Figure 1.

Life history of an Arabidopsis plant. The seed was photographed prior to surface sterilization and placement on plant nutrient medium (Haughn and Somerville 1986) solidified with 0.6% (w/v) agar. The plate was sealed against contaminants using surgical tape and incubated vertically at 22° under continuous light. The radicle (embryonic root) had emerged from the testa (seed coat) by 3 days. Green cotyledons (embryonic leaves), emerging true leaves, an expanded hypocotyl (embryonic stem), and an elongated root were apparent by 7 days. After 13 days, the seedling was transferred to soil and grown at room temperature under continuous fluorescent light, then photographed shortly after the transition to flowering (28 days) and after dry seed pods (siliques; arrowhead) containing mature seeds were apparent (50 days).