Rowburrow Wood, High Grove (Mathon), Knell Coppice, Brockhill Coppice (Colwall). These woods occur on the southern part of the Malvern chain itself (Mal- vernian) and on the comparatively narrow belt of steeply tilted Silurian rocks that flank the chain on the west'. There can be little doubt that they represent " semi-natural " woods, i.e. more or less modified relics of primitive woodland. According to the Victoria History of Herefordshire (p. 296) clearance of forest had already begun here in Norman times. Part of the area at least belonged to the Great Forest of Malvern Chase, which was partially disforested in 1632 to provide money for Charles I. Much of it passed into cultivation, and the existing woods largely occupy abrupt slopes and ridges. This distribution, together with the large number and variety of shrubs in the undergrowth, and the occurrence of rare or local herbaceous species are clear indications of descent from primitive forest. There has been a certain amount of local planting, but even where this has been extensive (e.g. on the Ridgeway in Eastnor Park) there seems no reason to suppose that the replacement of Q. sessiliflora by Q. robur has in any way modified the ground flora. This is well seen in the planted woods on made-up ground below Wynd's Point, resulting from the road construction carried out some 60 years ago. Though containing a good deal of Q. robur these woods, allowing for their floristic poverty, possess a ground flora practicallv identical with that of the Q. sessiliflora woods on the Hollybush Hill. The clearance also favours the development of light-demanding "nmarginal" species, which persist long after the shade conditions return (cf. Salisbury, '16, p. 97).

1 For an account of the geology of the district the reader is referred to the excellent paper by Richardson ('05) and the earlier monographs of Groom ('99, '00) and Phillips ('48).

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The ridge of the Malvern Hills themselves, composed of Archaean (Mal- vernian) rocks, is almost bare of trees as far south as the Herefordshire Beacofa. Its slopes are now grassland, long used as sheep pasture, but with extensive tracts of Ulex Gallii and Pteridium aquilinum. The following species, which include shade and "marginal" forms, have been noted by us on these slopes.

Euphorbia amygdaloides a. Arum maculatum v.r. Oxalis-acetosella f. Conopodium denudatum f. Potentilla sterilis f. Teucrium scorodonia f.-. Fragaria vesca f. Nepeta glechoma o. Scilla nutans f. *Corydalis claviculata L.a. Luzula pilosa o. *Digitalis purpurea L.a. Stellaria holostea o. *(especially on burned areas) Ficaria verna r.

The presence of so many woodland species suggests that the lower slopes of the northern portion of the Malvern chain were once wooded. South of the Herefordshire Beacon, especially on and around the Hollybush Hill, there are still extensive woods. Most of the woods are regularly coppiced. On the whole the coppice is tall and suggests a long rotation period (which may be connected with the use of the coppice for hop poles), and it is probably as a consequence of this that -light demanding species tend to be confined to the wood margins (cf. Salisbury, '16, pp. 97-98). Only a few light intensity determinations were made, during the "light phase." Thus in Coneygree Wood intensities of from 28-50 per cent. were observed, with 37 per cent. as the average of all readings. In Hollybush Wood the average was 46 per cent. The observed range of light intensity for the Q. sessiliflora woods of Hertfordshire in which a shrub layer was present was, during the light phase, 25-72 per cent. This comparison suggests a simi- larly low illumination in the Malvern woods as compared with Q. robur woods.

Climatic and Physiographtic Features. Unfortunately there are no rainfall data for the actual woods, which mostly occupy higher ground than the rain-gauge stations. The nearest is Mr Bickham's at Underdown, Ledbury (307 feet) which is quite close to Coneygree Wood, and shows an average of 26.67 in. for the twenty years 1880-1900. The higher wooded hills, which reach an altitude of 700-800 feet, would no doubt show a higher figure, but the rainfall on these probably does not greatly exceed 30 inches. The steepness of slope brings about considerable erosion along the lines of drainage. The tracks through the woods on the Silurian Limestones, acting as water-courses, frequently become excavated into " holloways " (Plate II, Fig. 2) thus facilitating run-off and accelerating the leaching of the surface layers of the woodland soil itself. This feature is well seen in Coneygree Wood, Ledbury and in the woods in the parishes of Mathon and Colwall. On the leached surface

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layers of the main wood floor are many species generally associated with non- calcareous soils, while-on the sides of the holloway paths the plants are of a markedly calcicolous type. Towards the bottom of the slopes, where the more basic soil constituents will tend to accumulate, plants such as Mercurialis perennis attain their greatest frequency. The removal of the finer particles towards the base of the slopes will also tend to increase this contrast, since the supply to the roots of soluble mineral salts depends on the aggregate surface presented by the particles. The soils derived from the beds of shale are mostly cultivated. Where present in the wooded areas they are situated in the valleys and bear a some- what basic type of vegetation. Their occurrence is, however, local, and is only a minor factor in determining the nature of the flora at the foot of the hills. These ancient rocks all agree in being very hard, and hence erosive action, which tends to mask leaching, is only locally important.

Edaphic Factors. From the geological standpoint the soils investigated are situated on three very distinct types of rock: (a) the Malvernian (Archaean) crystalline rocks of the Malvern Hills themselves, of varying lithological composition, but relatively rich in bases, (b) the May Hill Sandstone, and (c) the Silurian Limestones of the Wenlock and Ludlow series.

Mechanical Analyses of Soils'.

Strata ...... Wenlock Limestone Aymestry Limestone Locality ...... Cother Wood Rowburrow Wood

Ridge West slope

- -~~-T B5 B6 B1 B2 B3 B4 Depth ...... 0-2 in. 15-18 in. 1-4 in. 0-1 in. 11-4 in. 4-10 in. 3-I mm. (fine gravel) 5-2 6-8 1-4 2-2 2-0 4-1 1-2 (coarse sand) 4-4 9.1 0-8 1-6 0-6 1-8 *2--04 (fine sand) 5-2 71 44 6-9 8-8 10-6 -04-01 (silt) 17-5 14-2 31-8 32-6 38-6 36-7 *01- 002 (fine silt) 23-5 16-0 34 6 21-1 24-9 22-9 Below *002 (clay) 6-8 . 4-9 9 2 7-6 9-8 9-8

The calcareous factor in the vegetation of (c) which is especially conspicuous on the margins and path-sides, is quite obvious from the lists of species (pp. 25- 30). But the relative richness in bases of the soils derived from the Malver- nian rocks, and the marked leaching of the surface layers of soil of the wood floor has tended to assimilate the general vegetation of the Silurian and Malvernian woods. With regard to the factor of soil depth, which Moss regarded as important in determining the dominance of Q. robur or Q. sessiliflora, it may be remarked that several of the limestone exposures show a soil depth adequate to support Q. robur, which does in fact occur but is very seldom dominant. 1 The cost of these analyses was defrayed by Royal Society grants.

