Yes, if the citrus plant is grafted the stock plant can sprout from below the graft, resulting in two different citrus species on the same plant
Limb or Tree Limb Arm or division
limb
Extremity.
Limb
a limb
Limb
limb, bough, scion
What you are talking about is grafting. This can be done (and is done commercially), between closely related plants (normally at a genus or species level). The success of the graft is determined by the type of plant. It is commonly done with fruit trees and rose plants, where the best characteristics of the fruit (or flower bearing) plant are added to the rootstock of another (related plant), which has a good, vigorous root system. Natural grafts sometimes occur in nature, but normally on the same plant - this happens where two branches rub together in the wind, over time they fuse and form a permanent attachment.
Branch is one and bough is another.
Arm. Leg.
It is proximal as the knee is closer to the median / midline of the body than the foot. The foot is distal. Distal suggests a structure being further away from the median plane or the root of the limb than another structure in the limb. Proximal refers to a structure being closer to the median plane or root of the limb than another structure in the limb
A prosthetic leg, or prosthetic limb