TITLE	Altitudinal variation of resin ducts in Pinus taiwanensis Hayata (Pinaceae) needles
AUTHOR	Chiou-Rong Sheue Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan Yuen-Po Yang Department of Biological Sciences, National Sun Yat-sen University, Kaohsiung 804, Taiwan Ling-Long Kuo-Huang Department of Life Science, National Taiwan University, Taipei 106, Taiwan
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ABSTRACT	The variation of resin ducts in needles of Pinus taiwanensis along an altitude gradient (700 m- 3,100 m) in central Taiwan is revealed for the first time in this study, including position type, number, size, arrangement pattern and anatomical structural variation. Three types of resin ducts-medial, external and septal-were found according to their relative positions in the mesophyll. All needles sampled showed combinations of these three resin duct types. Mostly, 3-7 resin ducts were found in the mesophyll per needle, and the number of resin ducts was significantly greater at mid altitudes than at high and low altitudes. Septal ducts decreased in number with an increase in altitude; however, needles from mid altitudes had more external ducts. Eight patterns (basic and patterns I-VII) of resin ducts in the mesophyll of needles were delineated to present the arrangement variations. In addition to the primary ducts found in the mesophyll, we found the rare bundle sheath ducts in some needles, and their frequencies decreased obviously with an increase in altitude. The consistent combination feature of medial, external, and septal ducts in needles of P. taiwanensis from Taiwan could be easily distinguished from those with medial ducts from mainland China. However, this difference has unrecognized before, and it should be considered in future taxonomic work.
KEYWORD	Altitudinal variation; Needle; Resin duct; Pinus taiwanensis;
ARTICLE INFO	Botanical Bulletin of Academia Sinica, Volume 44 Number 4 October 2003, page 305-313, 9 pages
PUBLISHER	Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan, Republic of China