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The analyses furnished are not so numerous as could be wished, but the data bring out certain points very clearly. The most striking is the pronounced leaching which has taken place in the surface layers of the soil. For, whilst the CaCO3 content of the Wenlock Limestone varies fr6om 60 to 74 per cent., and that of the soil at 3 feet, between partially disintegrated rocks, from 7 to 23 per cent., the surface soil of the wood floor, especially on the level or on gentle slopes, has a normal lime content, even after removal of litter and raw humus, of less than one per cent.-in other words it is what would be commonly regarded as a non-calcareous soil. The sample B 5, which has a much higher lime content (20*9 per cent.), was taken from a steep escarpment slope (30-35?) of the Wenlock Limestone, covered with mild humus, and occupied by a coppice of Corylus, Fraxinus, Acer campestre and a little Q. robur, with Clematis Vit- alba. The ground vegetation consisted mainly of Arum maculatum and Mer- curialis perennis. In this case we have a typical calcareous woodland soil, and the corresponding plant community is not characteristic of these woods as a whole. The proportion of potash, magnesia and phosphates tends, on the whole, to be higher in the surface than in the deeper layers. This is easily understood when we remember that the rate of leaching of lime is very much higher than that of these substances and that the original rock consists very largely of calcium carbonate: hence the leached residue will contain a relatively high proportion of the other bases. Added to this we have the fact that plants are constantly absorbing as necessary foods the three substances in question, which thus reappear in the surface humus. Not only has leaching resulted in removal of bases but an actual acidity has developed as shown by the high "lime requirement" of the surface soil, especially on the flat floor of Coneygree Wood. The lime content of the Aymestry Limestone (50 per cent.) appears to be lower than that of the Wenlock, and correspondingly the soils show a higher "insoluble residue." Mechanical analyses show a much higher aggregate of the silt and clay fractions. Some beds are indeed very impure limestone, and towards the Upper Ludlow pass into niudstones. The surface soil of the general wood floors have a range of lime content about equal to that of most of the Wenlock, indeed in one case only rising to 1-43 per cent. The leaching effect is as strongly marked here, and again'there tends to be a concentration of potash, magnesium, and phosphates in the surface layers.

Electrical Resistances.

A comparison of the electrical conductivities of the filtered solutions made by shaking up an air-dried sample of 50 grams with 50 c.c. of water from each of the soils (for method see Salisbury, '18, p. 22) gives perhaps a better idea of the soluble mineral salts actually available for plant roots than chemical analysis of the soil, especially since the high proportion of fine particles makes

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it probable that adsorption plays an important role in retaining salts in the soil. The following results were obtained with the same instruments and couple as were used for the Hertfordshire soils (Salisbury, 1,c.):

Resistance Wood Soil in ohms News Wood (Eastnor Park) May Hill Sandstone 2020 Rowburrow Wood (Mathon) Aymestry Limestone 1650 [Balls Wood (Hertford) Clay 1500] High Grove (Mathon) Aymestry Limestone 1500 [Average of Hertfordshire Q. sessiliflora woods - 1245] Wood at Wynd's Point ? Uriconian 954 [Average of Hertfordshire Q. robur-Carpinus woods 780] Coneygree Wood (Ledbury) Wenlock Limestone 520 It will be seen that most of the Malvern soils show a high resistance-i.e. a low content of electrolytes (soluble salts)-comparable with, or higher than the Hertfordshire Q. sessiliflora woods. Of those tested, the Coneygree Wood (Wenlock) soil alone shows a resistance lower than the average for that of the Q. robur-Carpinus woods of Hertfordshire.

Floristic composition.

Classified list of the constituent species of the Quercus sessiliflora woods of the Malvern area. Names of planted trees in italics. Geological formations on which the species occur

Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone I Trees and Shrubs Acer campestre ...... f. f.c.-l.ab. f.c.-ab. o. ,, pseudoplatanus ...0 ...... Alnus glutinosa (by streams) ... l.f. b.c. r. (1) Betula alba ...... f. v.c.-o. o.-l.ab. f.- .a. , pubescens ...... v.r. Carpinus betulus ...... - - r.r. Castanea vulgaris ...... f. f.-l.ab. + Clematis vitalba (margin) ...... r.r.-l.c. r. f.-ab. o. Cornus sanguinea f...... o f. . f.c.-l.ab. o.-f. Corylus avellana ...... f.c.-v.c. ab. v.c.-ab. ab. Crataegus monogyna ...... o.-v.c. o. f.-ab. o.-f. , oxycanthoides ...... ? - + Cytisus scoparius (margin) ...... f.-l.c. o. r. o.-r. Daphne laureola ...... v.r. - r.r.-l.f. o. Euonymus europaeus ...... + r. o.-f. r.-c. Fagus sylvatica ...... r. - l.c.-o. Fraxinus excelsiorl ...... f.-l.ab. lf.-l.c. f.-ab. r.-l.ab. Genista tinctoria (margin) ...... r. (2) Hedera helix ...... o. o. o.-c. f. Hypericum androsaemum ...... - - - + Ilex aquifolium ...... f.-I.ab. o. o.-r. o. Juniperus communis ...... r. Ligustrum vulgare ...... r. - f.c.-o. Lonicera periclymenum ... f.-c. ab.-c. o.-f. c. , xylosteum...... + Populus tremula v. villosa ...... o.-f. f. + 1 Confined to damper tracts except on calcareous soils.

