Deciduous trees shed their leaves usually as an adaptation to a cold or dry season. Most tropical rainforest plants are evergreens, replacing their leaves gradually throughout the year as the leaves age and fall, whereas species growing in seasonally arid climates may be either evergreen or deciduous.
This page describes the reactions of the Period 3 elements from sodium to argon with water, oxygen and chlorine. Sodium has a very exothermic reaction with cold water producing hydrogen and a colourless solution of sodium hydroxide. Magnesium has a very slight reaction with cold water, but burns in steam.