This study describes the early development of the Arabidopsis thaliana flower from initiation to opening. Using scanning electron microscopy, the researchers divided the process into 12 stages based on landmark events. Stage 1 begins with the initiation of a floral buttress on the apical meristem. Stage 2 starts when the flower primordium separates from the meristem. Sepal primordia appear in stage 3 and grow to overlie the primordium in stage 4. Petal and stamen primordia appear in stage 5 and are enclosed by the sepals in stage 6. During stage 6, petal primordia grow slowly, while stamen primordia enlarge more rapidly. Stage 7 begins when the medial stamens become stalked, followed by the development of locules in stage 8. Stage 9 is a long stage where all organs lengthen rapidly, including the gynoecium. Stage 10 begins when petals reach the length of the lateral stamens. Stigmatic papillae appear in stage 11, and petals reach the height of the medial stamens in stage 12. This final stage ends when the 1-millimeter-long bud opens. The study also describes the structure and development of the Arabidopsis flower, including the formation of sepals, petals, stamens, and the gynoecium. The researchers found that the development of floral organs is controlled by genes, and that mutations in these genes can lead to abnormal development. The study provides a detailed timeline of flower development, which is important for understanding the genetic mechanisms that control flower development in Arabidopsis. The study also highlights the importance of scanning electron microscopy in visualizing the development of floral organs. The researchers observed that the apical meristem changes from slightly convex to distinctly dome-shaped during the transition from vegetative to floral growth. The study also discusses the direction of inflorescence spiral and the origin of flowers. The researchers found that the direction of flower production on any one main apex is apparently decided at random and is maintained unchanged. The study concludes that the 12 stages defined in this study will be useful in interpreting the action of genes that control this process. The study also provides information on the surface morphology of mature and developing floral organs, including the presence of stomata, epidermal cells, and other structures. The study also discusses the development of nectaries and their presence in mature flowers. The researchers found that nectaries arise late in flower development and may be limited by available space and nutrients. The study also discusses the development of stipules in Arabidopsis and their presence on young cauline leaves. The researchers found that stipules are present on the base of young cauline leaves in Arabidopsis. The study also discusses the development of the apical meristem and the formation of flower primordia. TheThis study describes the early development of the Arabidopsis thaliana flower from initiation to opening. Using scanning electron microscopy, the researchers divided the process into 12 stages based on landmark events. Stage 1 begins with the initiation of a floral buttress on the apical meristem. Stage 2 starts when the flower primordium separates from the meristem. Sepal primordia appear in stage 3 and grow to overlie the primordium in stage 4. Petal and stamen primordia appear in stage 5 and are enclosed by the sepals in stage 6. During stage 6, petal primordia grow slowly, while stamen primordia enlarge more rapidly. Stage 7 begins when the medial stamens become stalked, followed by the development of locules in stage 8. Stage 9 is a long stage where all organs lengthen rapidly, including the gynoecium. Stage 10 begins when petals reach the length of the lateral stamens. Stigmatic papillae appear in stage 11, and petals reach the height of the medial stamens in stage 12. This final stage ends when the 1-millimeter-long bud opens. The study also describes the structure and development of the Arabidopsis flower, including the formation of sepals, petals, stamens, and the gynoecium. The researchers found that the development of floral organs is controlled by genes, and that mutations in these genes can lead to abnormal development. The study provides a detailed timeline of flower development, which is important for understanding the genetic mechanisms that control flower development in Arabidopsis. The study also highlights the importance of scanning electron microscopy in visualizing the development of floral organs. The researchers observed that the apical meristem changes from slightly convex to distinctly dome-shaped during the transition from vegetative to floral growth. The study also discusses the direction of inflorescence spiral and the origin of flowers. The researchers found that the direction of flower production on any one main apex is apparently decided at random and is maintained unchanged. The study concludes that the 12 stages defined in this study will be useful in interpreting the action of genes that control this process. The study also provides information on the surface morphology of mature and developing floral organs, including the presence of stomata, epidermal cells, and other structures. The study also discusses the development of nectaries and their presence in mature flowers. The researchers found that nectaries arise late in flower development and may be limited by available space and nutrients. The study also discusses the development of stipules in Arabidopsis and their presence on young cauline leaves. The researchers found that stipules are present on the base of young cauline leaves in Arabidopsis. The study also discusses the development of the apical meristem and the formation of flower primordia. The