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Geological formations on which the species occur

Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone I Trees and Shrubs (contd.) Prunus avium .o.-l.c. r. f.-v.c. o.-l.f. cerasus ...... r. domestical ...... r. spinosa ...... o.-f. + f. r.-f. Pyrus aucuparia ...... f. o. r. r.-f. malus v. mitis ...... r.r. + + r.r. torminalis ...... ? f.-l.ab. l.a.-r. o.-l.f. Quercus robur ...... o.-f. f.c.-o. v.c.-o. r.r.-o. Q. robur x Q. sessiliflora ... o.-v.r. f. o.-v.c. f. Quercus sessiliflora ...... v.c.-ab. ab. r.-ab. ab. Ribes grossularia ...... l.r. r. ,, rubrum...... + Rosa arvensis...... r.r. o. f.-c. + canina...... o. f. o. lutetiana ...... + ,mollissima ...... + pseudomollis ...... + scabriuscula ...... + tomentosa ...... o.(1 uncinata ...... + Rubus anglosaxonicus ...... Ic. fruticosus (agg.) ...... v.c.-l.ab. o.-f.c. c.-l.ab. c. idaeus ...... + Salix aurita (damper parts) ... + i.f. r. ? caprea ...... r. 0. o-C. o.-r. cinerea ...... + Sambucus nigra ...... o.-f. f.c. f. + Solanum dulcamara ...... o. o.-r. o. o. Taxus baccata ...... o. r. f.-l.ab. r.r.-o. Tilia cordata ...... o.-r. 1. tntermedia ...... v.r. platyphylla ...... l.r. Ulex europaeus ... r. o. r. ,, gallii ...... o.-l.a. o. o. Ulmus montana ...... r.-o. o.-r. o.-v.c. o.-f. Viburnum lantana ...... - o.-l.f. 1. ,, opulus ...... + f.-c. f. Viscum album ...... r. c. (orchards) Totals 63 40 spp. 42 48 37

The species marked * we do not regard as primarily members of the wood margin flora and this may apply to others not so marked: all those noted have, however, been included as indications of the soil conditions. Geological formations on which the species occur

Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone II Herbaceous species *Achillea millefolium (margin) . . . o. Adoxa moschatellina ...... - r. r. Agrimonia eupatorium ...... - f. + odorata ...... r. Agrostis alba ...... + Ajuga reptans ...... + + f.-c. o.-f. Alchemilla arvensis (path) f. c. + vulgaris (path) ...... I.-o. + + Alliaria officinalis (margin) ...... f. r. f. + Allium ursinum (fluslhes) ...... l.ab. I.f. I.c. Allosorus crispus ...... + Anemone nemorosa ...... l.c. c.-1.ab. c. l.c. Angelica sylvestris (flushes) ... + I.f. + o. 1 Garden escape?

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Geological formations in which the species occur

Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone II Herbaceous species (contd.) Anthoxanthum odoratum ..f. o.-f. ?+ Anthriscus sylvestris (margin) ...+ +- Aquilegia vulgaris .-. -...0. - Arctium nemorosus... .. f.c. + o.-f. f. Arenaria serpyllffolia (margin) -.- +- 99 trinervia (margin) .. .. f.-C + + 0 Arrhenatherum avenaceum (margin) - - f. f. f. f. Arum maculatum (gen. flush) o. 0 I.C f.-C. i.f. Asperula odorata... .. + f.-r. f.-I.ab. o.-f.c. Astragulus glycyphyllos -..-..r. r. Athyrium filix-foemina -. ..+ -r.r. *Avena pubescens.-...-.+ *Bellis perennis (path).....f.-C. f.-C. C. + Blechnum spicant .o..... 0 r - o.-r. *Brachypodium pinnatum (margin) L. If. (1) - o.-1.c. - 99 sylvaticum (margin) o. 0 f. f.-C. f.-C. Bromus asper...... r.r r. o.-f. o. * 9 erectus -.- f.- Bryonia dioica...... r - f. + Calamintha clinopodium (margin) .. f. o.-f. f.-ab. + officinalis ...r.-. - - Callitriche stagnalis (paths) -..-..r. 0. Campanula latifolia +..(1) -..- patula .-. -.....r. 99 trachelium .. .. r. r. o.-f. + Cardamine flexuosa.o. .. 0 (path) o. + -+ 99 impatiens.-.. .+.-..- 99 pratensis (damper pl.) ...+ + + Carduus crispus ...-..+- Carex axillaris.-..+...- flava (flushes) .-. .. -. - 99 goodenovii (flushes) .. ..1.r - hirta.-.- +- pendula (flshes) ..1. . .f. Lab - pilulifera +.. .- ..- remota ..-..0 - strigosa .....1..r. I.r - sylvatica ...... + f.-O. o. Centaurea nigra (agg.) (margin) -.. o. + 99, scabiosa .- -.. ..+- Cerastium glomeratum (path) -..+-- 99 vulgare (path) o. .. 0 + o.-f. + Chaerophyllum temulum (margin) +.- - + *Chlora perfoliata (edge of path) -..v.r. o.-r. r. Chrysosplenium altermifolium (flushes) -r. (1)-- 99 oppositffolium (flushes) 1.f. 1.C r.r. + Circaea lutetiana (damper pl.) o. 0 f.-1.c. f.c. + Cirsium lanceolatum.o.0 o. o. - palustre o. i.f o. + Coichicum autumnale (fushes) -..i.f 1.f.-1.c. L.f. Conopodium denudatum .. .. + f. + f. Corydalis claviculata.....1. c. (3) --- IDactylis glomerata.....+ o. f. + IDeschampsia caespitosa (flushes) .. 1. I.-O. r.r.-1.f. f. flexuosa .-... ..+ -1. Digitalis purpurea.-.. .. c.-f. f.c.-c. r.-o. f. *Diplotaxis muralis .-. -...+- Epilobium angustifolium .. .. ? f.- montanum...... f.-L.c o.-f.c. f. + parviflorum -...i.f. +- Epipctis latifolia...... + + (1) -- Eryhaa centaureum (paths) -.. o r.r. + '9puichella ..- -...v.r. (1) - Euphorbia amygdaloides .. .. f.-c f.-O. I.ab. f.-1.c,

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Geological formations on which the species occur

Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone II Herbaceous species (contd.) Festuca gigantea (margin) ..f. r. o.-r. Fragaria vesca ...... f. f.-ab. c.-L.ab. f.-C. G4agea lutea (flush).. . .- -.- v.r. (1) Galeobdolon luteum ...... f. f.C.-C. f.-C. f. Galeopsis tetrahit. . .+ -.- - Galiumn aparine ...... o0. + + + cruciatum (margin) .. .. r.-o. - . + erectum ...-..+ (1)- mollugo (margin) .. .. + -o.-f. + saxatile (paths) .. .. f.-C. f. r. + verum (margin) --+- Geranium dissectum ....-+- robertianum .. .. f.-f.e. f. f. f. Geum urbanum ..f. + f. + Gnaphalium uliginosum .. ..(path) if. - Habenaria chlorantha...... I.r. 0. Helianthemum vulgare ... r.r. (1) f. Heracleum spliondylium (margin) 0. .-f. + + + Hieracium boreale ....+ + + murorum...... +--- vulgatum ...... - + Holcus lanatus ...L...... Iab. f.c. f.c. +

Hordeum sylvaticum...... -.-1. 1. Humulus ~~mollis ...... lupulus .. c.-f. r....-..ab.-c. f.-c. - 1.ab. Hypericum hirsutum ...... r. r.r. (damp pl.) c.-f. 0 9 huimifusum .. .. + f.-f.c. -- montanum .. .. + r. (1) -- perforatum .. .. o.-f. r.-I.c. f. 0. pulchirum...... 0. o.-f. -f quadratum - .. V.I. - tetrapterum --+ Hypochaeris radicata . ... . -.(path) o. - Inula conyza...... r.r -0. + Iris foetidissima -. -. ..v.r.- Jasione montana ..L. ..if. (1) - Juncus acutus...... (path) 1. -- bufonius +..-..- effusus ..l. . . .f.-- Lactuca muralis ...... 0. o. r.r.--o. *Lamium album (margin) -..-..+- Lapsana communis...... r..- . + Lathraea squamaria ....-..r.( 1) r. (1) Lathyrus montanus ..... + f. o.-r.r. r.-f. pratensis ..-..- ..0.- Listera ovata . . ..-.-.0. + Litliospermum oficinale -.-... Lotus major (flushes) ..... 0. 0. -- *LuzuIa campestris +.. .- -. forsteri ...... o.-l.f. + + ,, maxima ...... + r. (1)-- pilosa .. ... o.-Lf. C. r.r. f.-c. Lychnis dioica...... - 0. + + ~qflos-cuculi ... -1. -r.r Lysimachia nemorum ...... f. f.-c. O.-C. f. Medicago lupulina...... -..0. - Melampyrum pratense ..+ f. + o. Melica uniflora (margin) .. .. f. f. f.c. f.c.-f. Mentha aquatica (agg.) (flushed) - l .f. r.- 99arvensis...... - -0. o.r MVercurialis perennis ...... c.-1.ab. I.c. ab.-c. c.-ab. Milium effusum -. ..r. ILf.-r. r.r. Myosotis arvensis ..... f. + + + umbrosa ... - -.-+

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Geological formations on which the species occur I-~~~~~~~~ Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone II Herbaceous species (contd.) Narcissus pseudo-narcissus .. ..l.C. f.-v.c. r. Neottia nidus-avis . ..- ..r. + + Nepeta glechoma ...... c.-1.ab. o. o.-f.c. i.f. Nephrodium dilatatum .. .. r. r.r.-- .99 filix-mas...... o0. o. o. f. *Onobrychis sativa (margin) ...... +- Orchis maculata ... ..- ..+ o. mascula...... + o. + pyramidalis...... - - . Ori ganum vulgare ...... +- Orobanche major ...... l.r. (1) - - Oxalis acetosella ...... C. v.c.-c. o. f.-V.C. Paris quadrifolia .. - r.r.-I.f. + Pedicularis palustris.. ...1.(1). sylvatica... +--- Plantago major (pathi) ...... 0. Poa annua (path) .. C. C. C. + nemoralis (margin) .. .. C. C. f.--f.c. f.c.-v.c, trivialis ...... r. Le.C. 0. Polygala serpyllacea ...... + r. 11 vulgaris .. -+r Polygonum hydropiper (flushes) ...l.f.-- Polypodium vulgare ...... + -r.r. Polystichum aculeatum i.r. -+ 0. 1) angulare .. Ir.- Potentilla anserina... if. -+ r.r erecta ...... f. f.C.-O. -+ procumbens 1..- ..1 reptans . ...-..f. o. o. *sterilis .. . . f-fec. f. 0. *Poterium sanguisorba...... - -0. Primula acaulis o. . . . O.-C. f.c.-C. f.-v.C. x veris .. .. + -+ + v-enis ...-...+ + Prunella vulgaris ...... + f. C. f.c. Pteridium aquilinum ...... l.c.-ab. l.ab.-f. r.-c. o.-r. Ranunculus auricomus - f. (moist PI.) o.-f. l.f. * bulbosus (margin) --+- ficaria . ... C. l..-.c ab. i.C. flammula (fushs) -..r.r.-- repens (path and flush) .. r.r.-f. L.f. + f. *Reseda luteola .... .-...r. + Rumex acetosa...... v.r. ? acetosella ...... o0. i.f. -- nemorosus...... o0. f. + f. Sagina procumbens (path) -C. - Sanicula europaea . ..l.. .r. 1. (moist p f.c.-ab. C. *Scabiosa columbaria (margin) -.- +- succisa o. . . f. o.-l.c. o.-l.f. f. alba .. .-.-..+ + Scilla nutans...... r.r.-c. c.-I.a. f.-C. f.-l.c Scolopendrium vulgare .. .-. -.-+ Scrophularia nodosa...... o0. o. o. o. Senecio jacobaea . .... - o. -

Sson S, vulgaris amomum ...... (margin) vr. ---..-..r.r. Solidago virg-aurea...... o0. r.r. -- Spiraea ulmaria (flushes) ... l.f.c. l.f. 1.f. Stachys officinalis (margin) .. .. f. f.-O. + f. 99 sylvatica (margin) ..f f. + + StellariLa holostea (margin) o. . . + f. I.e. 9media (path)...... + --+ Stellaria iiliginosa (flushes) - ..1.-

