Morphology, Stucture, Development And Systematics Of Euptelea (Eupteleaceae)

Eupteleaceae is a monogeneric family, endemic to East Asia with the only genus Euptelea that is a genus with 2 species. The systematic position of Eupteleaceae has been disputed for a long time. Many features of Euptelea pleiospermum in china were described in the present paper. Including the variation of perforation plate of vessels in the stem , the pit membrane remnants in the perforation plate of vessels, Anatomical Studies on vegetative organs, flora morphogenesis, pollen . We attempted to supply some new features on the determination of the systematic position of Eupteleaceae. 1 The variation of perforation plate of vessels in the stemthere are two types of vessels in the secondary stem of E. pleiospermum, one is the tracheid-like vessels and another is typical vessels. In the tracheid-like vessels, the perforation pits are large than that of in the lateral-wall of the elements, arranged irregularly and do not form the obvious morphology of the perforation plate and the membrane of the perforation pits disappears completely or partly. In the typical vessels, the perforation plates are diversiform. The perforation plates of the typical veseels could be divided into following subtypes: The reticulate perforation plate (including the foraminate ones), the reticulate-scalariform perforation plates in which the perforation pits are arranged in reticulate and scalariform in the same perforation plate, the scalariform perforation plates in which the multiple-scalariform perforation plates are often observed, scalariform-simple perforation plates and some other perforation plates could not be divided into anytype. Multiple end-wall perforation plates and the lateral-wall perforation plates were also observed in the secondary wood of the species. The pit membrane remnants are abundant and there exist the continuous transform between the pits with complete pit membrane and that with the pit membrane disappeared completely.2 Anatomical StudiesThe primary structure of root is diarch. The rays in the secondary structure are heterocellular. The vascular bundles are ring arranged in the primary stem, and the rays in the secondary wood are homocellular. The rays in the root and stem are not parallel. The node is unilacunar and 5 traced in the beginning and the lateral bundles can divide repeatedly to form 7-9 bundles before the traces inter the petiole. The cells of the leaf pyidermis are irregular and the stomatal apparatus or occasionally ranunculaceous type.3 Morphogenesis of FlowersNo Metanaphytosis. The stamina and pistils are spiral initiation. But the stamina bidirectional spiral in a whorl, while the pistils are anticlockwise spiral. 4. Modality of pollenAperture of pollen is colpus or porus. Most are pollens of four porus (colpus), and a few are pollens of five porus (colpus) or three porus (colpus). 6 Systematic positionAccording to the characters of anatomy, foral organogenesis et. of Euptelea pleiospermum, we considered that Eupteleaceae might occupy the basic position in the Ranunculales, and might be a primary taxon in woody dicotyledons.