Carbohydrate fractionation of two congeneric Phlomis species from different microhabitats at Saint Katherine and the western Mediterranean coast of Egypt

Two Phlomis species occur in Egypt: P. aurea (Decne.), endemic to Sinai region and P. floccosa (Don.) in the western Medi-terranean coast. The carbohydrate composition of plants varied according to the species, microhabitat, and organ. Soluble sugars (SS) were in the order: leaves > flowers > stem in the two species, with higher levels in P. aurea than P. floccosa. By contrast, insoluble sugars (IS), being comparable in the two species, were in the order stem > flowers > leaves. Uronic acids constituted the major sugar fraction in the two species, with higher levels in P. aurea than P. floccosa and different organ allocation in the two species. By contrast, monosaccharide and disaccharide fractionations varied in the two species. Whereas arabinose and xylose were the predominant monosaccharides in SS of P. aurea, fructose and mannose predominated in P. floccosa. Likewise, whereas IS of P. aurea lacks galactose, with high levels of xylose and arabinose the reverse was true for P. floccosa. Disaccharides within SS of P. aurea were highest in flowers and least in leaves with the predominance of sucrose over maltose, but the reverse was true in P. floccosa. As for IS, sucrose surpassed maltose in both species. Stachyose was the only oligosaccharide detected, with contrasting distribution in the two species. Sugar alcohols in SS were higher in the foliage of the two species than the flowers with the predominance of mannitol over sorbitol, but in the case of IS, only mannitol exists, with contrasting organ allocation in the two species.