LEAF APPEARANCE AND SENESCENCE PATTERNS OF SOME PASTURE SPECIES

Five pasture species, very different in their morphological organizati on (four dicotyledons: Plantago lanceolata, Sanguisorba minor, Ranuncu lus repens, Taraxacum officinalis and one grass: Dactylis glomerata), were grown as spaced plants in pots, thus excluding competition for li ght, to study the proportion of senescent leaves. In May, after a 6 mo nth period, the proportion of partially or totally senescent leaves va ried from 20% to 80%. Four plant characteristics were important: leaf appearance and senescence rates, leaf lifespan and date and type of do wering. Plantago lanceolata had the longest lived foliage and the smal lest proportion of senescent leaves. In contrast, Taraxacum officinali s had the most rapid leaf turnover and Dactylis glomerata had the slow est rate of leaf appearance. Sanguisorba minor and Ranunculus repens w ere almost identical, with intermediate leaf characteristics in all re spects. These results illustrate the fact that the four characteristic s studied, and not simply the species' phenology, must be taken into a ccount in order to compare growth between species. The likelihood of t hese characteristics remaining the same when species are in dense swar d is considered.