leek
韮 refers specifically to the leek plant, a vegetable with long flat leaves. There are no extended abstract meanings.
韮 combines the grass radical 艹 with 韭, which itself depicts a type of allium plant. The character likely originated as a way to specify the leek among similar plants.
The grass radical 艹 sits above 韭, a shape that resembles a bundle of long leaves growing from the ground. Together they make the leek plant.
For キュウ, imagine a leek shaped like the letter Q: Q -> キュウ, and the leek's curved stalk reminds you of the reading.
garlic chives (Allium tuberosum); Chinese chives; Chinese leek
Chinese onion (Allium chinense); Chinese scallion; Kiangsi scallion; rakkyo
stir-fry of pork liver and garlic chives
Chinese chive; garlic chive (Allium tuberosum)
Japanese onion (Allium thunbergii)
Japanese quillwort (Isoetes japonica)
Microtis unifolia (species of orchid)
broadleaf wild leek (Allium ampeloprasum)