ANGIOSPERMS. 



425 



already said, ran be symmetrically divided by two planes in different ways; the 

 anterior and posterior hahes which are symmetricall)' alike are different from the 

 right and left halves which are also symmetrically alike ; and the general form of the 

 mature flower corresponds to this arrangement of the parts in Dice?itra ; in Fumaria 

 and Corydalis on the other hand the right side is developed differently from the left ; 

 the one produces a spur, the other does not, while the anterior and posterior sides are 

 symmetrical ; in this case therefore the plane of symmetry coincides with the transverse 

 or lateral plane section. In the zygmorphous flowers of some Solanaceae the plane of 



Fig. 352. Zygomorplious flower of C(j/kw 

 removed. B the androecium C the gynaece 

 section of the ovary. F the diagram. Tht 

 stigma, g the style, fk the ovary, d the stair 



nea Schiedectna, one of tlie Gesneraceae. A an entire flower with two sepals 

 Lini. D the coherent anthers enlarged and seen from behind. E transverse 

 letters a denote the anthers, en the connectives, ythe filaments, « the 

 inode developed as a nectary,// the laterally oblique placentas. 



symmetry and the median plane intersect one another at an acute angle ' ; but the 

 large majority of zygomorphous, monosymmetrical flowers are so constructed, that the 

 median plane is at the same time a longitudinal section which divides them symmetri- 

 cally, as for instance in the Labiatae, Papilionaceae, Orchideae, Scitamineae, 

 Delphinium, Aconitum, the Lobeliaceae and Compositae, etc.''' The zygomorphous 

 development is found especially in the lateral flowers of spikes, racemes and panicles, 



^ Such flowers are said to be obliquely zygomorphous ; the expressions median zygomorplious and 

 transverse zygomorphous require no explanation. 



'^ In observations of this kind it is necessary to attend to torsions, such ,ns occur in tlie ovary of 

 the Orchideae, on the flower-stalk of the Fumariaceae, etc. 



