Les caracteristiques de l’exine chez quelques especes de Quercus

The characters of the exine of the following Quercus species are discussed; Q. petraea, Q. robur, Q. pubescens, Q. ilex and Q. coccifera. As regards the construction of the exine two types can be distinguished, a type A (Q. petraea-robur-pubescens) and a type B (Q. ilex-coccifera). These two types differ in the relation between the height of the scabrae and the thickness of the tectum and also in the relation between the largeness of the scabrae and the largeness of the columellae. In type B the scabrae are lower in comparison with the tectum; and the columellae are larger in comparison with the smaller scabrae. A division of the genus Quercus in pollenmorphological types appears to correspond most with the system proposed by Schwarz in his monograph of the European and Mediterranean Quercus species.