Bot. [f. Gr. καλύπτρα covering + -GEN taken in sense of ‘producer.’] The outer zone or layer of the meristem or primary tissue of the youngest part of plants.
1881. Nature, XXIII. 288. Four zones of meristem:—calyptrogen, dermatogen, periblem and plerome.
1884. Bower & Scott, De Bary’s Phaner. & Ferns, 9. Since this accession originates in certain cases from a special layer of meristem, the latter is to be distinguished as the calyptrogen.
