The stem of the Jerusalem Artichoke, a typical short day plant, exhibits an intense vegetative growth during summer and early autumn. Flowerbuds in this country do not initiate before the end of September. During the vegetative period the more robust stems show at their apical end living medullar parenchyma over a length of five to ten inches.

Acta botanica neerlandica

CC BY 3.0 NL ("Naamsvermelding")

Koninklijke Nederlandse Botanische Vereniging

P. Sevenster, & W.K.H. Karstens. (1955). Observations on the Proliferation of Stem Pith Parenchyma in Vitro. II. The Internal Structure of Stem Pith Cylinders of Helianthus tuberosus L. cultivated in Vitro. Acta botanica neerlandica, 4(2), 188–192.