Flowering, seeding, and seedling establishment of narrow-leaved Snow Tussock,Chionochloa Rigida

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Abstract
The infrequent flowering years of the narrow-leaved snow tussock appear to depend on abnormally high temperatures during the long-day period of summer in the season before flowering. Physiological induction then occurs and morphological initiation of the inflorescence may take place during autumn, or it may be delayed until early spring, i.e., for about eight months. IntenSity of flowering increases with the duration of high temperatures during the inductive period when daylength exceeds about 14 hnurs. Even so, considerable variation in the intensity of flowering occurred both between sites and between individual tussocks at a site. In their flowering response the plants appear to be insensitive to differences in light intensity. Inflorescence development resembles that already described for the genus. It is increasingly delayed at higher altitudes, but is not subject to control by daylength. Floret size and seed weight decrease significantly with altitude. Seed set and viability are usually satisfactory at sites below 1,300 m, but above 1,000 m seed set is variable and usually small, and moreover, viability is low. Some germination and establishment occur at most sites studied, but viable seeds may remain dormant on the ground for several years. However, fire may lead to immediate germination and establishment of many seedlings. Because of the longevity of individual tussocks the number of seedlings needed to maintain the status quo is relatively small. There is little indication that narrow-leaved snow tussock is a relic species in the areas studied.

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