94 Macfarlatit — Obscn'atious on Some Hybrids 



D. hybrida is rather strongly incoiled, as in the latter parent. 

 The blooms average lo, and these are set in a rather scattered 

 sub-secund manner along the false axis. 



{d^ Period of Blooming. — In my paper on " Plant Hybrids"* 

 I advanced a considerable body of facts to prove that the 

 flowering period of many hybrids is ver^' exactly intermediate 

 between the periods of the parents, while other hybrids show 

 a decided divergence toward one parent. It has not been 

 possible to do more in the present study than to ascertain 

 approximately the relative period of blooming. From a study 

 made at several localities in New Jersey during the past season, 

 it was learned that the first blooms of D. filiformis opened on 

 June 7—10, and by June 28 the terminal flowers of the cyme 

 were open. When collected on June 30, a number of the 

 lower flowers on the more vigorous hybrid plants had already 

 passed, while the lowest flowers on small plants and the lower 

 middle flowers on strong plants were fully open. The plants 

 continued to flower in the University greenhouses till August 3. 

 As already noted, when plants of D. intermedia were gathered 

 the involute flower stalks were just unrolling, and later obser- 

 vation showed that this species begins to bloom about July 3, 

 and continues until about August 1 5. In attempting to account 

 for the origin of the patch of hybrid plants, therefore, it seems 

 extremely likely that a late bloom of D. filiformis, and an 

 early bloom of D. intermedia had been concerned in the polli- 

 nation process. The limited observations just recorded point 

 to D. hybrida as a form which blooms at a period between those 

 for the parent species. It should be said, however, that the 

 writer and another member of the party succeeded in obtain- 

 ing some four blooms of D. filiformis on as many plants as late 

 as August 10. That they were entirely out of season was 

 proved by hundreds of surrounding plants having their cap- 

 sules in an advanced state of maturity. 



{e) Sice and Color of the Blooms. — Those of D. filiforinis 



*Trans. Roy. Soc. Edin.. Vol. XX.WIII. 



