Corolla tube formation in four species of solanaceae

Abstract

Corolla tube formation inSolanum nigrum, Salpichroa rhomboidea, Datura stramonium var.chalybea andNicotiana tabacum cv. Xanthi nc was investigated anatomically.InSolanum, the formation of the lower portion of the corolla tube, including the portion below the stamen insertion and the inserted zones, begins with the extension of the bases of the petal primordia toward the interprimordial regions. The extension of the petal bases is caused by the successive incorporation of the interprimordial regions just beside the bases into the petal primordia by means of the upward growth at those regions. The extending petal bases reach the lower portions of stamen primordia and connect with them resulting in formation of a short tube, which later develops into the lower portion of a corolla tube accompanied by epipetalous stamens.The petal bases extend further, and connect with each other outside the stamen primordia. The upward growth occurs also at the connected regions resulting in formation of the upper portion of a corolla tube. Marginal meristems of the petal primordium differentiate not later than the connection of petal bases. After the connection, marginal meristems and meristems of connected regions become continuous with each other and develop in a similar pattern.In the other three species, the corolla tube is formed in a similar manner as in the species mentioned above. However, the connection of the petal primordia occurs much earlier than the differentiation of their marginal meristems. InSalpichroa andNicotiana, the developmental patterns of the connected region and the corolla lobe margin are different.