根 root

This is a weird tree because the CONES are not on the branches but instead they grow from the roots.

It's good for trees to have a root. Stability and nutrients from the soil. You know the deal.

the fundamentals ★★★☆☆
根 (root) + 本 (book / the real) = 根本 (the fundamentals)

the fundamentals (how is it different from 基本？ Well, with 根本, the emphasis is: the fundamental, deep, organizing principles, not the most easy 'for dummies' bits). The essential and underlying - as opposed to on the surface and easily apparent) Also handy:こんぽんてきな (the adjective form)

roof ★★☆☆☆ KUN ON
屋 (store) + 根 (root) = 屋根 (roof)

roof . That's right, not root. Roof!

patience ★★☆☆☆
根 (root) + 気 (mood) = 根気 (patience)

patience. You need 根気 to be able to 我慢 (がまん）。
Often used like 根気がいい（she's very patient!) or, 根気よくｘｘｘした！　(you did xxx very patiently!)

balls ★★☆☆☆
根 (root) + 性 (sex / essential nature) = 根性 (balls)

guts　/balls (for instance, giving yourself cigarette burns to prove some kind of point about being a man)