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Geological formations on which the species occur A~~~~~~~~~~~ Malvernian May Hill Wenlock Aymestry Name of species and Uriconian Sandstone Limestone Limestone IS Herbaceous species (contd,) Tamus communis ...... o.-r.r. o. f.-c. r.r. Taraxacum officinale (path) ... + + + Teucrium scorodonia (margin) ... f.-v.c. f.c.-c. c. f.c.-c. Torilis anthriscus (margin) ... o.-t. f. f. f. Trifolium medium ...... + pratense (margin) .. ... + Tussilago farfara ...... r. Urtica dioica ...... f. + o. Verbascum thapsus ...... o. Veronica arvensis (path) ...... + chamaedrys ...... f. f.-c. c. f. montana...... + l.f. (damper pl.) f. + officinalis' ...... l.f. c. o. + serpyllifolia (path) o. f. + Vicia cracea ...... + sepium ...... f. f.c. f. + sylvatica . . . i.f. I.c. Viola hirta ...... l.f. (1) - f. + odorata ...... -. permixta ...... c. (1) riviniana ...... + o.-c. v.c. v.c. sylvestris ...... + 0. v.c. v.c. Totals (Herbaceous species only) 225 spp. 117 148 159 126 Total trees, herbs and shrubs ... 288 157 190 207 163

In the above tables the following symbols are employed, in accordance with the practice of one of us: ab. =abundant; v.c. =very common; c. =common; f.c. =fairly common; f. =frequent; o. = occasional; r.r. = rather rare; r. = rare; v.r. = very rare; 1. = local. The equivalence of these symbols with those used in Types of British Vegetation, etc. is approximately as follows: a. v.c. c. f.c. f. o. r.r. r. v.r.

a. f. o. r. v.r. Where a frequency range is given the first symbol indicates the more usual occurrence. The symbol + is used where the species-- is known to occur but its frequency was not determined. A number in brackets denotes a species which has only been observed in that number of woods of the particular type. Records from the local Floras cited in the Bibliography have been incorporated in the above lists, but unless verified by us no frequency is given. We are also indebted to Mr S. H. Bickham of Ledbury for furnishing us with several additional records from Coneygree Wood.

Woods on the Malvernian and Uriconian rocks. The rocks of the Malvern Hills (Malvernian) are very variable in mineral structure, but extreme acidic' types with much free quartz are rare, and locally considerable masses of distinctly basic rocks' (e.g. potash felspar) occur (Richardson, '05, p. ,8)1. The Uriconian rocks which comprise "rhyolites, andesites, basalts and tuffs " occur locally at Wynd's Point and bear a vegetation essentially similar to that of the Malvernian. The soils of the Hills are mostly light clayey loams, though occasionally a fairly stiff "clay" is met with. The proportion of soluble mineral salts is sometimes at least (p. 25) comparable with that of lowland woods of Quercus robur. The proportion of humus is low and in dry weather the water content may be very low (under 13 per cent.). The existing woods are practically confined to the southern portion of the range. Here Q. sessilijfora is generally the dominant tree, and some of these

1 Cf. the high percentage.? of MgO in Y1-Y4 given in the table on p. 23.

This content downloaded from 128.110.184.42 on Sun, 26 Jun 2016 18:50:06 UTC All use subject to http://about.jstor.org/terms E. J. SALISBURY AND A. G. TANSLEY 31 woods (e.g. the Gullet Wood) are exploited as coppice with standards. Betula alba and flex aquifolium are frequent, the latter being locally abundant. Corylus avellana forms the bulk of the coppice, with Cornus sanguinea and Acer campestre frequent, and Samrbucus nigra occasional to frequent. When we add to this that Fraxinus excelsior is a marked feature of the hills, becoming completely dominant on one flank of Hollybush Hill, that yew and cherry are occasional, and that Clematis vitalba occurs here and there in considerable quantity, it becomes evident that we have scarcely to do 'with a typical Quercetum sessiliflorae. One of the first features that strikes the botanist who imagines that he is on a " siliceous" soil is that ash largely replaces birch as a pioneer tree, and that Betula pubescens is very rare. The ground vegetation presents a similar mixture. While Pteridium aquilinum, Digitalis purpurea and Holcus mollis are among the dominant species, with Galium saxatile, Oxalis acetosella conspicuous, and Blechnum spicant, Carex pendula (flushes), Solidago virgaurea and Corydalis claviculata (local) also associated, we find on the other -hand Mercurialis perennis often dominant, with Holcus lanatus, Euphorbia amygdaloides and Nepeta glechoma, and also such calcicolous plants as Galium cruciatum (o.--r.r.), Hypericum hirsutum (r.), [nula conyza (r.r.) and Viola hirta. With regard to the local ashwood on the Hollybush Hill, we cannot regard this as belonging to the calcareous ashwood series, for its ground flora is practically identical with that of the neighbouring oakwood. It is true that its soil (see p. 23) shows a higher lime content, but this may be partly explained by the fact that the sample was taken to a depth of 6 inches, whereas that from the oakwood represents the surface 2 inches only. It is rather to be regarded as a stage in the succession, perhaps consequent on removal of an earlier oakwood. The ash which, as has been said, is the conspicuous tree pioneer on the hills, is especially -frequent by the paths running down through the oakwood which serve as drainage lines and are readily colonised. Carex pendula (flushes), C. strigosa, Lotus major and Solidago virgaurea are restricted to the Malvernian and May Hill strata.

Woods of the May Hill Sandstone. The May Hill Sandstone gives rise to a distinctly loamy clay which is much stiffer when derived from the upper beds which are partly interstratified shales. The rock is essentially " siliceous " (cf. high resistance, p. 25) and the general soil acidic with a corresponding flora. The species fall into two-categories: (a) plants associated with acid soils, often more or less dry, of which we -may cite Rubus idaeus, Hypericum humifusum, Luzula maxima and Jasione montana (locally frequent in one wood); and (b) plants of damp peaty soil (usually of low acidity), such as several species of Carex, Chrysosplenium alternifolium (one wood), Gnaphalium uliginosum, Pedicularis palustris, Polygonum hydropiper, Ranun- culus flammula and Stellaria uliginosa.

