thicket, bush, underbrush, grove
籔 centers on dense, tangled vegetation: a thicket, bush, underbrush, or small grove of closely growing plants.
籔 combines 竹 (bamboo) with 數, which likely contributes the sound and may relate to counting or density, suggesting a dense stand of bamboo or vegetation.
Bamboo 竹 grows thickly above a dense, tangled base 數, like a grove so crowded it's hard to count the stalks.
For ソウ, imagine a dense thicket so thick you have to sew your way through: sew -> ソウ, pushing through the bamboo grove.