Botany. — “On the Caleifuge Plants of the Inland Dunes of the 
Island of Goeree”. By Dr. Tu. Weevers. (Communicated by 
Prof. Went). 
(Communicated at the meeting of May 29, 1920). 
The broom, Sarothamnus vulgaris Wimm, occurs in the island of 
Goeree within a sharply defined area. This fact first induced me 
to examine the flora of the grounds where the broom occurs and 
where it does not; afterwards I was led to study that flora in con- 
nection with the nature of the soil. 
This research concerned especially the interior of the island, known 
as the “Oude Land van Diepenhorst’, which is bounded by the 
Western-Dunes in the West and the Central- and Eastern-Dunes in 
the Hast, the latter bordering on the young Sea-dnnes; the old center 
being for the rest surrounded by polders. Lori *) had already looked 
upon this center as the old inland-dunes; the small calcium-content 
of the sandy soil, less than 0.07 °/, CaCO, ’) lends support to this 
~ conception. 
Yet these inland-dunes cannot be put on a par with the inland- 
dunes to be found north of the Meuse. From data derived from 
borings, performed’) with a view to the construction of a tramway 
and to the watersupply of the island, it appeared to me that under 
the layers of sand are always found bands of bog-, and clay-soil, 
whose upper edge lies 1 m. below A. P. (Amsterdam water-mark), 
the lower edge from 2 to 5 m. below it, approximately at the same 
level where these layers are found also in the other parts of the 
island of Goeree and Overflakkee and likewise in Zeeland. So the 
inland dunes of Goeree are overlying peat-, and clay-layers of the 
old “haff”, as in Belgium, and not the old “Schoorwal”. But the 
Goeree inland-dunes are poor in calcium unlike most of the Belgian 
dunes, which are calcium-rich. Consequently their flora bears a marked 
resemblance to that of the few calcium-poor districts found in Zee- 
land and in Belgium, and termed by Massart *), in agreement with 
Ruror ®), the ‘dunes internes’”’ and “sable a Cardium’”’. 
DJ. Lorié, Arch. du Musée Teyler. Vol. III. 1892. 
2) Cf. Jeswier, Entwicklungsgeschichte der Flora der holländischen Diinen. 
5) These data were procured through the kindness of Dr. J. T. Sreenuuis. 
t) J. Massart, Essai de geographie bot. des districts litt. et alluv. de la Belgique 
Recueil Inst. bot. L. Errera, T. VII. 1908. 
5) A. Rurot, Bulletin de la société de géologie, paleontologie et d’hydrologie 1906. 