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Betula alba, Salix aurita, Veronica officinalis, Luzula pilosa and Scabiosa succisa are decidedly commoner on the May Hill soils than elsewhere, while there is a decrease of several species of more basic soils,^such as Clematis vitalba, Cornus sanguinea, Prunus &vium, Bromus asper, Festuca g'qantea and Euphorbia amygdaloides. Daphne laureola, Ligustrum vulgare and Galium cruciatum we have not observed on this soil. The markedly "acidic character" of the general vegetation of the steep wooded May Hill Sandstone slopes, which immediately flank the main chain of the Malvern Hills, is thus decidedly altered in the flushes and on the alluvial flats which occur in places (e.g. News Wood) towards the bottom of the slopes. Here we meet with the species mientioned above (b), and here we find such shrubs as Acer campestre, Euonymus europaeus, Cornus sanguinea and Sam- bucus nigra, occasionallv large masses of Carex pendula, and other species characteristic of basic woodland soils, such as Allium ursinum (in abundance recalling the Mountain Limestone and other damp calcareous woods), Angelica sylvestris, Arum maculatum, Circaea lutetiana, Sanicula eur-opaea, Ranunculus auricomus and Colchicum autumnale. These May Hill Sandstone woods show 105 species in common with the Quercetum sessilifiorae of Somerset, and 103 species in common with the Fraxinetum of that county. The former resemblance depends on the vegetation of the steep acidic slopes; the latter on the local more basic vegetation of the moist flushes, hollows and basal flats. Of the series which this area presents the woods on the May Hill Sandstone most nearly approach the typical Q. sessilifiorae.

Woods of the Wenlock Limestone. The Wenlock Limestone forms steeply tilted ridges frequently clothed with woods to their summits. The average slope is steep varying from 1 in 6 to as much as 1 in 3 on the escarpments. The rock itself has a high percentage of calcium carbonate, but the surface soil is often very thoroughly leached (cf. the figures on p. 23), the lime content being reduced to less than 1 per cent. The strong contrast between this leached acid soil, and the highly calcareous soil of some of the steep escarpment slopes (sample B 5) is clearly reflected in the vegetation. The soil is very stiff with a high silt but a low clay (under *002 mm.) fraction. Such soils are well known 'to be refractory to cultivation, and to be excessively dry in summer and wet in winter, since the non-colloidal silt does not flocculate even when sufficient lime is present. The summer dryness accentuates the effect on vegetation of the acidity of the leached soil. Q. robur occurs in these woods with greater frequency than in any of the others examined. Not much stress can be laid on the relative proportions of the two oaks, as some of the pedunculate oak has undoubtedly been planted, but it is noteworthy that on the whole it is most frequent where there is effervescence from the surface soil on adding hydrochloric acid. Q. sessilifiora

This content downloaded from 128.110.184.42 on Sun, 26 Jun 2016 18:50:06 UTC All use subject to http://about.jstor.org/terms E. J. SALISBURY AND A. G. TANSLEY 33 is rarely a dominant tree, and on some of the steep dry slopes neither species of oak is well grown. Much of the Wenlock woodland is coppice with few standard trees, and consists of hazel with a variety of. other calcicolous shrubs. Ash is often abundant in the coppice, and the vegetation of the slopes with a markedly calcareous soil conforms to the ash-oak type (see Types of British Vegetation, p. 181). This is modified in the case of the gentler slopes, where the soil has been strongly leached, in the direction of the more acid type repre- sented by Q. sessiliflorae. The following comparison of some of the Wenlock species which are characteristic respectively of ash-oak (Q. robur) and pure Q. robur woods on the one hand and of Q. sessiliflora woods on the other, illustrates these points. It will be noted that the species under (1) are on the whole more frequent in the Wenlock woods than those under (2).

(1) Fraxinus-Q. robur and Q. robur woods (2) Q. sessiliflora woods

Prunus avium f.--v.c. Pyrus aucuparia r. Ajuga reptans f.-c. Salix aurita r. Arum maculatum f.--c. Digitalis purpurea r.-o. Euphorbica amygdaloides l.a. Galium saxatile r. FPicaria verna l.a. Holcus molli,s f. Iris foetidissima v.r. Lathyrus montanus r.r. Lathraea squamaria r. Luzula pilosa r.r. Milium effusum l.f.-r. Oxalis acetosella o. Primula acaulis f.c.-c. Pteridium aquilinum r.-c. Prunella vulgaris c. Scabiosa succisa 1. Ranunculus auricomus o.-f. Stachys officinalis

It is interesting further to note how closely, both in general composition and in regard to the occurrence of particular species, this Wenlock woodland flora resembles that of the woods containing the two species of oak in Hertford- shire (Salisbury, '16 and '18). In both cases these mixed woods are the home of Pyrus torminalis and Paris quadrifolia. Several species more or less characteristic of Q. sessiliflora woods and occurring in other woods of the area are apparently absent from the Wenlock, e.g. Betula pubescens, Blechnum spicant, Hypericum pulchrum and Potentilla erecta. Other such species exhibit a diminished frequency: Galium saxatile, Holcus mollis, Oxalis acetosella, Veronica officinalis. On the other hand Tilia platyphylla, Juniperus communis, Adoxa moschatellina, Aquilegia vulgaris, Avena pubescens, Bromus erectus, Centaurea scabiosa, Erythraea pulchella, Galium erectum, Helianthemum vulgare, Iris foetidissima, Lithospermum officinale, Orchis pyramidalis, Origanum vulgare, Scabiosa columbaria, Sison amomum, Trifolium medium and Vicia cracca appear to be confined to the Wenlock. Many of these are not primarily woodland plants and others are marginal species. They occur on the wood margins and path-sides where the soil is most calcareous and are largely calcicolo-as species. Though

Journ. of Ecology IX 3

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a non-woodland plant the occurrence here of Brachypodium pinnatum is also significant. Other species, which attain their maximum frequency on the Wenlock, such as Taxus baccata-a marked feature of some of these woods, e.g. Coneygree Wood, Ledbury(Plate II, Fig. 3) and Bank Wood nearWest Malvern-Asperula odorata, Campanula trachelium, Circaea lutetiana, Hypericum hirsutum and Tamus communis are common members of the chalk beechwood flora, while the remainder, such as Ajuga reptans, Holcus lanatus, Melica uniflora, Milium effusum and Prunella vulgaris are more especially found on soils of a neutral or slightly basic character. The distribution of the species characteristic of acid and of basic soils respectively as between different Wenlock woods or different parts of one wood appears to depend very closely on the degree of leaching. It has been pointed out (Salisbury, '20) that "pseudo-calcicolous" species probably occur on calcareous soils because of their dry character, hence such species often find an equally suitable home in the dry type of Q. sessiliflora woods. This tends to diminish the floristic distinctions between woods of this type and ash woods (cf. Table on p. 35). -

