| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 1998: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1997: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Research Abstract |
The structural diversity of inflorescences, flowers and pods were investigated in the tribe Desmodieae of Leguminosae, and then the relationships among structures and their phylogenetic implications were assumed.
1. Inflorescence structure
The structural relationships between racemose and pseudoracemose inflorescences were examined. In genus Dendrolobium with racemose inflorescences, flowers are arranged in all direction of the inflorescence axis in spiral, only in the abaxial side of the axis, or first in the abaxial direction and then in spiral. On the other hand, in other genera with pseudoracemose inflorescences flowers in the partial inflorescence subtended by the bract borne on the inflorescence axis represent the arrangement restricted in the abaxial side of the partial inflorescence axis or the intermediate pattern of arrangement. Thus, the partial inflorescences of the pseudoracemes are assumed to correspond to the racemes. By reduction in size and form of the subtending leaves
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into the simple bract the distal part of shoot surrounded by racemes may be transformed into the pseudoraceme.
2. Flower structure
Two types of flowers in tribe Desmodieae, that is, simple and explosive types, were examined morphologically, anatomically and morphogenetically. The explosive type was observed in genera of Alysicarpus, Christia, Codariocalyx, Desmodium except D.caudatum, Pycnospora and Uraria, while the simple type was observed in Aphyllodium, Campylotropis, Dendrolobium, Desmodium (only D.caudatum), Kummerowia, Lespedeza, Phyllodium and Tadehagi. Morphological and anatomical observations revealed that wings are tightly fused with keel-petals via a protuberance of tissues on the outside of the keel-petal in the explosive type, and that the length from the fused point to the base of petal is longer in keel-petals than wings in explosive type. These features are closely related with the explosion of petals. In comparison with a molecular phylogenetic tree the explosive type of flower was considered to be evolved from the simple type of flower involving the loss of floral nectary
The flower structure was shown to be important as a taxonomic character in Dendrolobium. Using the flower structure the delimitation of known species becomes clear and a new species was distinguished from them in New Guinea (Ohashi, Ye and Nemoto, in press).
3. Pods structure
The structural diversity of pods were examined on 68 species representative of three subtribe and 25 genera in tribe Desmodieae. There were noteworthy variations in the position, thickness and distribution pattern of sclerenchyma layer in the pericarp, and five types of pericarp structures and five types of joint structures were distinguished. On the basis of these types evolutionary trends of pericarp and joint structures were assumed, and the genus Alysicarpus has the most characteristic pericarp structure and was regarded as having the most advanced pod. Less
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