| Aquilaria sinensis (Lour.) Spreng. is a endemic medicinal tree only found in China, which is listed as China'sⅡprotected wild plants. In this paper, the distribution of A. sinensis (Lour.) Spreng. was investigated, and their biological characteristics were studied with a view of providing necessary biological basis to rationally develop the valuable resources, but also for the artificial cultivation of A. sinensis in the future. This research can also provide essential scientific reference and biological basis for breeding. The main results are as follows:1. The authors drew the distribution map of A. sinensis by consulting herbarium specimens of A. sinensis and related documents, field surveys and telephone interviews, and the result shows that A. sinensis naturally distributes in Guangdong Province, Guangxi Province, Hainan Province, Yunnan Province, Hong Kong and Macao Special Administrative Region of China. There are some of artificial cultivation in Taiwan Province, Fujian Province, Sichuan Province and the Jinsha River valley.2. Numerous methods were used to study the cross-section of leaves, stomatal distribution and stomatal density, the three sections of wood, the types of vessel and other basic biological characteristics, the results showed that:(1)The leaves of A. sinensis are typical bifacial leaf; stomas only distribut on the lower surface of leaf, guard cells are kidney-shaped, stomata's average length is 22.1±1.4μm, the average width is 14.3μ1.6μm and the density is about 135±19 per square millimeter. (2)The main vein vascular bundle of leaf is two-ductile-type and arranged in circular ring, between the xylem and pith is the more developed included phloem. (3)There are island-like distributed included phloem on the cross-section of the timber with medullary rays mostly separated, xylem rays are non-overlapping on the string-section with mostly belong to type III, and raycells arrange in horizontal band on the radial-section and raycells are rectangular. (4)There are various types of vessel, mostly are fine long tubes, a few are coarse and short form; some ends with thick tails, some vessel have one end non-tail and another end tailed, some with remnanted tails while the others have no taisl at all. Vessel elements are single perforation.3. The authors investigated microsporogenesis and male gametophyte development processes of A. sinensis, the results show that:(1)Microsporogenesis and male gametophyte development processes are normal, the anther has four chambers and the pollen sac wall consists of four layers those are epidermis, endothecium, middle layer and tapetum; the tapetum is of a glandular type, The formation of anther wall shows a dicotyledonous type. (2)Cytokinesis occurs simultaneously with meiosis in a microspore mother cell, and the formed tetrads are mostly tetrahedral while some are symmetrical. The mature pollen grains are of a binuclear type. (3)Using a scanning electronic microscope (SEM) to observe the mature pollen grains, which appeared spherical shape with their surface made up of blunt-triangular projected pillars. The germination pores of the pollen were difficult to observe because of their small size and unclear edges. (4)The structure of pistil is observed, the authors found that A. sinensis is composed of 2 carpets complex pistil,2 carpels 2 ventricular locule, each room with 1 erect ovule, and ovule with two layers of integument. |
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