The Comparative Biology of Closely Related Species: VI. ANALYSIS OF THE GROWTH OF TRIFOLIUM REPENS AND T. FRAGIFERUM IN PURE AND MIXED POPULATIONS

An analysis was made of the first season's growth of pure andmixed stands of Trifolium repens and T. fragiferum. T. repens,although having smaller seeds and cotyledon area, achieved afaster early rate of leaf production than T. fragiferum andquickly developed a larger area of leaf both in pure standsand in mixtures. By the 18th and 21st weeks from sowing, T.fragiferum had more elongated petioles than T. repens, leaveswere borne higher in the canopy and contributed an increasingpart to the Leaf Area Index of mixtures. The increase in leaf area of swards with time was largely associatedwith increased area of individual leaves. The differences betweenspecies were largely due to differences in number of leaves. These results are discussed in relation to the conditions underwhich stable associations of species may be formed.