The ripened and otherwise modified wall of a plant ovary(noun)
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Use "seed vessel" in a sentence
"* Franklinia Alatahama. but the flowers are larger, and more fragrant than those of the Gordonia Lascanthus, and are sessile; the seed vessel is also very different."
"This column was crowned with the appearance of a shining octagonal church, which grew forth from the stem like the calyx of a flower or the seed vessel of a poppy."