THE AZORES 



421 



Cakile edentula. — The upper joints of the fruits float for nine 

 or ten days. Probably introduced in ballast from America (see p. 189). 



Crithmum maritimum. — The original flotation experiments in 

 sea-water covered ten months, 95 per cent, of the carpels remaining 

 afloat (O). They were subsequently extended to thirteen months, 

 when 90 per cent, remained afloat, a few of which germinated in 

 soil two months later. 



Euphorbia azorica. — The seeds float in sea-water from one to two 

 weeks, but the water soon penetrates their coats. In the case 

 of E. peplis he has no data; but the floating powers are probably 

 limited. 



Hyoscyamus albus. — The seeds sink. 



Ipomcea carnosa. — The seeds float unharmed in sea- water for twelve 

 months and more and germinate afterwards (see p. 218). 

 J uncus acutus. — The seeds sink. 

 Plantago coronopus. — The seeds sink. 



Polygonum maritimum. — The nutlets sink in sea- water, but en- 

 closed in the perianth they float three or four days. The entire 

 plant, or branches of it, would float five or six days when carried off 

 a beach by the waves (O). 



Salsola kali. — Enclosed in the perianth the fruit floats in sea- water 

 for a few days, but when detached it sinks. Portions of the plant 

 bearing mature fruits float at first, but sink within ten days (O). 



Samolus voter andi. — The seeds sink (O). 



Silene maritima. — Seeds sink (O). 



Solidago sempervirens. — No data, but prolonged buoyancy is 

 unlikely. 



Spergalaria marina. — Seeds sink (O). 



Of the fifteen shore plants above named only two, Crithmum 

 maritimum and Ipomcea carnosa, can be regarded as adapted for 

 transport by currents to the Azores. Nearly half of them have 

 small seeds, namely, the species of Hyoscyamus, J uncus, Plantago, 

 Samolus, Silene, and Spergularia. It is not unlikely that the seeds 

 of the Hyoscyamus, Silene, and Spergularia, are carried in the crevices 

 of drifting logs. But sea-birds are also able to assist in the distri- 

 bution of these small seeds. Gulls, for instance, often make their 

 nests on the faces of cliffs in the midst of a dense growth of Sea- 

 Campion {Silene maritima) ; and it would be surprising if they did 

 not aid in the distribution of this plant. Still more likely would 

 this be with Plantago coronopus, which grows on the rock-ledges 

 where these sea-birds nest. Here the seeds emit mucus and become 

 sticky when wetted, and they would adhere firmly to a bird's plu- 

 mage when dry. The small seeds of Samolus valerandi have been 

 found in mud adherent to birds; and the frequent growth of the 

 plant in wet places by the sea would afford opportunities of this 

 occurring (Kerner). The prickly pointed leaves of Salsola kali would 

 enable bits of the plant carrying fruits to catch in feathers as readily 

 as they do in one's clothes. Many granivorous birds are fond of 

 Polygonum nutlets, which are often found entire in their stomachs ; 

 and doubtless birds frequenting beaches would swallow the seeds 



