 SHORTROOT(SHR), and microRNA165/166 also participate in that process, while Callose Synthase 3(CALS3), inhibits the locations where SHORTROOT(SHR), and microRNA165 can go.In the embryo, root phloem develops independently in the upper hypocotyl, which lies between the embryonic root, and the cotyledon.In an adult, the phloem originates, and grows outwards from, meristematic cells in the vascular cambium.