Morpho-anatomy of the Echium plantagineum L. (Boraginaceae) diaspores in relation with water uptake and germination

  • María Laura Molinelli Herbarium ACOR, Faculty of Agricultural Sciences, National University of Córdoba, 5000, Córdoba, Argentina. Chair of Morphological Botany, Faculty of Agricultural Sciences, National University of Córdoba, 5000, Córdoba, Argentina.
  • Rocío Tarifa
  • Patricia Perissé Herbarium ACOR, Faculty of Agricultural Sciences, National University of Córdoba, 5000, Córdoba, Argentina. Chair of Morphological Botany, Faculty of Agricultural Sciences, National University of Córdoba, 5000, Córdoba, Argentina.

Abstract

Echium plantagineum (Boraginaceae) is native to the Mediterranean, it grows from the United States, Mexico, to Brazil, Chile, Uruguay and Argentina. The objectives of this research were: (i) to study the morpho-anatomy of the diaspores of E. plantagineum; (ii) to identify the pathway of water uptake; and (iii) to characterize the germination and the seedling. The morpho-anatomical studies were carried out analyzing semi-permanent and permanent slides of transverse and longitudinal sections of the fruits, the seeds and the seedlings. Histological, histochemical and conventional staining techniques were used for the analysis with stereoscopic, optical and scanning electron microscopy. The water pathway was determined with fast green staining, germination tests were performed and the seedlings were analyzed. The diaspores showed to be formed by the acrescent calyx with the fruit, compound by 4 rough tuberculate mericarps. Each indehiscent mericarp encloses an exalbuminous seed with a thin seed coat and a spatulate embryo with folded cotyledons. Water uptake took place through the protuberance in the abscission scar of the mericarp. Germination was epigeal, the cotyledons were photosynthetically active at the emergence, and a rudimentary developed gemmula was observed. Germination percentage was 66.5 %. The presence of macrosclereids with tannins in the pericarp, neither constitute a barrier for the water uptake nor represent an obstacle for germination.

Published
2020-05-22
Section
Articles