In seeds of black pepper (Piper nigrum) and beet (Beta vulgaris), a portion of the maternal nucellus persists as a nutritive tissue surrounding the embryo. What is this persistent nucellar layer called?
Answer and explanation
Correct answer: B. Perisperm
- Step 1: In most angiosperm ovules, the maternal nucellar tissue is completely digested during embryo sac expansion and endosperm formation.
- Step 2: In some families (such as Piperaceae and Chenopodiaceae), a thin, residual layer of diploid nucellus persists in the mature seed.
- Step 3: This persistent remnant of the nucellus is designated as perisperm (e.g., black pepper, beet, coffee, cardamon).
Answer
Perisperm
Why not the others: 'Pericarp' is the wall of the fruit developed from the ovary wall; 'Endosperm' is the triploid nutritive tissue formed by triple fusion; 'Caruncle' is a fleshy, lipid-rich outgrowth of the outer integument around the micropyle seen in castor seeds.
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