167 



Asclepiadaceae. 



12. Cynanchum /aeve Schum. (C. Blumei B. et H.). 



Twiner, found in West-Java in several localities between 20 

 and 1000 m. above sea-level on forest borders and in thickets. 

 The reproduction is effected by the comose seeds which over 

 land may be easily spread by the wind over some distance. 

 The ripe seeds very easily let loose from the tuft of hairs. 



A fruiting specimen collected in 1906 by Ernst on or 

 near the beach of Krakatao ') is preserved in the Buitenzorg 

 Herbarium. As flowers are lacking the determination is not 

 quite certain. 



At the end of his description of the excursion of 1906 Ernst 

 gives a list of all plants found till that year on the 3 islands of the 

 Krakatao-group. Recording a few of these under different names twice 

 or even three times he comes to a total of 137 species. Among 

 these are 108 Phanerogams and Vascular Cryptogams of which 67 were 

 found exclusively or mainly on the beach, the others in the interior. 

 After making the necessary corrections and adding the plants found 

 in 1905 by Valeton I come for Krakatao itself to 119 species, of 

 which 90 are Phanerogams or Vascular Cryptogams. Among these 

 are 39 or 40 littoral species and halophytes, the 50 others are 

 plants of the interior ~). 



It is clear that in drawing conclusions from a comparison of the 

 vegetation of Krakatao in 1905/1906 with that of 1897, all plants 

 should left out of account which were found on the south-eastern 

 side which was never visited by a botanist before 1905 and likewise 

 all plants of which the habitat is unknown. On the other hand it 

 should not be forgotten that in 1897 the slopes above Zwarte Hoek 

 were investigated up to a not inconsiderable height whilst in 1905 

 Valeton went only some short way up; in 1906 these slopes, their 

 very base excepted, were not explored at all Doubtless this is one 

 of the causes that several plants, collected at former excursions, 

 were not found back in 1906. For instance, in 1897 the number of 

 ferns observed was 13, in 1906 but 5, among which not a single 

 new one. From this fact may only be concluded that the exploration 

 in 1906 was not sufficiently intensive. There is only one part of the 



*) Ernst, Neue Flora Vulkaninsel Krakatau (1907), p. 47. 



2 ) One should not forget that on unstable coasts like that of Krakatao it is often 

 difficult to clearly distinguish between beach and interior (taken in the oecological 

 sense of the words). 



