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SEA-SIDE PLANTS. 



BEING THE SUBSTANCE OF AN ADDRESS DELIVERED 

 AT CANVEY ISLAND, JUNE 15th, 1901. 



By PROF. G. S BOULGER, F.L.S., F.G.S., V.P.E.F.C. 



Although not myself a total abstainer, I can feel for the 

 inhabitants of this island, animal and vegetable alike, who may 

 be said, in the words of the poet, to be surrounded by 

 " water, water everywhere, 

 Nor any drop to drink." 

 As we have walked along the sea-wall and beach we have noticed 

 a variety of flowering plants, members of several widely differing 

 Natural Orders, which agree in the common property of succu- 

 lence, succulence both in stem and leaf, accompanied for the 

 most part by a smooth surface, and in some cases by a blue- 

 green waxy " bloom." The Marsh Samphire or Glass-wort 

 {Salicovnia herbacea), the Sea.-h\ite (Sua da viaritiiiia), a.nd the Crab- 

 weed (A triplex povtulacoides), which grow on the " saltings," 

 where they are overflowed at high tide, are, it is true, members 

 of one Order, the Chenopodiacece ; but the Yellow Horned Poppy 

 [Glaucium flavum) , the Stone-crop (Sedum acre), which we found 

 so luxuriant, the Sea Sandwort [Alsine marina) and the variety of 

 the Carrot [Daiicns carota, var. gummijcr), which occur a little 

 farther inland, belong to very diverse groups ; yet all agree in 

 these outward characteristics, as do many other sea-side plants, 

 such as the Sea- Kale (Craiiibe niavitima), which we have not come 

 across to-day. If we examine the structure of these plants 

 microscopically we shall find that this succulence is largely pro- 

 duced by a thick, almost leathery outer wall to the epidermal 

 cells and the presence of a large amount of water (salt-water) in 

 the internal cellular tissue, while it is accompanied by a very 

 small number of stomata or transpiration-pores. This thijk 

 impermeable cuticle and this internal store of water are precisel}' 

 similar to the structures that we find in desert plants We have, 

 in fact, in these plants growing close to the water's edge special 

 adaptations to check transpiration, to economise water. Why is 

 this ? A familiar laboratory experiment throws light upon the 

 question. If we place a thin section of fresh beetroot — a plant 

 of sea-side origin, by the way — under the microscope and bathe 

 it with a 5 per cent, solution of salt, we find that the red proto- 



