明党参花后果实发育的外部形态特征变化

Change of external morphologic features of cremocarp during development after falling of flowers of Changium smyrnioides(Apiaceae)

中国特有伞形科植物明党参（Changium smyrnioides Wolff）花后果实发育过程可分为幼果、中果和熟果3个发育阶段,后两个阶段可分别划分为3个时期。正常成熟的明党参果实为2个分生果完全分离并悬垂的双悬果,属于伞形科中果体轻度背腹压扁、无果棱的类型,并雏形于幼果阶段、成形于中果阶段、完成于熟果阶段;果实中的2个分生果有时有不均等发育现象。花柱及花柱基伴随果体发育并宿存于果体,形成果体与花柱基-花柱的复合体。随果体的增大,果体形状由最初的近陀螺形发育为双肾状长圆形;果棱在幼果和中果阶段时可见,至成熟阶段消失;熟果初期棱槽油管可呈现明显的横隔样结构;果体颜色由幼果期的深绿色变为中果后期的浅绿色,完全成熟时呈褐色或黑棕色。花柱分叉角度从幼果期的60°-90°增大至中果阶段的90°-220°,成熟阶段大于220°;花柱基由圆锥形变为圆台状;幼果、中果和熟果阶段花柱基高度与果体长度的比值分别为1.0-0.8、0.8-0.1和小于0.1。花柱分叉角度和花柱基高度与果体长度的比值可作为判断明党参果实发育程度和阶段的重要标志。

The fruit development process after falling of flowers of Changium smyrnioides Wolff,an endemic species of Apiaceae in China,is divided into young,middle and mature fruit phases.The latter two phases can be further divided into three stages,respectively.The fruit of C.smyrnioides is a cremocarp with two mericarps completely separated and overhung.The mericarp belongs to the slightly dorso-compressed and ribless type,which forms prototype in young fruit phase,takes shape in middle fruit phase and fixes shape in mature fruit phase.Occasionally,the two mericarps in a cremocarp develop unequally.The style and stylopodium develop along with cremocarp body,persist on the mericarp body,and form a complex with mericarp body.With fruit body enlarging,the cremocarp shape changes from first sub-whirligig shape to double kideny-shape long round.The ribs are visible evidently from young to middle fruit phases,while are not visible in mature fruit phase.The vittae in vallecular canal appear obviously the like-trabecula structure in initial stage of mature fruit phase.Fruit color changes from deep green in young fruit phase to light green in middle fruit phase,then changes into brown or dark brown in mature fruit phase.Forked angle of two stylus changes from 60°-90° in young fruit phase to 90°-220° in middle fruit phase,and to greater than 220° in mature fruit phase.The stylopodium shape changes from coniform to truncated cone-shaped.Ratio of stylopodium height to fruit body length in young,middle and mature fruit phases is 1.0-0.8,0.8-0.1 and less than 0.1,respectively.It is suggested that forked angle of stylus and ratio of stylopodium height to fruit body length can be used as important indexes for distinguishing development phase of C.smyrnioides cremocarp.