Wood radical 木 + 句 (gōu/jù) phonetic. 枸 has three readings: gǒu (枸杞 goji, 枸骨 holly), by far the most common, jǔ (枸橼 citron), and gōu (a rare "bent" reading). For practical purposes, when you see 枸 today it's almost always pronounced gǒu in 枸杞.
Tree radical on the left marks 枸 as a plant, used almost exclusively in compound names like 枸杞 (goji berry / wolfberry) and 枸骨 (Chinese holly). The radical groups it with the rest of the plant kingdom in script: 桃, 李, 梨, 桔.
Right side supplies the sound: jù → gǒu / jǔ / gōu (the character carries multiple readings depending on which plant it names). 句 is purely phonetic; its 'sentence' meaning is not active. Same phonetic family as 驹 colt, 拘 detain, 狗 dog, sharing a bound, hooked, or curled sense.
