Three Korean lawn grasses, Zoysia japonica Steud., Z. matrella (L.) Merr., and Z. tenuifolia Willd., have erect stems, and each stem has many leaf-nodes at its base. Assignment was made from I to VIII to indicate the developmental stages of leaf-nodes by their numbers in each stem. In a given rhizome, the erect stems being formed at compound node were in a decreasing order of leaf-node stages as the rhizome continued to grow. While younger stems kept growing and increased their leaf-node numbers, the older one which already had attained sufficient number of leaf-nodes flowered, and died after seed setting.
The minimum number of leaf-nodes required to flower was 12 in Z. japonica and Z. matrella, and 18 in Z. tenuifolia. It is concluded that a certain number of leaf-nodes is required for zoysia grasses to flower.
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