(b) Dust seed are very small dry and light, e.g.,$ 0.0001 mg $ in Orchis.

Flattening help the fruits to remain afloat in air, e.g., Dalbergia, Albizzia.

Balloon fruits are inflated, e.g., Cardiospermum, Colutea $(balloon\,\, by\,\, persistent\,\, calyx)$.