217 



As stated on p. 178 the steep wall of the rupture bore in 1908 

 already many plants. The beach at Zwarte Hoek consists, as was 

 already mentioned on p. 145, of 2 oecologically very different parts, 

 the beach proper bearing halophilous plants and the old leached-out 

 parts with a halophobous vegetation. Between these two Mr. Docters 

 van Leeuwen does not distinguish. It would be of interest to 

 compare the vegetation of 1906 and 1908 with that ef 1919, but a 

 list of all plants found at Zwarte Hoek in 1919 not having been given, 

 this is impossible. We are only told that there were ,,all sorts of 

 ,, littoral plants", a popular statement such as one would scarcely 

 expect to find in a scientific paper on the development of a new 

 vegetation. Spinifex was collected at Zwarte Hoek already in 1897 

 and on most or all subsequent excursions (See pp. 89, 146, 179). We 

 are not told whether the thick brushwood mentioned consisted of 

 littoral plants growing near the floodmark or of non-littoral plants 

 growing farther back. But in this brushwood the only (' ; ) specimen 

 of Cycas rumphii was found that was seen in April 1919. In the 

 Transactions of the Congress no further data are given about the 

 habitat of this specimen but in a subsequent paper ') we are 

 informed that this female plant was growing immediately behind the 

 beach-vegetation ,,near the cone of tumbled stones and masses of 

 ,,ash" -) and that it was quite conspicuous. It (its trunk ?) was 1,20m. 

 high. Another specimen, a male one, was discovered in October of 

 the same year near the y one; it ,, flourished more under the trees" 

 and (its trunk ?) was 0,95 m. high. This rather large specimen had 

 apparently been overlooked in April, which proves how carelessly the 

 investigation in that month had been carried out. Both specimens 

 possessed stems rising upright from the base. This is considered by 

 Mr. Docters van Leeuwen proof that the growth of Cycas 

 is not slow. Cycas is, under cultivation, indeed a very slow grower 

 (see pp. 130, 131) but we know nothing at all about the velocity of 

 its growth in its natural habitat: the sea-shore and the localities not 

 very far from it. Mr. Docters van Leeuwen says 1 ) ,,that it is 

 ,,difficult to believe that this pair of robust plants should have sprung 

 ,,from pieces of trunk washed ashore". This unbelief is rather unfounded. 

 The trunk of Cycas rumphii very often produces lateral shoots. 



1 ) Dr. W. Docters van Leeuwen. The vegetation of the Island of Sebesy, 

 situated in Sunda-Strait near the islands of the Krakatau-group; in the year 1921, in 

 Ann. |ard. Bot. Buitenzorg XXXII (1923), p. 138. 



-) It seems that Mr. Docters van Leeuwen means the large talus of ashes 

 bordering the beach of Zwarte Hoek on its south-eastern extremity. 



