Cengage Horticulture Exam 1 Practice

The key idea is that a successful graft forms a continuous vascular connection between the scion and rootstock. When the cambial layers—the growth meristems just beneath the bark—are aligned, undifferentiated cells at the interface proliferate to create a bridge of callus tissue. Over time this callus differentiates into xylem and phloem, tying the two parts into one plant so water, minerals, and sugars can move freely between them. That cambial alignment with a callus bridge is the concrete signal that the graft union is establishing a functional bond. Other signs like leaves changing color, or the graft becoming completely independent immediately, or no growth at the graft site, do not indicate a successful union. Leaf color changes are more likely stress or nutrient issues; immediate independence means the connection never formed; and no growth at the graft site suggests failure to SAMPLEheal.