冠果草的花部发育——兼论冠果草与近缘属的亲缘关系
FLORALORGANOGENESISOFSAGITTARIA GUAYANENSISSSP.LAPPULA ——WITH ADDITIONALREFERENCETOITS RELATIONSHIPWITH THERELATIVEGENERA
-
摘要: 利用扫描电镜首次对冠果草(Sagittaria guayanensisH.B.K.ssp.lappula(D.Don)Bogin)的花器官发生进行了观察。结果显示:萼片原基以螺旋状方式向心发生,花瓣原基以接近轮状方式近同时发生,并与萼片原基相间交替排列。不存在花瓣-雄蕊复合原基,最外轮6枚雄蕊原基的发生与萼片原基和花瓣原基相交替,并倾向于以两两对萼的形式发生,对萼雄蕊对和对瓣雄蕊对仅仅是这种相间交替排列方式的不同形式；心皮原基或退化心皮原基的发生或多或少地与前一轮原基相交替。观察结果不支持把对瓣雄蕊对作为泽泻科甚至慈姑属花部结构的一般特征；对泽泻目花部结构的一般模式应予以重新修正。在与泽泻科相关属花部发育和结构比较基础上,还探讨了冠果草的系统学地位及与相关属的亲缘关系Abstract: Floraldevelopm ent of Sagittaria guayanensis H.B.K.ssp.lappula(D.Don)Bogin (Alism a- taceae)has been observed under scanning electron m icroscope(SEM).The sepalprim ordia firstinitiates on radiispirally,and a w hirlofthree alternisepalous petalprim ordia form nearly sim ultaneously.Deve- lopm entalstudies confirm thattheexistence of petal-stam en com plex prim ordia isafalse appearanceand do not support that antipetalous stam en pairs are generalcharacteristics offloralconstructure in Alis- m ataceae. Itshows that the first six stam en prim ordia locate at the sites alternate w ith the sepalpri- m ordium and the petalprim ordium,and they are m ore like antisepalous,w hereas antisepalous stam en pairs orantipetalousonesare a secondary nature ofthe alternate arrangem ent.Futhercarpelprim ordium (orrudim entary carpelprim ordium in the m alefloralbud) w ere form ed centripetally,m oreorlessalter- nating w ith the previous ones atsubsequently higher levels.The generaltypes offloralconstructure in Alism ataceae should be revised.Ascom pared w ith the relative genusofAlism ataceae,thecharacteristics offloralconstructure are discussed in relation to the phylogenetic position ofS.guayanensis.
-
计量
- 文章访问数: 1860
- HTML全文浏览量: 0
- PDF下载量: 2565
下载:
