| Artemisia wudanica, A. halodendron and A. sphaerocephala are all sub-shrubs which belong to sect. Dracunculus of genus Artemisia (Compositae). The first two are inherent species of Horqin sandy land, while, A. sphaerocephala is a species by aerial seeding. They are all important windbreak and sand-fixed plants. In this thesis, the three Artemisia species was studied, which distribute in Wengniute Banner of western Horqin sandy land. The research focuses on the relationship between phenology and environmental factors, flowering phenology, quantitative characteristics, inflorescence configuration. Main conclusions are presented as follows.1. The sprout period of three species was all in the end of February. By late April, A. halodendron entered leaf-expansion period and A. wudanica was in the early May. But the leaf-expansion period of A. sphaerocephala was in mid-May which was later than the first two. After about20-30d, A. wudanica and A. halodendron began squaring successively until the end of May. The development of inflorescences last20d and30d, and then began to bloom. Flowering period of A. wudanica came earliest which was in mid-June. A. halodendron was10days later than A. wudanica which was in late June. However, A. sphaerocephala had a long vegetative growth period about80days and squaring in early August, then blooming in late August or early September. A. wudanica and A. halodendron reached maturing period in mid-October and A. sphaerocephala reached in late October.2. The main climatic factors influencing leaf-expansion period of three species were the average temperature of ten days, the hours and length of sunshine, and the average rainfall of ten days. The main factors which affect squaring period were the hours of sunshine of ten days, the average rainfall of ten days and the average temperature of ten days. The most important factor which affects flowering period was length of sunshine, called photoperiod. The mainly factors which affect fruit maturing period are the average rainfall of ten days, the average temperature of ten days and the length of sunshine. In general, temperature and sunshine are the primary factors effect the phonological phase of three species.3. According to the2012observation, the onset of A. wudanica was18th June at the population level, it was9days earlier than A. halodendron’s(27th June), but A. sphaerocephala’s onset was the latest(30th August). The duration was19days and16days in A. wudanica and A. halodendron respectively, and the overlapping flowering period was10days in two species. But A. sphaerocephala’s duration was14day. In2013, the onset of A. wudanica was16th June at the population level, A. halodendron was on27th June and A. sphaerocephala was on2nd September. The flowering period and process of three species were similar in two years. The three species were all mass-flowering, and the flowering frequencies were all single-peak type. Flowering duration time of the capitulum in A. wudanica and A. halodendron were most5days, but A. sphaerocephala’s was4days. However, the flowering durations of single flowers were all last1d most, and they were opening before10:00every day, delaying the opening in rainy days. The capitulum on the top of secondary inflorescence branches was the first blossom in A. wudanica, and the frequency was to56.3%, other positions had no difference. But the first flowering position of A. halodendron and A. sphaerocephala was near the base one, but the frequency was not high (about10%). The flowering amplitude curve of three species all showed a single peak curve, which A. wudanica showing a normal distribution, A. halodendron being approximate normality and A. sphaerocephala being positive skewness. But flowering process of A. wudanica was the longest (22d), A. halodendron was19d, and A. sphaerocephala was the shortest (16d).4. On the main distinguishing feature, leaves on middle of foliage branches of A. wudanica were obviously longest (5.77cm), followed in order by A. halodendron (4.66cm) and A. sphaerocephala (3.78cm)..The shape of A. halodendron’s leaves was nearly circular; the other two were broadly ovoid. Lobulate wide of A. wudanica (0.85mm) and A. sphaerocephala (0.87mm) were obviously wider than A. halodendron’s (0.71mm). The capitula of A. wudanica were spherical or near spherical, and were drooping with the larger diameter of3.86mm than the other two species. A. halodendron’s capitula were ovoid and upright with the diameter of2.46mm, and capitula of A. sphaerocephala were nearly spherical (diameter of2.24mm) which were drooping or tilted. There were some differences in the shape and size of achene in these three species. Achenes of A. wudanica were moments oblong-obovate (2.01mm in length,0.92mm in width), and A. sphaerocephala’s were elliptic-obovate (2.02mm in length,0.94mm in width). Achenes of A. halodendron were long obovate (1.84mm in length,0.70mm in width) and obviously smaller than the other two.5. The total number of capitula per plant in three species has no significant difference, but the numbers of capitulum in lower part on wooden sticks are less than other parts. On the inflorescence structure, the number of edge female flowers of A. wudanica’s capitula was5-11pieces, more than A. halodendron (3-7pieces) and A. sphaerocephala (2-6pieces). The number of bisexual flowers of A. wudanica was11-22pieces which were similar to that in A. halodendron (6-21pieces), and A. sphaerocephala’s number was the least (5-14pieces). The angles of secondary inflorescence branches of A. wudanica were less than30°which led the reproductive branches arranged in a narrow conical, but it were arranged as an expanded conical shape with the angles of30°-35°in A. halodendron, and the A. sphaerocephala’s were greater than50°, so the reproductive branches arranged as a large expanded conical shape. |
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