Several herbaceous species from "cerrado" (savana like vegetation) have thickened subterranean systems, which may be of root and/or stem nature. These systems have bud shoot-forming potential, providing the sprout of new shoots after an adverse period, like a severe drought or a burning. The verification of the subterranean systems nature is extremely important to the correct terminology usage. This work aimed to present information about subterranean systems morphology and anatomy of Calea verticillata and Isostigma megapotamicum, placing emphasis on the shoot-buds development. The subterranean systems were collected from "cerrado" areas of São Paulo State. The anatomical structure in C. verticillata is of both stem and root nature, with self-grafting of both shoots and roots, whereas in I. megapotamicum, the anatomical structure is caulinar, with self-grafting of shoots. Both species are composed of xylopodium with a high bud shoot-forming potential, whose buds are exclusively formed in the cambium. Secretory ducts occur in these species. The microchemical test, accomplished with Sudan black B, stained the oily nature of the secretion. Crystals of inulin were visualized by polarized light in I. megapotamicum. The high bud shoot-forming potential, present in the subterranean systems of both species here analyzed, improves their survival perspectives when they are submitted to the "cerrado" adverse conditions, by providing the sprouting of new shoots in favourable periods.
anatomy; buds; cerrado; storage; xylopodium
