THE DISTRIBUTION OF EAST RIDING PLANTS. 37 



(c) Marshes, carrs, and ings (damp grassy fields) on the 



clay or clayey alluvium of Holderness. 



(d) Marshy and boggy places in Derwentland, being 



sandy alluvial tracts, and marshy places adjacent to 

 springs at the foot of the Wolds. 



{e) Fields, woods, and lanes of Holderness. 

 {/) Fields, commons, lands, woods, &c., of Derwent- 

 land. 



Observation of these habitats in order reveals the following 

 characteristic groupings : — 



In {a) the vegetation is, of course, hygrophilous (aquatic 

 in a high degree), or sub-h)'grophilous {i.e., aquatic to such 

 a degree that if not actually growing in water it is not far 

 from it). In the waters of the rivers, streams, canals, and 

 larger drains, often nearly adjacent to the Humber Estuary 

 already described, grow the true hygrophiles ; on their banks 

 and the muddy places adjacent are the sub-hygrophiles. 

 Smoothness of external parts, an almost entire absence of 

 hairiness, and an internal sponginess of tissue (lacunar tissue) 

 are marks of hygrophilous plants. For many reasons the 

 hygrophiles are of very great interest indeed. Their habitats 

 being less liable to interference by man, they remain certainly 

 the descendants of the more primitive members of our flora. 

 The following group is not exhaustive : — Thalictrum flavum. 

 Ranunculus circinatus, Nymph^a lutea, Castalia speciosa. 

 Nasturtium amphibium, Hippuris vulgaris, Ceratophyllum 

 demersum, Alisma Plantago, Sagittaria, Butomus, Polygonum 

 rufescens, P. lucens, all except the first, true aquatics; whilst 

 Thalictrum and the sedges, Carex vulpina, C. rostrata, 

 C. paludosa, and the grasses Glyceria aquatica and Phalaris 

 arundinacea, are sub-hygrophiles. 



{b) Dykes, and muddy places adjacent thereto, together 

 with ponds and larger natural ponds or meres, have an 

 association of plants quite distinct from that held by the 

 waters of the preceding. If one may give the group a 

 special name it would surely have reference to the Batrachian 

 Ranunculi (Water Crowfoot), the predominant plants. The 

 association includes Ranunculus Drouetii, by far the com- 

 monest form, R. peltatus — of many varieties and forms, 

 e.g-., floribundus and truncatus — R. Baudotii, which affects 

 brackish water (and most dykes adjacent to the Humber in 

 low-lying Holderness are brackish), R. sceleratus, R. Lingua, 



