60 



compatible. According to Clusius {Plant arum Historia, p. 

 137) this species was commonly in cultivation in middle 

 Europe as early as 1601. Since then its cultivation has been 

 extended over large areas of Europe and America, and in many 

 sections it has escaped from cultivation and is spreading widely, 

 purely by vegetative means of propagation. 



It can be predicted with confidence that a search in the region 

 where H. fulva is native and wild will reveal plants that are 

 producing seed or at least strains that will prove compatible 

 with the self-incompatible strain now found in the United 

 States. Focke showed that such a condition as this existed in 

 Lilium bulbiferum. After failing for years to get seed by sell- 

 ing and crossing plants of this species obtained from various 

 parts of Germany, he obtained wild plants from the native 

 habitat in Tyrol and these he found compatible with strains 

 that previously failed to produce seed. 



It has very generally been held that the seed sterility of such 

 plants as Hemerocallis fulva, Lilium bulbiferum, Lilium ti- 

 grinum, etc., is "correlative." That is, the vegetative organs of 

 propagation are conceived to divert and utilize the available 

 food so that the embryos in seeds are virtually starved to 

 death during stages in development, or perhaps organs are 

 so poorly nourished that they do not function previous to fer- 

 tilization. But evidence is increasing to the effect that seed 

 production in these plants is relative and depends on whether 

 Fertilizations arc compatible, quite as is the case in numerous 

 species of plants that are naturally propagated only by seen-. 

 The experimental proof of this is sometimes difficult to obtain 

 in the plants that arc propagated vegetatively. 



When self-compatible and self-incompatible plants are touna 

 and the latter prove to be highly seed-producing in certain 

 crosses, as i> the case with Hemerocallis flava, the evidence of 

 incompatibilities is clear. The American strain of Hemero 

 callis fulva has sex organs that do function to some extent in 

 certain inter-specific crosses and will, undoubtedly, produce 

 abundant seed when it can he tested with stocks from a (lit- 



