Left tree radical - pictograph of a tree, the indexing radical for arboreal characters. In 棕 it marks the palm tree, whose fibrous brown trunk gives Chinese its everyday word for the colour brown. Same family of named trees: 桃 peach, 松 pine, 柏 cypress, 桐 paulownia.
Right 宗 supplies the sound zōng exactly. 宗 pictures an ancestral tablet under a roof - the family shrine - but the ancestor meaning is not carried into 棕. The same phonetic kernel runs through 综 to combine, 踪 trace, 鬃 mane - all zōng-readings.
