Abstract

We evaluated the effects of the leaves, “pine” or “head” (plants without leaves) age of Agave atrovirens on the epidermal, parenchyma and fibrillar microstructure as possible maturity indicators, since plant age is a determinant factor of the concentration of inulin. Samples were taken from three, six and nine year-old plants, and observations were made with scanning electronic microscopy (SEM) and light microscopy (LM). The results showed that the isolated cuticular membrane (ICM) microstructure in the agave plant changes considerably with the age, becoming harder and allowing the mature plant to avoid excessive water loss, on the other hand, the increased size of the suprastomal cavity makes the respiration process more efficient in older plants. The agaves present the three main types of calcium oxalate crystals reported for monocotyledons (druses, raphides and styloids). The plant age is an important factor in the identification of calcium oxalate crystals because it is only in six year-old plant that all three types were identified. However, the druses are present only in the cuticular membrane (CM), while the styloids and raphides are distributed on the parenchyma and chlorenchyma. The fibrillar structures in agave are modified with age such thatagave can support severe hydric stress and the storage of soluble carbohydrates.

Key words: Crystals, calcium oxalate, fibrillar, druses, raphides, styloids.