By reduplication from zalal; tremulous, i.e. A twig -- sprig.
see HEBREW zalal
H2150. zalzal
[זַלְזַל] noun [masculine] (quivering) tendrils; — only plural tendrils of vine הַזַּלְזַלִּים Isaiah 18:5 ("" הַנְּטִישׁוֺת), in figure of Yahweh's destroying the Assyrians.