A num­bers gAme

Landscape (UK) - - In The Home -

Na­ture has de­vised two dif­fer­ent strate­gies for seed pro­duc­tion. Some plants re­lease count­less num­bers of very small seeds and oth­ers a smaller num­ber of larger seeds. The for­mer rely on strength in num­bers and the odds that at least some will sur­vive to adult­hood. The lat­ter in­vest a lot of en­ergy-pro­duc­ing seeds with a gen­er­ous food re­serve, in the hope it will boost the prospects of each seedling. At more than 1ft (30cm) long and weigh­ing up­wards of 3st (18kg), the world’s largest seed is the coco de mer, or sea co­conut, pro­duced by the lodoicea palm. Av­o­ca­dos and peaches also have very big seeds. At the other end of the scale are seeds so tiny they look like dust. Orchid seeds are the small­est of any plant, those of the del­i­cate lady’s tresses orchid weigh­ing just 2 mi­cro­grams. Ev­ery few years, some wood­land trees, notably the oak and beech, re­lease huge num­bers of seeds. Known as mast years, they oc­cur in an ir­reg­u­lar cy­cle, but are usu­ally be­tween two and five years apart. All the trees in a pop­u­la­tion syn­chro­nise to mass-pro­duce seeds at the same time, up­wards of 50,000 acorns fall­ing from a sin­gle oak. Al­though there is no con­sen­sus on how or why this hap­pens, many be­lieve the trees are adopt­ing an ‘all or noth­ing’ ap­proach. All their en­ergy is put into pro­duc­ing so many seeds that preda­tors can­not pos­si­bly eat them all. This en­sures the sur­vival of such a high num­ber that re­sources can be chan­nelled into other ac­tiv­i­ties, such as trunk growth, in the in­ter­ven­ing years. This strat­egy works well for the trees, but how they co­op­er­ate to achieve it re­mains a mys­tery.

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