A rosette by any other name

Leaves emerge from the apical meristem in a reproducible pattern in plants. In Arabidopsis plants, the pattern of leaf growth varies with developmental age. In young seedlings, the first (cotyledons) and the second set (primary leaves) of leaves emerge opposite to each other. Subsequent leaves emerge in a pattern that results in a spiral arrangement. This change in leaf arrangement is often considered to mark the transition from juvenile to mature growth stages.

Arabidopsis rosette growth

The time-lapse movie shows the development of a rosette over a period of 14 days, starting from about a week after germination. The seedlings were grown in continuous light. The time interval between images in the movie is 30 min.

Time course of leaf area increase.

The graph above shows the time-course of the increase in leaf area of rosette growth from a time-lapse series like the one shown on this page. The data were obtained from images captured every hour and are the average from several plants. After about 12 days, it appears that growth starts to decrease but the apparent decrease is the result of leaves overlapping each other as the leaves expanded so that they were no longer detected by the technique used to measure the leaf area.