Woods on the Aymestry Limestone. The Aymestry rock itself is not so massive a rock as the Wenlock, but largely consists of lines of limestone nodules interbedded with shales. These nodules contain less lime (about 50 per cent.) than the Wenlock (60-70 per cent.), and the soil has a higher proportion of fine particles, especially the silt fraction. Leaching of the surface layers is very pronounced (cf. samples, A 10 and 11 and B 1-4, p. 23), reducing the lime content, as in the Wenlock soils, to less usually than 1 per cent. The Upper Ludlow beds, into which the Aymestry Limestone passes to the west, consist of " micaceous sandstones, in some places highly argillaceous, others equally calcareous" (Richardson, '05, p. 21), and the low lime content of the soils of parts of these wooded hills no doubt depends partly on this fact. The physiographic features are similar to those of the Wenlock-steep wooded ridges, but rather more cut up by transverse valleys into isolated summits, sometimes 700-800 feet high. The soil type and vegetation are very similar also. The woods are largely coppice, as on the Wenlock, but Q. sessil?ftora is distinctly commoner, while ash and yew are on the whole less prominent, and so, in general are the characteristic "calcicole" shrubs. There are few species occurring on the Aymestry and not on the Wenlock, but of these Ulex europaeus and U. Gallii (margins of woods), Hypericum pulchrum, Potentilla erecta, Alchemilla arvensis and Blechnum spicant point in the same direction. Prunus cerasus appears to be confined to the Aymestry among this series of woods. Digitalis purpurea also shows an increased prevalence as compared with the Wenlock, and the list of markedly calcicolous species given above as confined

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to the Wenlock further emphasises the less calcareous nature of the habitats presented by the soils of the Aymestry Limestone. On the other hand, the following species, which are found on Aymestry and Wenlock alike, and not on the May Hill Sandstone or the Malvernian, bear witness to the limestone basis of the soil:

Tilia cordata Lathraea squamaria Daphne laureola Paris quadrifolia Viburnum lantana Primula veris and hybrids Astragalus glycyphyllos Vicia sylvatica HordeuM sylvaticum Viscum album has been recorded by Lees in the district on hawthorn, maple, lime, ash, willow, mountain ash, service, white poplar, aspen, elm, hazel and oak. It is specially abundant on apples and pears in orchards, and is a marked feature of the Wenlock and Aymestry alike, also of the calcareoue Keuper marls of the Worcester plain. Laurent ('00) has shown that mistletoe grows more freely on calcareous soils. One of us has seen it on Q. sessilijiora in Cother Wood and on Q. robur on the Ridgeway. The actual distribution of calcicolous and calcifuge species depends again upon leaching. Thus the abundant Holcus mollis occurring on the ridge of Rowburrow wood, where the lime content is as low as 043 per cent., contrasts with the prevalence of such species as Mercurialis perennis, Scilla nutans and Primula acaulis, abundant on the slope where the lime content varies from 0-65 to 1-43 per cent.

Comparison of Malvern and Somerset Woods. Oak-Hazel Q. sessiliflora Woods Ash Woods (Q. robur) Woods (a) Number of species from Malvern Woods of Trees and all types found in each type of Somerset shrubs 30 23 31 Wood ...... Herbs 83 82 96 (Malvern Woods, 63treesandshrubs,herbs225)J Totals 113 =39% 105=36% 127 =44%

(b) Number of species from Malvern Woodsl Trees and other than those on Wenlock Limestoned Herbs 83 76 86 found in each type of Somerset Wood ... H J Totals 111 =43% 99=38% 116 =45% (c) Number of species present in the Wenlock Trees and Limestone woods in the different types of shrubs 26 23 29 Somerset Woods ...... Herbs 67 70 83 Totals 93 =44% 93 =45% 112=54%

(d} Number of species present in the woods onI Trees and May Hill Sandstone in each type of Somer-? shrubs 27 20 27 set Wood ...... Herbs 78 69 76 Totals 105=55% 89 =46% 103 =54%

Succession. In established and partly artificialised vegetation like most of the English woodlands, it is not easy to discover unmistakeable evidence of succession. On general grounds, however, we may suppose that leaching of soils is 3-2

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a progressive factor which would gradually tend to change the vegetation of the soils in general from a more basic to a more acid type. There is evidence (C. G. Hopkins, Ill. Agr. Exp. Sta. Bull. 123, 1908) that this process may extend over very considerable periods. We may thus perhaps conceive of the Malvern limestones as having been originally dominated by ash, with its accompanying calcicolous flora, and that as leaching and humus accumulation progressed the ash-woods were invaded by the durmast oak which evexntually became dominant over most of the area; the ash (which is now always coppiced on the limestones) remaining abundant only on the steep escarpments where fresh soil is constantly exposed and humus accumulation is retarded. The durmast oak was accompanied by a number of species of moderately acid soils, though the conditions have not become sufficiently extreme to lead to invasion by plants like Calluna and Vaccinium. With regard to the occurrence of Q. robur it is difficult to know how much importance to attach to its distribution owing to the uncertainty in regard to planting, but it may be suggested that the soils are largely too dry to favour a general invasion by this tree. An interesting secondary succession is suggested by a remark of Lees ('67, p. xvi). "I have noticed," he writes, "within the last 30 years in our Worcestershire woods, as well as in those of Herefordshire, a great increase in the quantity of wild cherry trees (P. avium) and this especially after a fall of the indigenous coppice.... In old undisturbed woods the cherry is scarcely to be found." The effect of coppicing in producing a rapid decrease in humus, accompanied by a rapid rise but subsequent decrease in acidity has been shown elsewhere (Salisbury, '16, p. 114, '18, p. 40). Such an effect would tend to be accentuated by the basic character of the subsoil, and thus periodic coppicing may have brought about a greater frequency of calcicolous species than would have existed in untouched woodland. After each coppicing such species may become established before the surface soil regains its former acidity, and thus the natural tendency of the woodland soil to increase in acidity is retarded to a degree which varies inversely with the period of rotation.

