THE OVULE 



277 



placenta or in the carpel wall (Fig. 1060- In some parasites, tlie 

 gynoecium — usually syncarpous, with inferior ovary — is so greatly sim- 

 plified that its structure is determined only with difficulty. The im- 

 portance o£ the recognition that some extremely simple angiosperm 

 flowers may have "naked ovules" (without integuments) or no obvious 



Fig. 106. Diagram illustrating hypothetical derivation of the Balanophora flower, a, 

 normal, unreduced flower with free central placenta; b, ovules reduced in size, 

 nucellus small, flat — Thesium; c, ovules not differentiated on placenta, their nucellj 

 merged with placental epidermis — Osyris, Santalum, Myzodendron; d, placenta re- 

 duced to mound or nipple, nucellus lost — Arceuthobium, Helosis; e, nipple reduced 

 — Korthahia; f, embryo sacs on floor of ovarian chamber — Visciim, Dendropthoe; 

 g, h, embryo sacs reduced to one at base of carpellary wall — Scurrula; i, solitary 

 embryo sac embedded in reduced carpel — Balanophora. (After Fagerlind.) 



