One of the most prolific is canna, which is Latin for reed, tube, or pipe. Turns out you can get a LOT of mileage from that meaning:

Cane: Referring to the plant, walking stick, or slender rod.

Canal: An artificial waterway, from the Latin canalis (pipe/groove).

Channel: A conduit or passage.

Cannon: From Italian cannone, meaning "large tube".

Canon: A rule or standard (originally from a reed used as a measuring stick).

Cannibal: Historically connected to this root through a complex path involving "Carib".

Cannister / Canister: A container, often cylindrical.

Cannula: A small tube for insertion into the body.

Canyon: Derived via Spanish cañón (tube/pipe).