伞形科山芹属8种17个居群的植物花粉形态研究

Research on Pollen Morphologies of Ostericum Hoffm.(Apiaceae) of Eight Species from Seventeen Populations

该研究采用光学显微镜与扫描电子显微镜对山芹属(Ostericum Hoffm.)8种17个居群的花粉形态特征进行观察和分析,为山芹属分类鉴定与属下系统关系研究提供依据。结果显示:(1)山芹属17个居群的花粉类型包含椭圆形、近长方形、超长方形和赤道收缩形4种类型。(2)花粉赤道面观有近椭圆形、近长方形与超长方形,极面观多为三角圆形,少数为三角形。(3)花粉极轴长度为24.7～35.6μm,赤道轴长度为10.6～17.4μm,极轴与赤道轴的比值P/E为1.7～2.5,体积指数(P×E)(1/2)为18.2～22.6。(4)花粉萌发孔均具三孔沟,且多为边萌发孔,角萌发孔较少,沟细长且均匀。(5)花粉赤道区外壁纹饰分为3类,即片状脑纹、长条状脑纹和短棒状脑纹,少数具有颗粒状或疣状的附着物。研究认为,山芹属植物花粉的形状与赤道区外壁纹饰类型存在较高的种内一致性,萌发孔类型、花粉中部是否凸出以及纹饰条纹长度、密集程度、附属物等特征则存在一定的种内差异性;花粉形态特征可为山芹属植物不同层次的分类鉴定与亲缘关系研究提供重要的证据。

We investigated and analyzed pollen morphologies of Ostericum Hoffm.(Apiaceae)of 8 species from 17 populations under light microscopy(LM)and scanning electron microscopy(SEM)in this research,in order to provide evidence for taxonomic identifications and studies of the relationship in this genus.The results showed that:(1)four types of the pollen grains from 17 populations were recognized including ellipse,sub-rectangular,super-rectangular and equatorially constricted shapes.(2)Their shapes of equatorial view were ellipse,sub-rectangular,and super-rectangular,and the shapes of polar view were mostly triangular-rounded,while a few were triangular.(3)The polar axis length(P)is 24.7-35.6μm,equatorial axis length(E)was 10.6-17.4μm,P/Evalue and (P×E)(1/2)fell in 1.7-2.5 and 18.2-22.6,respectively.(4)Tricolporate apertures were observed in all the pollen grains with long and even colpus,in which most species were pleurotreme,yet a few were goniotreme.(5)Under SEM,the materials showed various exine ornamentations in equatorial regions which could be divided into three types,according to their different kinds of sculptures,as flaky cerebroid,long striate cerebroid and brevistriate baculatecerebroid.The surfaces of most grains had no appendage,except a few species contained granular or verrucous appendages.The study suggests that the pollen morphologies of Ostericumexhibited certain intraspecific stabilities both in pollen shapes and exine ornamentations,and also suggests interspecies diversities in aperture types,central protrudents and length,density and appendages of exine ornamentation.In conclusion,these morphological characteristics of pollen could probably present a potential information and significant evidence for a series of research on taxonomic revisions and genetic relationships of Ostericum.