HISTO-ANATOMICAL STUDY OF THE VEGETATIVE ORGANS OF HERACLEUM SPHONDYLIUM SSP. SPHONDYLIUM

This study presents the first comprehensive histo-anatomical characterization of the root, stem, and leaf of Heracleum sphondylium ssp. shpondylium. Transverse sections revealed key structural features across all organs. The root exhibited a circular outline and secondary growth, with a periderm composed of phellem, phellogen, and phelloderm, a cortex containing aerenchyma and secretory canals, and a wide zone of secondary phloem and xylem, both traversed by medullary parenchyma. The stem displayed a layered organization from epidermis to central pith, including a cortex with collenchyma and secretory canals, and collateral vascular bundles forming a ring that defined the transition to the central cylinder. The dorsiventral leaf anatomy featured a two-layered palisade parenchyma on the adaxial surface and spongy parenchyma on the abaxial side. Secretory canals were consistently present in the cortex and vascular regions of all organs, and long, simple, unicellular trichomes with a basal crown of thick-walled cells were found on the leaf surface. These anatomical structures, particularly the secretory canals and trichomes, likely play a key role in the biosynthesis and release of furanocoumarins.