Leaves of vascular plants are arranged regularly around stems, a phenomenon known as phyllotaxis. A constant angle between two successive leaves is called divergence angle. On the one side, the divergence angle α0 of an initial pattern of leaf primordia at a shoot apex is most commonly an irrational number of about 137.5 degrees, called limit divergence. On the other side, the divergence α of a...

twenty-two bread wheat cultivars along with susceptible (sholeh) and resistant (azadi) control cultivars were evaluated for resistance to russian wheat aphid of two growth stages including seedling and stem elongation in greenhouse. five adult aphids per plant were used for infestation. leaf chlorosis at seedling and stem elongation stages and leaf rolling at seedling stage were measured. other...

Stem length and leaf area of current-year shoots were measured in saplings of eight broad-leaved evergreen tree species growing under a forest canopy. Stem length varied over a range of one to two orders of magnitude within each species. In all species, both the number of leaves and the mean stem length between successive leaves were greater in longer shoots. Mean leaf size and stem length were...

1. In Bryophyllum calycinum two apical leaves suppress the shoot formation in all the dormant buds situated basally from the leaf; one apical leaf suppresses the shoot formation in the basal buds situated in the same half of the stem where the leaf is, and, if one-half of the petiole of such a leaf is removed, the growth of basal buds in one quadrant of the stem is suppressed. 2. This inhibitor...

Tomato (Lycpoersicum esculemtum) belongs to the Solanaceae potato family and is an important crop plant. It is relatively resistant to salinity, but in the saline environment growth and production of the plant significantly reduces. On the other hand, the presence of mycorrhiza fungus can improve the adverse effects of salinity. A factorial experiment in a completely randomized design with thre...

We examined the effects of artificially altering leaf angle of the tropical tree species Acacia crassicarpa (A. Cunn. ex Benth., Fabaceae) on light interception, leaf temperature and photosynthesis in the wet and dry seasons of tropical Australia. Reducing leaf angle from the natural near-vertical angle (90 degrees ) to 67.5, 45, 22.5 and 0 degrees greatly increased light interception and leaf ...

The importance of high TCR diversity of T regulatory (Treg) cells for self-tolerance is poorly understood. To address this issue, TCR diversity was measured for Treg cells after transfer into IL-2Rbeta(-/-) mice, which develop lethal autoimmunity because of failed production of Treg cells. In this study, we show that high TCR diversity of pretransferred Treg cells led to selection of therapeuti...

Ginseng root is used more often than other parts such as leaf stem although extracts from ginseng leaf-stem also contain similar active ingredients with pharmacological functions. Ginseng's leaf-stems are more readily available at a lower cost than its root. This article reviews the pharmacological effects of ginseng leaf-stem on some diseases and adverse effects due to excessive consumption. G...