Altitudinal Variation Of Needle Structure In Pinus Taiwanensis Hayata (Pinaceae) From Mount Huangshan

The shapes of the needles, as well as the numbers, position types, arrangement patterns, sizes of their included resin ducts, are described in the present paper, together with their variations along the altitude gradient. The material was collected from Mount Huangshan at the height of 300 - 1,800 m and the results had been compared to that of the P. taiwanensis from taiwan and other common members in Pinaceae in China.Four types of resin ducts are recorded in this study, including three primary patterns (external, medial, endonal) and one secondary pattern (bundle sheath resin duct). Several points are revealed as follows. (1) The lengths of the needles in P. taiwanensis from Mount Huangshan, which range from 3 cm to 16 cm, are gradually diminished as the altitude increase. (2) The numbers of different types of resin ducts or combinations change along the altitude gradient with exception of the combination of the external and medial, while the total number in each needle is about 3 to 8. (3) Only one kind or several kinds of resin ducts with different arrangements are present in the needles. The numbers of external resin ducts from different heights are significantly different and they can not be found above 1100 m; on the contrary, the needles bear more medial resin ducts when they situate in a higher elevation, and these are in agreements with the endonal above the height of the 1100 m; most of the boundle sheath resin ducts are found in the needles at low and mid elevation. (4) The areas of the basic patterns are much larger than others within the primary pattern. As to the bundle sheath resin duct of the secondary patterns, they are the smallest in the size. The total areas of the resin ducts in the needles vary from one altitude to...