Comparative Study of Catheter Secondary Xylem Ducts of FourSpecies of Oleaceae Plants ——Ligustrum quihoui, Ligustrum lucidum, Jasminum nudiflorum, Osmanthus fragrans

By use of vessel element segregation technology, Ligustrum quihoui, Ligustrum lucidum, Jasminum nudiflorum, Osmanthus fragrans duct type and quantity of secondary xylem, vessel element length, diameter, perforation plate type and the tail characteristic are all studied. The results showed that: Perforation plates of the four kinds of plants are simple perforation plate. The secondary wall is a hole pattern thickening, but also obviously whorled threaded tertiary thickening. The duct type falls into three: two tailed ends, one tailed end, and two tailless ends. The vessel length, diameter, length of tail end and wall inclination angle are all found to have differences. The four plant species are highly evolved plants, and the evolution of the molecular characteristics of the same plant is not synchronous at the same rate. The individual development of the secondary xylem ducts of the four plants repeats the course of the system development.