turnip
蕪 centers on the turnip plant, a root vegetable with edible leaves. The meaning is specific to this plant.
蕪 combines the plant radical 艹 with 無, which likely provides the sound. The character specifically refers to the turnip plant.
The grass radical 艹 sits above 無, like a turnip's leafy greens growing above the root. Think of the whole plant: leaves on top, turnip below.
For ブ, imagine a turnip growing so big it makes a booming sound when it pops out of the ground: boom -> ブ. The turnip's leafy top rustles as it emerges.
turnip (Brassica rapa)
rutabaga (Brassica napobrassica); Swedish turnip; swede
thick wakame leaves from near the stem
wild land; wasteland; wilderness
turnip miso soup
turnip (Brassica rapa)
steamed fish with grated turnip on top
coarse speech or writing; humble reference to one's own words
disordered; confused; unpolished; rough
narezushi of amberjack and turnip (Kanazawa speciality)