flower, petal
葩 centers on the delicate, colorful part of a plant: a flower or its petals. It refers to blossoms in full bloom, emphasizing their beauty and fragility.
葩 combines 艹 (grass/plant) with 皅, which likely contributes the sound and relates to white or bright, suggesting a bright flower. The exact historical development is uncertain.
The grass radical 艹 sits above 皅, which looks like a white blossom opening. Picture a white flower blooming among the grass: 葩 is a flower or petal.
For ハ, imagine a flower laughing 'ha!' as it opens its petals: ha -> ハ, and the flower shows its beauty.