Seedlings of English oak (Quercus robur L.) and cork oak (Quercus suber L.) grown in minirhizotrons have (i) semiplagiogeotropic lateral roots which reorient their tip when placed in certain positions; their growth is very brief; (ii) taproots which are strongly orthogeotropic when they are short and weakly orthogeotropic when they are 2 m long; (iii) replacement taproots, appearing after a decapitation of the taproot, which are either orthogeotropic or slightly oblique. The orthogeotropic caracteristics of taproots and replacement taproots seem difficult to alter.Deviating, slowing the growth, blocking, or drying the tip of the taproot induces various transformations of lateral roots. Axial growth, radial growth, growth of the ramifications, and geotropism of the lateral roots can be changed separately, but in a certain order. Growth correlations within the root system of young oaks are compared with those already studied in the root system of Theobroma cacao L. The nature of the correlations is discussed.

In order to study some biological active products, phytochemical investigation of the stem bark of Turraeanthus africanus have led to the isolation of a novel compound 1, a new benzoic acid derivative, named turraeanthin C, and two known compounds sesamin (2) and stigmasterol. The structures of these compounds were established by spectral analysis, including two-dimensional nuclear magnetic resonance. The extract and the isolated compounds 1 and 2 showed noteworthy activity against Toxoplasma gondii intracellular parasite in mammals.The evaluation of medicinal plants used in the preparation of folk remedies has provided modern medicine with effective pharmaceuticals for the treatment of diseases caused by various parasites. Parasites are a very important problem in medical and veterinary fields. They are widespread in tropical regions and in other part of the world where HIV infections are high as opportunist parasites. The discovery and development of anticoccidial compounds are effective methods for the prevention and treatment of these problems. Toxoplasma gondii is an obligate intracellular parasite that is able to infect a wide range of mammalian and avian species [1]. In humans, Toxoplasma infections are widespread and can lead to severe disease in individuals with immature or suppressed immune systems. Consequently, toxoplasmosis became one of the major opportunistic infections of the AIDS epidemic [2]. Toxoplasmosis can also affect T. gondii negative women during pregnancy, and so it is a serious threat for embryos.