Most of the angiospermic plants are oviparous.Because their embryo grows only after the seed is sown in the soil.
That means when the seed is separated from parent body , and sown in the soil, it grows in to baby plant .
That is why the angiospermic plants are oviparous.
But there are some plants like Mangrooves in which the seeds germinate when they are still in the ovary of the plant.
Such plants are called viviparous plants.