542 



SCIENCE 



[N. S. Vol. XXVII. No. 692 



-" The Present State of tlie Study of the Flora 

 of the District of Columbia." 



The last paper on the program was by Mr. 

 Charles J. Brand, of the Bureau of Plant 

 Industry, who discussed a new variety of 

 alfalfa (Medicago sativa L. var. poUa Brand) 

 based on plants grown from seed of Peruvian 

 .origin, quite distinct from forms of the species 

 hitherto known. Inasmuch as the plant prom- 

 ises to be of considerable agricultural impor- 

 tance, Mr. Brand raised the question of the 

 desirability of applying varietal names in the 

 taxonomic sense to distinct forms of our im- 

 portant crop plants. The paper, which in- 

 cluded a discussion of previously recognized 

 varieties, aroused an interesting and spirited 

 -discussion. 



W. E. Safford, 

 Corresponding Secretary 



THE TORREY BOTANICAL CLUB 



The club was called to order on February 

 :26, 1908, at the Museum of the New York 

 Botanical Garden at 3:45 p.m. Ten persons 

 were present. 



The scientific program was as follows: 

 Bemarhs on the Genus Boletus: William A. 



MURRILL. 



This paper will be published in the March 

 (1908) number of Torreya. 



JSome Fern Hybrids: Ealph C. Benedict. 



The object of this paper was to present gen- 

 eral facts regarding fern hybrids, to indicate 

 the apparent significance of the facts, and to 

 show examples of some native hybrids. 



The literature on the subject seems to be 

 very scanty, and consists principally of scat- 

 tered descriptions of natural and horticultural 

 hybrids. Lowe (" Fern Growing ") has given 

 a general discussion of the subject, but his 

 work is of a horticultural, rather than of a 

 scientific, value. The most conclusive experi- 

 ments are those carried on by Miss Margaret 

 Slosson, in which she reproduced culturally 

 Asplenium ehenoides {A. platyneuron X Camp- 

 tosorus rhizophyllus) and Dryopteris cristata 

 X marginalis Davenport, two suspected hy- 

 brids, which occur in nature. Recently, at 

 Jeast one more cross has been artificially pro- 



duced by Mr. Amedee Hans, of Stamford, 

 Conn., between Dryopteris Filix-mas and D, 

 marginalis. This, however, has not yet been 

 found wild. 



Study of these three authenticated hybrids 

 shows that they agree in general with the 

 hybrids of some flowering plants. They are 

 sterile, usually larger than the parents, some- 

 times abnormal, and in many characters inter- 

 mediate to a greater or less degree between 

 the parent species. In view of these facts, it 

 seems reasonable to interpret as hybrids other 

 forms (principally in Dryopteris) which are 

 sterile and similarly intermediate between two 

 species. 



Some of these are very characteristic and 

 might be considered separate species. At 

 least two have been so described. This view, 

 however, is untenable because of their ster- 

 ility, and their distribution, rare or occasional 

 with the parent species, or at least in a local- 

 ity where these grow or have grown. That 

 they are mutations seems very doubtful, be- 

 cause the actual differences are so great, and 

 especially since in these differences they re- 

 semble the other reputed parent. For ex- 

 ample, sterile intermediates are known be- 

 tween Dryopteris marginalis and six other 

 species. Some resemble marginalis most, 

 some the other species, but all agree in pos- 

 sessing distinctive characters of each of two 

 species. For similar reasons, these forms can 

 not be satisfactorily explained on ecological 

 grounds. 



If it is objected that fern hybrids must, 

 because of the conditions required for the 

 transference of spermatozoids, be too rare to 

 account for these plants which are rather 

 common, it may be said that Dryopteris cris- 

 tata X marginalis, one of the authenticated 

 crosses, is the commonest of them all. It 

 may be expected in any swanipy woodland 

 where the parent species occur. This being the 

 case, we are bound to expect the other forms 

 to be found at least occasionally, and it seems 

 only logical to conclude that such intermediate 

 sterile forms as are analogous in general char- 

 acters to D. cristata X marginalis, belong in 

 the same category, and are likewise hybrids. 



