榆林沙区黑沙蒿花粉二型性特征观察

以毛乌素沙地南缘榆林沙区的黑沙蒿为研究对象，采用扫描电镜（SEM）显微技术，对其花粉形态特征进行详细的观察描述。结果表明，黑沙蒿花粉粒属单粒小型花粉，具有蒿属植物花粉的共性特征，属于较为进化物种的花粉形态，同时其花粉粒二型性特征亦比较突出。长球形和圆球形2种形态不同的花粉粒，同时存在于同一花药中，长球形花粉粒极轴长(P)23.43（20.10～24.91）μm，赤道(E)轴长16.93（15.81～17.32）μm，P/E=1.38，极轴与赤道轴长度差异显著（P<0.05），赤道面观椭圆形；圆球形花粉粒极轴与赤道轴近等长，极轴长17.56（16.11～18.43）μm，赤道轴长17.10（15.99～18.01）μm，P/E=1.03，极轴与赤道轴长度差异不显著（P>0.05），赤道面观圆球形；经T检验，2种形态花粉粒的极轴与赤道轴长度比值P/E，差异达显著水平（P<0.05）。2种形态花粉萌发器官都具3孔沟，但长球形花粉的沟深而细长，边缘整齐光滑，内孔深陷，沟间稍窄，极区面积较小；圆球形花粉的沟较浅较短，沟缘粗糙，内孔外突，沟间较宽，极区面积较大；外壁表面纹饰都为退化小刺与颗粒状纹饰的组合，但刺的分布、基部大小及刺间颗粒的大小和排列等有所差异。样本中长球形花粉粒占比为64.1%，圆球形花粉粒占比为35.9%。

Observation on the Characteristics of Pollen Dimorphism of Artemisia ordosica in Yulin Sandy Area

Taking Artemisia ordosica in Yulin sandy area on the southern edge of the Mu Us Sandy Land as the research object,the morphological characteristics of its pollen were observed and described in detail by scanning electron microscopy (SEM).The results showed that the pollen grains of A.ordosica were single-grain with small pollen,which had the common characteristics of Artemisia plant genus and belonged to the more evolved species in pollen morphology.The pollen exhibited the characteristics of dimorphism.Two kinds of pollen grains with different shapes,prolate and spherical,existed in the same anther.The prolate pollen grains had a polar axis length of (P) 23.43 (20.10-24.91) μm and an equatorial axis length of (E)16.93 (15.81-17.32) μm,P/E=1.38,the length of polar axis and equatorial axis were significantly different (P<0.05),elliptical in equatorial view; spherical pollen grains were nearly equal in length to the equatorial axis,polar axis length was 17.56 (16.11-18.43) μm,equatorial axis length was 17.10 (15.99-18.01) μm,P/E=1.03,no significant difference between the lengths of polar and equatorial axes (P>0.05),spherical in equatorial view; T-test showed that the difference in the lengths of polar and equatorial axes of the two types of pollen grains reached a significant level (P<0.05).The germination organs of the two types of pollen had 3-hole grooves,but the grooves of the prolate pollen were deep and slender,the edges were neat and smooth,the inner holes were deep,the grooves were slightly narrow,and the polar area was small.The grooves of the spherical pollen were shallower shorter with rougher groove edges,protruding inner holes,wider grooves,and larger polar area.The outer wall surface decoration was a combination of degenerate small spines and granular decorations,but the distribution of spines,the size of the base and the particles between the spines were different.There were differences in size and arrangement.The proportion of oblong pollen grains in the sample was 64.1%,and the proportion of spherical pollen grains was 35.9%.