Tercine

Tercine, the conical papilla upon the placenta of spermaphytic plants which forms the earliest stage of the ovule (q.v.) - also called the nucellus or, more objectionably, the nucleus. Its base becomes elongated into the funicle, and in most cases it is enclosed in succession by the secundine and primine which grow up round it like cups springing from its base (chalaza). From one of its hypodermal ce11s the embryo-sac (megaspore) originates; and in the ripe seed some of its tissues may survive unabsorbed, as the nutritive perisperm (q.v.).