BOTANICAL GAZETTE. 101 



Aster Tradescanti and A.^miser. — lu response lo a query in u recent Gazette, 

 wc have I'eceived the following.- 



A. Tradescniiti is distinguished from A. »i,uer by its greater smoothness; by the 

 more deflnitel}' racemed inflorescence; and by the less marked serration of the middle 

 of the more slender leaves; in var. frffgilis the margin is entire. Both species are 

 perplexingly variable, but, in my judgment, they may be clearly determined by the 

 above points. — M. B. F. 



A Valuable Fern Catalogue. — Mr. Geo. E. Davenport has in preparation, and 

 nearly ready for printing, a Catalogue of the N. A. Ferns (north of Mexico) in the 

 Davenport Herb., Mass. Hort. Soc, with notes giving localities, time of collection, 

 names of collectors and donors, with occasional critical remarks, which lie will pub 

 lish provided he can obtain subscribers enough to enable him to do so. It will proba- 

 bly make a neat pamphlet of some twenty pages, and be a comi»lete and accurate cata- 

 logue of N. A. P^'erns based on actual specimens, with an appendix giving a list of all 

 the doubtful species. The price will, of course, depend uj)on llie number of subscri- 

 bers, but probably in no case will it exceed 50 cents per copy. Subscriptions may be 

 .sent direct to Mr. Davenport's address at Boston, Mass. 



The Law Governing Sex. — Mr. Thomas Meehan referied lo his observations 

 originally reported to the Academ}% developing an entirely new view of the laws of 

 sex from that tormerly prevailing, and which proved that what we called the female 

 sex or final reproductive element in flowers, required a higher grade of nutritive 

 power to perfect than_the male Though numberless facts have proved this point, 

 there have always been some which, though tliej^ have off'ered no obstahle, have at 

 least not been capable of explanation b}' the light of this theoiy, and among these 

 have been some connected with dia-cious plants. Among hermaphrodite and especi- 

 ally among monoecious plants there has been no diflHculty in tracing the operation of 

 this principle. In such coniferous trees as pines, flrs, and larciies, there is no diffi- 

 cult}^ in perceiving that branches once bearing female flowers, and maturing cones and 

 seeds, produce nothing but male flowers when the branches come in time to be weak- 

 ened by the shade of younger branches, or in some other way are .imperfectly nour- 

 ished. But when we come to the red cedar, Junipervfi Virginiana,, ^'herc coua trees 

 are always wholly male, and others always seed-bearing, no difi'erence could be found 

 in the vigor of the trees. As in the mona^cious cases we found the female element in 

 exact proportion to nutritious advantages, we looked for the seed-licaring trees of the 

 red cedar to be more vigorous than the males, but found instead all equally vigorous 

 and healthj\ 



The enormous crop of seed borne by the silver maiile this year, together with the 

 confirmation of their truly dia-cious charactei', have not only furnished an ex])l:ination 

 of the apparent anomaly, but at the same time affords one of the best possible illus- 

 trations of the new theory. 



As already noted in communications to the Academy, the flowers in Acer rubnun and 

 Acer dasi/carpum are alike in all trees when the petals first open. The anthers seem 

 perfectly formed when another stage of growth commences. The pistils elongate in 

 the female flowers while the filaments remain stationaiy, and the anthers never open; 

 while in the male flowers the pistils do not grow, but the filaments elongate, and the 

 anthers" are carried on to perfection. Each tree is in fact strictly a male or a female 

 tree. 



It is a matter within common knowledge that after the maturity of the immense 

 crop of seeds last month, the bearing trees were comparatively leafless, while the 

 completely barren male trees abounded with foilage. There is a well-known morpho- 



