The banana plant is called a 'banana tree' in popular use, but it's technically regarded as a herbaceous plant (or 'herb'), not a tree, because the stem does not contain true woody tissue.
The protons and neutrons cluster together in the central part of the atom, called the nucleus, and the electrons 'orbit' the nucleus. A particular atom will have the same number of protons and electrons and most atoms have at least as many neutrons as protons. Protons and neutrons are both composed of other particles called quarks and gluons. Protons contain two 'up' quarks and one 'down' quark while neutrons contain one 'up' quark and two 'down' quarks. The gluons are responsible for binding the quarks to one another.
The nucleus of an atom contains neutrons and protons. Almost all of the mass in an atom is made up from the protons and neutrons in the nucleus. Because the nucleus is only made up of protons and neutrons, it is positively charged.