xxii CONTENTS. 



CHAPTER III. 



Hetbrosttlkd Dimohphic Plants — continued, 



Linum grandiflorum, long-styled form utterly sterile with own- 

 form pollen — Linum perenne, torsion of the pistils in the 

 long-styled formal one — Homostyled species of Linum — Pul- 

 monaria officinalis, singular difference in self-fertility between 

 the English and German long-styled plants — Pulmonaria 

 angustifolia shown to be a distinct species, long-styled form 

 completely self-sterile — Polygonum f agopyrum — Various other 

 heterostyled genera — Rubiaceae — Mitchella repens, fertility of 

 the flowers in pairs — Houstonia — Faramea, remarkable differ- 

 ence in the pollen-grains of the two forms; torsion of the 

 stamens in the short-styled form alone ; development not as 

 yet perfect — ^The heterostyled structure in the several Rubi- 

 aceous genera not due to descent in common . Page 81-136 



CHAPTER IV. 



Heterostyled Tbimobphic Plants. 



Lythrum salicaria^Description of the three forms — Their power 

 and complex manner of fertilising one another— Eighteen dif- 

 ferent unions possible — Mid-styled form eminently feminine 

 in nature — ^Lythrum Grsefferi likewise trimorphio — ^L. thymi- 

 folia dimorphic — li, hyssopifolia homostyled — Nesaea verti- 

 cillata trimorphic — Lagerstrcemia, nature doubtful — Oxalis, 

 trimorphic species of — O. Valdiviana — 0. Regnelli, the illegiti- 

 mate unions quite barren — 0. speciosa — O. sensitiva — ^Homo- 

 styled species of Oxalis — Pontederia, the one monocotyledonous 

 genus known to include heterostyled species - . . 137-187 



CHAPTER V. 



Illegitimate Offspring of Heterostyled Plants. 



Illegitimate offsfiring from all three forms of Lythrum salicaria — 

 Their dwarfed stature and sterility, some utterly barren, some 



