The bodies of seed plants are comprised of two classes of organs with contrasting growth and symmetry attributes. Stems and roots are indeterminate organs that exhibit apical growth at apical meristems and radial growth at the vascular cambium, a pattern of growth that results in primarily radially symmetric organs. Lateral organs of the shoot, for example cotyledons, leaves, and floral organs,...

The bodies of seed plants are comprised of two classes of organs with contrasting growth and symmetry attributes. Stems and roots are indeterminate organs that exhibit apical growth at apical meristems and radial growth at the vascular cambium, a pattern of growth that results in primarily radially symmetric organs. Lateral organs of the shoot, for example cotyledons, leaves, and floral organs,...

The higher-plant shoot meristem is a dynamic structure whose maintenance depends on the coordination of two antagonistic processes, organ initiation and self-renewal of the stem cell population. In Arabidopsis shoot and floral meristems, the WUSCHEL (WUS) gene is required for stem cell identity, whereas the CLAVATA1, 2, and 3 (CLV) genes promote organ initiation. Our analysis of the interaction...

The shoot apical meristem (SAM) is a small population of stem cells that continuously generates organs and tissues. This review covers our current understanding of organ initiation by the SAM in Arabidopsis thaliana. Meristem function and maintenance involves two major hormones, cytokinins and auxins. Cytokinins appear to play a major role in meristem maintenance and in controlling meristematic...

Inflorescence morphology is incredibly diverse. This diversity of form has been a fruitful source of inquiry for plant morphologists for more than a century. Work in the grasses (Poaceae), the tomato family (Solanaceae), and Arabidopsis thaliana (Brassicaceae) has led to a richer understanding of the molecular genetics underlying this diversity. The character of individual meristems, a combinat...

The aerial parts of Arabidopsis are ultimately derived from the primary shoot apical meristem which is established during embryogenesis (Sussex, 1989; Evans and Barton, 1997). Over the plant life cycle, a series of growth phases reflect the activity of this meristem (Poethig, 1990; Schultz and Haughn, 1993; Ratcliffe et al., 1998). Following germination, the shoot apical meristem generates leaf...

BACKGROUND The shoot apical meristem (SAM) is an indeterminate structure that gives rise to the aerial parts of higher plants. Leaves arise from the differentiation of cells at the flanks of the SAM. Current evidence suggests that the precise regulation of KNOTTED1-like homeobox (KNOX) transcription factors is central to the acquisition of leaf versus meristem identity in a wide spectrum of pla...