5.56 



PHANEROGAMS. 



plane coincides with a longitudinal section which divides the flower symmmetrically ; as 

 for instance in Labiatce, Papilionacese, Orchideae, Scitamines, Lobeliacese, Compositae, 

 Delphinium, and Aconitum^ The zygomorphic development is especially prevalent in 

 the lateral flowers of spicate, racemose, or paniculate inflorescences ; but is found also 

 in those that are cymose and that have all the flowers terminal (Labiatae and Echium). 

 It seems as though the vigorous development of the principal rachis of the entire 



inflorescence — whether the final rami- 

 fications are cymose or not — often de- 

 termines a zygomorphic development of 

 flowers, as is shown in Labiatae, Scita- 

 mineae, and Aesculus. The formation 

 of a vigorous pseud -axis appears to 

 exercise a similar influence in the case 

 of sympodial inflorescences (as in 

 Echium). 



The Fruit of Angiosperms is the ma- 

 ture ovary w'hich contains the ripe seeds 

 and has undergone physiological changes 

 as the result of fertihsation. The style 

 and stigmas are frequently deciduous (as 

 in Gucurbita, Grasses, &c.). Some of 

 the ovules not unfrequently disappear, 

 and the number of seeds is thus less 

 than that of the ovules. When all the 

 ovules of one or more loculi of a multi- 

 locular ovary disappear in the process of 

 ripening, only the fertile loculus con- 

 tinues to grow ; the others become 

 partially or entirely suppressed, and can 

 be recognised only with difficulty or not 

 at all. A multilocular ovary may thus 

 produce a unilocular, and often a one- 

 seeded fruit. Thus from the trilocular 

 ovary of the oak, each loculus of which 

 contains two ovules, results a unilocular 

 one-seeded fruit, the acorn. A less com- 

 plete disappearance of two or four loculi 

 together with their ovules occurs in the 

 tri- or quinqui-locular ovary of the lime, 

 the fruit usually containing only one 

 seed. 



Parts of the flower again which do 



not belong to the gynaeceum, or even not 



to the flower, undergo changes resulting 



from fertilisation. The entire structure 



which is thus formed may be termed a 



Pseiidocarp, and may be composed of a single fruit or of a number of true fruits 



together with the surrounding parts which have undergone peculiar development. Thus, 



for example, the strawberry is a pseudocarp, the axial part (or receptacle) of the flower 



Fig. 387.— Zygomorphic flower of Orchis maculata: A bud 

 divided symmetrically through the middle ; B transverse section 

 of the bud; C horizontal section of the ovary: D entire mature 

 flower, one of the lateral perianth-leaves having been removed ; 

 JT mother-axis of the flower; 6 bract, j outer, / inner perianth- 

 leaves — the posterior one / becomes the labellum, a the single 

 anther, st staminodes, gs gynostemium, // pollinium, h its viscid 

 disc, sp spur of the labellum, ythe inferior ovary, twisted in D 

 (compare the diagram Fig. 379, p. 526). 



^ In observations of this kind attention must be paid to torsions, such as occur in the ovary 

 of Orchidex, the flower-stalk of Fumariacere, the laburnum, cS:c. 



