LIFESPAN AND BUDDING POTENTIAL OF LEMNA AS A FUNCTION OF AGE OF THE PARENT– A GENEALOGIC STUDY

S ummary Experiments tested claims that, in Lemna , increasing age of the parent reduces lifespan and reproductivity of the offspring. Successive cultures of n th buds (‘n th ‐bud lines’, n = 1–10), and also of late‐buds and last‐buds, were observed for size and number of the buds they produced, and lifespan. Advancing age of the parent frond affected bud size, but had little or no effect on either lifespan or budding capacity of the offspring. First, second, and third buds of all lines were larger than their parents; successive buds then decreased in size approximately linearly with bud number or time of separation. Small, late buds, as parents, have smaller buds than do their early siblings. Numbers of buds produced by late buds, as parents, differ little from the numbers produced by their earlier siblings. Both groups vary randomly; together, their productivity is well represented by a normal distribution curve. Lifespans of early and late buds do not, on the average, differ markedly. ‘Survival curves’ indicate that early buds are more likely to survive into middle age (to produce nine‐ten buds), but late buds are more likely to survive into very old age and to produce thirteen‐fifteen buds. Bud production by late offspring is somewhat slower than that by early offspring.