64 



aiireum L., Cynanclium carnosum Sc/i/echt., Diplachne po/ystachya 

 Backer, - G-ymnanthera pa/iidosaSchtim., - Paspahint vaginatumSwartz, 

 Scirpus littoralis Sc/irad., - Xerochloa imberbis R.Br.) may thrive. Besides 

 littoral species and such halophytes as occur also in the interior, one 

 finds on broad beaches, especially on their older less saline or quite 

 leached-out parts, a considerably large number of plants which may 

 also be found in the interior in not salt localities. T r e u b, who 

 examined only a small part ') of the then still very young beach of 

 Krakatao, found there already such a plant of the interior (Pennisetum), 

 whilst, on the contrary, he mentions some typical plants of the coast 

 (Tournefortia argentea L. fit. and Wedelia biflora D.C.) for the interior 

 only (,,la montagne proprement dite"). This does not warrant the 

 conclusion that Treub by the plants found by him has proved the 

 incorrectness of his statement, for he was no florist and may have 

 misremembered. Moreover it is not certain that he, who was no 

 phyto-geographer, has taken the word beach in its oecological 

 sense. It often occurs in the tropics that localities, which verge on 

 the beach but which by some cause f.i. by a higher situation or a 

 too great age, considerably differ from it, yet are considered as 

 such by inexperienced collectors and Treub may have made the 

 same mistake. After what I have remarked on pp. 5 and 6 about 

 young vegetations in the tropics it need scarcely be said that on 

 the eastern beach of Krakatao, which was not examined by Treub, 

 many species may have grown which were not found by him at 

 Zwarte Hoek. The same holds good for the interior of Krakatao. 



2. // is beyond doubt that the fruits of the 4 Compositae have 

 been carried over to Krakatao by \vind. 



This conclusion is apparently not based on observations or on 

 experiments but is a mere supposition. Hence it cannot furnish proof 

 for any hypothesis but only increases the number of unproved guesses. 

 The first of the Compositae found by Treub, Wede/ia biflora D. C., 

 is a common littoral plant, occurring also along rivermouths. As I 

 have already said on page 50, it possesses rather large fruits without 

 a pappus but with a thick pericarp developed into a floating 

 tissue, a fact which must have been unknown to Treub. This species 

 was certainly not introduced by wind but most probadly by the sea. 



') On the western and the southern side of Krakatao the coasts of the island are 

 very steep, on the south-eastern and eastern side a well-developed beach is present 

 over a length of abouth 3"'/i km. The beach of Zwarte Hoek is + 750 m - long. 

 I his latter beach only was examined by Treub, consequently not yet 17% of the 

 entire beach. Of the interior he examined only a very small part. 



