1916] The Ottawa Naturalist. 141 



but stunted P. trijoiiata and P. racemosa, whilst the rest ap- 

 peared soinewhat puzzhrg and intermediate between the two. 

 We determined to prepare a large series of specimens to faci- 

 litate a thorough study, but, alas! the next morning the marsh 

 was found neatly mowed, and the Prenanthes were no more. 



Later study and comparison with type in the Gray Her- 

 barium have shown our doubtful forms to be equivalent to P. 

 mainensis Gray. There can be hardly any doubt now that 

 the so-called P. mainensis is a natural hybrid : P . racemosa yi 

 P. trijoiiata. Gray's text reads as follows: "About two feet 

 high, leafy up and into the panicle; leaves nearly those of P. 

 racemosa, but thinner and less glaucous; the radical ovate, 

 commonly with abrupt or rounded base ; upper, subtending clus- 

 ters of the interrupted narrow thrysus; heads all drooping both 

 before and after anthesis, resembling those of the following 

 species (P. virgata Michx). Shore of the St. John's River at 

 St. Francis, North Maine, Pringle. Growing with or near P. 

 racemosa. And a looser form of the latter, "very common on 

 the St. John's River," (Goodale) is somewhat between the 

 tAvo; so that this may be a hybrid between P. racemosa and P. 

 serpentaria." C^) 



It should be borne in mind that when these lines were 

 written (1886), P. trijoiiata had not yet been separated from 

 P. serpentaria. From the description of Gray it appears that 

 the plant named by him P. mainensis was an extreme form of 

 the hybrid, differing from the "looser form of P. racemosa'-' 

 only quantitatively, and that both are but distant terms of a 

 Mendelian series. 



We will now give the result of our own study based on the 

 comparison of 15 specimens of P. racemosa, 20. of P. trijoiiata, 

 and 8 of P. mainensis. 



Stem. 



An important reduction in size is first noticeable, which 

 is doubtless a response to the semi-halophytic habitat. In nor- 

 mal conditions P. racemosa reaches fully 2m., whilst here its 

 maximum is 30cm. P. trijoiiata generally grows to a height 

 of l.SOm., and exceptionally to 3m. ; in this locality no specimen 

 higher than 32 cm. was found. 



It is well known to breeders, as well as to sttidents in 

 hybridism, that crosses between nearly related forms are more 

 vigorous than either parent. The following tabulation will 

 emphasize the law as applied to the present case: — 



*Gray, Asa, " Synoptical Flora," I., 433, 1886. 



