Remarks

Visual assessment (Pls. I and II) and graphic analysis (Fig. 6) demonstrates a changing pattern for growth of the erect stem during the year. The highest percentage of terminal buds, branches and gonangia occur in the autumn to winter season. All these stem characters are found with decreasing frequency on the stem as water temperatures rise in spring and summer. Branches rarely occur on stems when water temperatures approach the maximum. Gonangia in contrast rise in numbers with the approach of maximum temperature. All in all, these trends suggest a strong correlation between temperature and the seasonal form and maturity attained by the stem. However, when this correlation is tested utilizing the method of least squares, the assumption that temperature is the controlling factor in seasonal habit is less obvious. The percentage of variability explained ranges from non-significant for the feeding polyps (0.4%) to varying degrees of significance, for the other structures.

For the branches and terminal buds it is 27%.

For the gonangia it is nearly twice as high, namely 46%.

In brief, the analysis of the long-term series indicates that changes in stem form occur throughout the year. These are related to the four seasons and thus indirectly to temperature. The degree of correlation between temperature varies for the stem characters assessed. It is lowest and non-significant for the feeding polyps. It is highest and quite significant for the gonangia. Correlation for the terminal buds and branches is significant and in between the two extremes.