The primary meristems in turn produce the two secondary meristem types. Plants produce both leaf and flower primordia cells at the shoot apical meristem (SAM). The shoot apical meristem is between the cotyledons. Unlike the shoot apical meristem, the root apical meristem produces cells in two dimensions. The "apical embryo domain", gives rise to the shoot apical meristem and cotyledons. More simply stated, lateral bud formation is inhibited by the shoot apical meristem (SAM). Such new plants can be grown from shoot cuttings that contain an apical meristem. The cauliflower head is composed of a white inflorescence meristem. A primordium, the nascent leaf, forms at the least crowded part of the shoot meristem. The function of "WUS" in the shoot apical meristem is linked to the phytohormone cytokinin. The center of the stem, which contains the growing point (the apical meristem), is sunken. The leaves have reticulated venation and lack a basal meristem. The two foliage leaves grow continuously from a basal meristem reaching lengths up to . Early embryogeny includes all stages after suspensor elongation but before root meristem development. Branch roots arise from this primary meristem tissue.