Study On Biological Characteristics And Propagation Of Acer Trialatum

Acer trialatum L .L.Deng, K. Y .Wei et G .S .Fan, sp .nov., is a newlydiscovered and nominated species belonging to genus Acer, family Aceracae. It differs from other species of genus Acer because of its three-winged fruits. Up to now, only a single plant of this species has been found in the teaching quarter of Southwest Forestry College, northeast of Kunming. To understand its properties and to expand its population, the morphological traits and biological characteristics, growth rhythm, together with propagation measures including tissue culture, cottage propagation and air layering of the of Acer trialatum L .L.Deng were studied.Compared with other species in genus Acer, Acer trialatum has its own particularity in biological characteristics. It was showed by the observation that the buds sprouted in mid of March, then the leaf buds unfolded and new shoots grew afterwards. There were twice shoot sprouting each year and therefore spring shoots and autumn shoots formed respectively, and the average annual growth of branches was 20cm to 40cm in length. The growth period of leaves lasted for about 20d, the mature size of leaves was 4cm wide and 7.5cm long. The flowers of Acer trialatum included both monosexual flowers and hermaphrodite flowers. The flower buds sprouted seven days' earlier than the leaf buds , and the full blooming period appeared at the beginning of April. Since the blooming periods of male and hermaphrodite flowers did not overlap, the pollination insemination process could not be completed, and the wing fruits did not produce seeds inside.The flower's morphological traits of Acer trialatum also had its particularity. The stigma of female flower was divided into 3 parts and the ovary had 3 locules. In late April, the ovary expanded and 3 wing fruits developed without seeds. The fruits ripened morphologically at the beginning of November. The leaves began to change color and then shed in mid November, and the tree started to be in dormancy at the beginning of December.The pollen grains of Acer trialatum were long spherical in shape and circular with 3 lobes in polar view. The mean size of the pollen was 21.2(19.8-22.7) μm×30.7(28.6-33.5)...