/ Dictionary / Index C calyptrogen: Meaning and Definition of Find definitions for: ca•lyp•tro•gen Pronunciation: (ku-lip'tru-jun), [key] — n. Bot. the histogen layer that develops into the root cap. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. calyptra calyx Related Content Daily Word Quiz: perspicacious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language