bamboo, the handle of the spear
籚 centers on bamboo, specifically a bamboo spear handle. The meanings are closely linked: bamboo as the material and its use in making a spear shaft.
籚 combines 竹 (bamboo) with 盧, which likely contributes the sound. The character originally referred to a bamboo spear handle.
The top 竹 is bamboo, and the bottom 盧 looks like a sturdy container. Imagine a bamboo shaft fitted into a spearhead: 籚 is the bamboo handle of a spear.
For ロ, picture a row of bamboo spears lined up: row -> ロ, and each spear has a bamboo handle.