This paper aimed at determining, the area of main tissues of leaves (blade and sheath) and stems of Axonopus scoparius and Axonopus fissifolius cultivars, during two growing stages. A completely randomized design with two treatments (6 and 20 weeks of growing) and five replicates was used. The vascular lignified+sclerenchyma tissue was found in higher concentration in the limbo and the stem, and next in the keel and the sheath. With maturity, there was an increase in lignin deposition in most tissues of A. scoparius studied, and primarily in the stem. This was not observed in A. fissifolius cultivars. The largest epidermic tissue area was found in limbo, reaching more than 20% in A. scoparius and 16% in A. fissifolius cultivars. The greater area of epidermic and lignified tissue present in leaf fractions of A. fissifolius, represent additional barriers to ruminal digestion, compared to A. scoparius leaves. The parenchymatic tissue occupied a large area of the stem (over 80%), mainly in the first harvest. As grasses became older, the parenchyma area reduced, while the lignified area increased. It was concluded that the anatomy of the several plant organs is not an effective parameter for differentiating between cultivars of A. scoparius and A. fissifolius species.
forages; grasses; lignin; plant anatomy; ruminants
