Growth and Translocation in a Clonal Southern Hemisphere Sedge, Uncinia Meridensis

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Abstract
(1) Uncinia meridensis is a Southern Hemisphere sedge showing a clonal growth habit. Leaf development and dry weight accumulation in each tiller show periodicity and this has enabled the construction of an age-based life cycle for the tillers. (2) Individual tillers may live for 6 years and their rhizomes may persist after the death of the above-ground tissues. The rate of leaf production on a tiller decreases from eight per year in year 0 to three per year in year 5. Individual leaves persist for more than 1 year and the longest leaves are produced in year 3. (3) Flowering becomes possible during year 2 but flowering structures are a small part of the total dry weight of a flowering tiller. A mean of about ten seeds per inflorescence is produced in all age classes of flowering tiller, but the probability of seeds germinating to form year 0 tillers within the study area was zero. In contrast, vegetatively produced tillers had a high probability of surviving: 0.56 in year 0 and 0.94 in year 1. (4) Young vegetative offspring without leaves and roots are totally parasitic on older tillers; they receive 14C labelled photoassimilate from parent vegetative tillers and from photosynthetic inflorescences (which export 52% of their photoassimilate) on flowering tillers of older tiller generations. (5) The success of vegetative reproduction appears to result from the physiological interdependence of tillers within a clone where patterns of reciprocal translocation are evident between older tillers bearing leaves. The flowering tiller exports 10% of its carbon to its vegetative offspring while the offspring export 2% of their carbon to the parent flowering tiller. Translocation also occurs between tillers connected indirectly by older leafless tillers. (6) It is suggested that the vegetative reproduction, clonal growth and conservation of energy and nutrients exemplified by U. meridensis should be particularly important in the adverse tundra environment where clonal perennial plants predominate.

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