Vegetation of non-vascular plants. With respect to this we have only paid attention to the Bryophytic Flora, and this not sufficiently in detail to justify our giving lists of species. But for all the woods the Bryophytic Flora seems to be rather poor. The general relation noted elsewhere (cf. Salisbury, '16, p. 111 and '18, p. 42) as between Q. robur and Q. sessiliflora woods, seems to obtain here when we compare the woods of the Malvernian and May Hill Sandstone with those on the limestones. For both mosses and liverworts appear to be more prevalent-in the former than the latter. Mollusca. Prof. A. E. Boycott has kindly determined for us a small collection of mollusca gathered from the Ridgeway and Coneygree and Cother Woods

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(WenlockLimestone) made partlyin spring and partlyin autumn. This collection turns out to be more or less intermediate, as regards the number of species involved, between the large molluscan fauna of a calcareous beech-wood and the restricted list of species obtainable from an acid oak-wood (cf. Salisbury, '18, p. 47). The following are the species: Arion ater Helix aculeata Hyalinia fulva hortensis ,, hispida ,, helvetica Limax arborum ,, rotundata ,, nitidula pygmaea ,, pura Acanthinula aculeata Hyalinia alliaria ,, radiatula Clausilia laminata ,, cellaria Vertigo edentula Cochlicopa lubrica ,, crystallina Vitrina pellucida Cor?ychium minimum

GENERAL. Of the 63 trees and shrubs and the 225 herbaceous species here listed the great majority (viz. 77Y5 per cent. of the former and 85-4 per cent. of the latter) are normally present in the Quercetum sessiliflorae. Although Q. sessiliflorae is, or may be, dominant on the soils derived from all the four rock-types described, we are only dealing with a typical Q. sessiliflorae in the case of the May Hill Sandstone. The oak-woods of the Malvernian show a marked admixture of more basic species, while the Aymestry and Wenlock Limestones present transitions between Fraxinetum excelsioris and Q. sessiliflorae, in which one facies or the other preponderates according to the lesser or greater degree of leaching. In the case of the Wenlock especially, there is also a distinct affinity with Q. roburis. This conclusion is borne out by a comparison of the number of species of the different types of Malvern wood occurring in the three types of Somerset wood distinguished by Moss ('07). The May Hill Sandstone woods show the greatest resemblance to the Q. sessiliflorae of Somerset. The number of May Hill species found in the Somerset ash-woods is nearly as high but this is augmented by the inclusion of flush and alluvial species which are more characteristic of basic soils. The Wenlock Limestone on the other hand shows the greatest number of species in the Somerset ash-woods and distinctly fewer (about equal numbers) in the Somerset woods of durmast oak and "oak- hazel" (ash-oak). The presence of Q. sessiliftora and its associates on soil derived from calcareous rocks is thus not inconsistent with the predilection of this tree for acid soils, especially when we remember that the conditions met with during the seedling stage are probably the most important in determining establishment, and that it is precisely the surface soil in which leaching is most marked. Finally our examination of these woods has emphasised the necessity of making actual soil analyses and tests before drawing conclusions as to the.

This content downloaded from 128.110.184.42 on Sun, 26 Jun 2016 18:50:06 UTC All use subject to http://about.jstor.org/terms 38 Querceta sessiliflorae near Malvern

edaphic factors of the habitat. Not a few writers have based their discussions of the distribution of calcicole and calcifuge species on the assumption that calcareous rocks always give rise to calcareous soils. As we have shown this assumption is completely etroneous and the occurrence of Q. sessiliflora on soils overlying calcareous rocks is in no way inconsistent with the general features of its distribution.

LITERATURE REFERRED TO. (a) LocAL. Botanical. Amphlett, J. and Rea, C. The Botany of Worcestershire. Birmingham, 1909. Lees, Edwin. The Botany of Worcester. Worcester, 1867. Lees, Edwin. The Botany of the Malvern Hills. 3rd ed. London, 1868. Leighton, W. A. Flora of Shropshire. London, 1841. Ley, Rev. A. "Additions to the Flora of Herefordshire." Trans. Woolhope Nat. Field Club, 1894. Ley, Rev. A. "Notes additional to the Flora of Herefordshire." Trans. Woolhope Nat. Field Club, pp. 69-152, 1905. Purchas, Rev. W. H. and Ley, Rev. A. A Flora of Herefordshire. Hereford, 1889. Victoria History of Herefordshire (ed. by W. Page), vol. 1, London, 1908. Geological. Groom, T. T. "The Geological Structure of the Southern Malverns and of the adjacent district to the West." Q. J. Geol. Soc. 55, pp. 129-169, 1899. Groom,T. T. "On the Geological structure of portions of the Malvern and Abberley Hills." Q. J. Geol. Soc. 56, pp. 138-197, 1900. Phillips, J. Mem. Geological Survey, 2, pt I. 1848. Richardson, L. "An outline of the Geology of Herefordshire. Trans. Woolhope Nat. Field Club, pp. 1-68, 1905. Meteorological. Bickham, S. H. "Local Rainfall for the past 20 years." Trans. WVoolhope Nat. Field Club, p. 245, 1901. (b) GENERAL. Armitage, E. "Vegetation of the Wye Gorge." This JoURNAL, 2, 1914. Hopkins, C. G. "The Soils of Illinois." Illinois Agr. Exp. Sta. Bull. 1908. Laurent, E. "De l'influence du sel sur la dispersion du Gui et de la Cuscute en Belgique." Bulletin dl Agriculture, 1900. Moss, C. E. "Geographical Distribution of Vegetation in Somerset." Roy. Geog. Soc. London, 1907. Salisbury, E. J. "The Oak-Hornbeam woods of Hertfordshire," Pts i and ii. "The Quercus robur-Carpinus Woods." This JOURNAL, 4, pp. 83-117, 1916. Salisbury, E. J. "The Oak-Hornbeam woods of Hertfordshire," Pts in and iv. "The Quercus sessiliflora-Carpinus Woods." This JOURNAL, 6, pp. 14-52,-1918. Salisbury, E. J. "The effects of coppicing." Rep. British Ass. 1914. Salisbury, E. J. "Photographic studies of Welsh Vegetation." Proc. Linn. Soc. p. 3, 1916. Salisbury, E. J. "The Significance of the Calcicolous habit." This JOURNAL, 8, pp. 202-215, 1920. Tansley, A. G. in Hampstead Heath, its Geology and Natural History. "Vegetation," pp. 85-111. London, 1913. Tansley, A. G. (ed.). Types of British Vegetation. Cambridge, 1911.

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