Morpho-anatomy of the Echium plantagineum L. (Boraginaceae) diaspores in relation with water uptake and germination
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.
This work is licensed under a Creative Commons Attribution 4.0 International License.
Articles published by TSP are under an Open Access license, which means all articles published by TSP are accessible online free of charge and as free of technical and legal barriers to everyone. Published materials can be re-used if properly acknowledged and cited Open Access publication is supported by the authors' institutes or research funding agencies by payment of a comparatively low Article Processing Charge (APC) for accepted articles.