40 THE DISTRIBUTION OF EAST RIDING PLANTS. 



Calluna vulgaris, Erica Tetralix and E. cinerea, Pyrola minor, 

 Scleranthus annuus, Rumex acetosella, Pinus sylvestris, 

 Goodyera repens, Juncus squarrosus, Aira prcBCOx, Aira 

 (Deschampsia) flexuosa and A. flexuosa, Nardus stricta 

 Molinia varia, Lastraea cristata, and Botrychium Lunaria, 

 It is somewhat remarkable that no ericaceous plant except 

 Monotropa affects the Wolds, whilst Holderness has only a 

 single station for common heather. The sandy commons 

 afford the only true heaths, and chiefly common heather 

 (Calluna). 



IV. The Wolds (chalk) have a very well marked 

 association, again of xerophilous plants, but of such as in 

 Yorkshire are rarely found off one form of limestone or 

 another. Many of them are larger xerophiles with rough 

 hairiness or wooUiness. The group contains Clematis 

 Vitalba, Papaver dubium, P. hybriduni. Reseda lutea, Heli- 

 anthemum vulgare, Viola hirta, Linum perenne, a single 

 species of Saxifrage (S. tridactylites). Spiraea Filipendula, 

 Poterium Sanguisorba, Centranthus rubra (which during the 

 summer festoons in crimson the disused chalk-pits at Hessle), 

 Sanicula europeea (in other places so much affecting clayey 

 situations is the commonest plant in woods on the chalk), 

 Scabiosa Columbaria, Senecia erucifolius, Carduus eriophorus, 

 Picris hieracioides, Crepis biennis. Campanula rapunculoides, 

 C. glomerata, Monotropa hypopitys (parasitic on mould or 

 fungus investing roots of the Beech), Chlora perfoliata, Atropa 

 belladonna. Origanum vulgare, Calamintha clinopodium, 

 Galeopsis Ladanum, Plantago media (also on the oolitic lime- 

 stone outcrop), Fagus sylvatica, Epipactis latifolia, Orchis 

 pyramidalis, and Ophrys apifera. The most characteristic 

 grasses are Milium effusum, Brachypodium pinnatum, 

 Festuca sylvatica, Bromus scuiroides, and Avena pubescens ; 

 whilst the Oak Fern (Phegopteris Dryopteris) is known only 

 in one station in the East Riding, and that is on the chalk. 



