208 



THE FLOWERING PROCESS 



2. Day-neutral, quantitative promotion by low temperature. These plants 

 will flower under virtually any conditions, but they flower sooner if they 

 receive a low temperature treatment. 



Allium cepa, H. 12 (non-inductive response) A variety of onion 

 Lathyrus odoratus ? C. 207 Sweet pea 



Lens culinaris ?, C. 207 Lentil 



Pisum sativum, H. 13, C. 207, 218 Garden pea variety 



Pelargonium hortorum, H. 85 Fish geranium 



Vicia Faba ? C. 207 Broad bean 



Vicia sativa ? C. 207 Vetch 



Viola tricolor ? H. 93 Pansy 



3. Day-neutral, promotion by high temperature. 



Fuchsia hybrida, H. 83 Fuchsia 



Oryza sativa, H. 38 Summer rice 



4. Day-neutral, promotion by temperature alternation (Thermoperiodism). 



Capsicum frutescens, H. 14 Pepper 



Lycopersicon esculentum, H, 21, C. 206; Tomato 

 Fig. 1-A 



5. Day-neutral, low temperature required. (Vernalization). Members of 

 this category which can be placed here without any question refute a 

 long-held idea that all cold-requiring plants also required long-days. It 

 may still be true that all cold-requiring plants which respond as seeds or 

 seedlings require long days. The plants listed here must all reach some 

 stage of vegetative growth before they will respond to cold. A few species 

 in which the day-length requirement is in doubt are marked by a question 

 mark. 



Agrimonia eupatoria, C. 212 

 Apium graveolens, II. 8, C. 203 

 Arabidopsis t ha liana ? C. 200 

 Cardamine amara, C. 212 

 Centaurium minus ? C. 222 

 Draba aizoides, C. 211, 218 

 Draba hispanica, C. 211 

 Eryngium variifolium C. 212, 222 

 Erysimum spp., C. 212, 218 

 Euphorbia lathyris, C. 205, 222 

 Geum urbanum, C. 208, 210, 218 



„ bulgaricum 



„ intermedium 



„ canadense 



„ album 



„ macrophyllum 



Agrimony 



Celery 



Variety "Stockhohn' 



Bittercress 



Centaury 



Whitlow-grass 



Eryngn 

 Wallflower 

 Caper spurge 



