Morphological and architectural features of young Nothofagus pumilio (Poepp. & Endl.) Krasser (Fagaceae)

The morphology and architecture of young Nothofagus pumilio plants growing as understorey and in a cleared area were assessed. Length, number of inter nodes, presence of branches and apex condition were registered for each gro wth unit (GU) in the sampled plant. GUs were grouped according to branching order and age of the bearing axis. Understorey plants were seven years old and had a short trunk bearing 2-3 orders of branches; all of their most re cent GUs were horizontal and of comparable size. Plants growing in the clea red area were 10-16 years old and had a vigorous vertical and dominant trun k bearing 4-5 orders of less vigorous, horizontal branches. Plants from the cleared area showed signs of having had comparable-size GUs in all of thei r axes at a younger stage of growth. N. pumilio plants appear to start thei r growth with the production of short GUs in all of their axes irrespective of the light conditions. In contrast, the development of a vertical, vigor ous trunk, seems to be restricted to plants growing in open environments. ( C) 1999 The Linnean Society of London.