The Vessel in Seed Plants

Abstract

1. In Pteris the scalariform perforation of the vascular end wall often becomes pitted. 2. In the Gnetum type of vessel the fusion of pits to form the porous perforation is haphazard, but in Gnetum scandens the fusion of pits is often more regular, resulting in a scalariform perforation. 3. Haphazard fusion of pits is also found in Paeonia, Cydonia, and Leea; while in Liriodendron, Magnolia, Paeonia, Betula, Alnus, Quercus, and Vitis the fusion is often serial, resulting in scalariform perforations. 4. The evolution of the perforations of the vessels in Gnetales and Dicotyledons is similar, and in both cases is the result of pit fusions. 5. From evidence derived from a consideration of primitive and conservative regions in Liriodendron, Magnolia, Paeonia, and Vitis, it may be concluded that the primitive type of vessel in the Angiosperms is pitted, and has been derived from the pitted tracheid as have the mechanical and longitudinal storage elements of the wood.