The "wear" and "write" definitions of are in fact different words (and we don't use the kanji for "wear" anymore). Moreover, as you said, the true old form has the Bamboo radical on the head, in other words, is today's . The kanji is made of and , where indicates the pronunciation. Thus this kanji once became a carpool of several similar-sounding words.
: "to write, to author, written, evident" → ****
* {LH}[]{HL} (OC _*m-trak_): "put on, turn on, get on" → ****
Note that the distinction of and is tradition in Japan and PRC. Taiwan only recognizes as the proper form for both.
was originally handwriting variant of . The top part was a common variation of (; radical Grass on the top) now becomes non-standard.
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