September 26, 1884.] 



SCIENCE, 



309 



of the old ' Flora,' and is therefore in a certain 

 sense a new edition of that work, although 

 entirely recast and rewritten. 



The present volume is of special importance 

 and value. Its publication has long, been 

 looked for with impatience, and its pages will 

 be examined with the deepest interest b} T all 

 students of American botairy. It contains the 

 mature views of the most acute and profound 

 student of the great and difficult order of 

 Compositae, to which not less than one-eighth 

 of all the flowering plants of North America 

 must be referred, — an order, as represented 

 on this continent, to the comprehension of 

 which he has given his best efforts and un- 

 flagging industry for more than half a century, 

 and which, it is safe to predict, no other bota- 

 nist would ever have been able to so elucidate. 

 The plants, belonging to 5 families, 274 genera, 

 and 1,767 species, are characterized in this 

 volume, which contains, exclusive of its very 

 full index, 446 pages, of which all but about 

 50 are devoted to Compositae, with 237 genera 

 and 1,610 species. 



A brief and necessaril} T imperfect comparison 

 of the families here elaborated, as represented 

 in this country at the present time, with what 

 was known of them when the* second volume 

 of Torre> and Gray's ' Flora ' appeared, be- 

 tween 1841 and 1843, will show the extent and 

 character of the work which has occupied 

 Professor Gray of late years, and the impor- 

 tance of the service which he has performed, 

 as well as the zeal and industry of the botanical 

 travellers and explorers who have long been 

 busy, under his general direction, in all parts 

 of the eountiy. 



Adoxa, transferred from Araliaceae, now 

 appears, represented b}- its single widely dis- 

 tributed species, among Caprifoliaceae. Ad- 

 ditions to Sambucus are S. melanocarpa (of 

 the northern Rocky Mountains) and S. Mexi- 

 cana (a Mexican species of the boundary and 

 of southern California). The Texas station, 

 near San Antonio, of this tree, is not given. 

 In Viburnum, V. densiflorum — a southern 

 species, as Professor Gray remarks, too near 

 V. aurifolium — is admitted. Symphoricarpus, 

 a North- American genus, is increased by a new, 

 long-flowered section with three species, of the 

 south-western mountains : Lonicera conjugialis 

 of the Sierra forests of California, and L. 

 Utahensis of the northern Rocky Mountains 

 and Utah, are additions to that genus which 

 shows besides mairy important changes in the 

 rank and position of various species. Impor- 

 tant changes appear in Rubiaceae. Loganieae, 

 which appeared in the old ' Flora ' as a tribe 



of this order, is now placed as a famih T be- 

 tween Asclepiadaceae and Gentianaceae, in 

 the preceding volume. Borreria is reduced to 

 Spermacoce ; and Hedyotis is split up among 

 Houstonia, Oldenlandia, and Pentodon. Be- 

 sides these changes, eight genera not in the 

 old ' Flora ' are represented b\ r plants, mostly 

 of West-Indian or Mexican origin, which recent 

 explorations have brought to light in southern 

 Florida and along the Mexican boundar}'. 

 Kelloggia, a monotypical genus of the Pacific 

 slope, commemorates the botanical labors and 

 zeal of Dr. Albert Kellogg, one of the early 

 explorers of California botany. The large 

 genus Galium is increased from eighteen to 

 thirty-seven species. 



In Valerianaceae, Plectritis and Fedia are 

 merged in Valerianella, while the species of 

 Valeriana are increased from six to eight. 



The extension and changes in Compositae 

 during the last forty years, as was to have been 

 expected in a family so largely represented in 

 our flora, and of such wide and general distri- 

 bution, far exceed, in number and importance, 

 the changes in the smaller orders alluded to 

 above. 



This order, as represented in North America 

 at the time of the publication of the old 

 'Flora,' was grouped in eight tribes: in the 

 new elaboration, representatives of eleven 

 tribes appear. It now contains representatives 

 of 237 genera and 1,610 species; while fort}' 

 years ago there were, within the limits of the 

 region embraced by Torrey and Graj-'s publi- 

 cation, only 199 genera and 1,011 species. Of 

 the large genera, Aster, which Dr. Gray re- 

 marks " is far the most difficult of our genera, 

 both from the settlement of the names of the 

 species and from their limitation, in respect to 

 which little satisfaction has been obtained as 

 the result of long and repeated studies," heads 

 the list with 124 species, ■ — seven less than the 

 author's elaboration of this genus for the old 

 •Flora.' 



This diminution of species is due to the fact 

 that several of the Linnaean species have been 

 dropped, from one cause or another, and be- 

 cause Aster, largely a genus of eastern America, 

 has not received many additions through west- 

 ern explorations. The same remarks are true, 

 too, of Solidago, our second largest genus of 

 Compositae, now represented in our flora hy 

 74 species, although not less than 94 were 

 admitted in the old 'Flora.' Some species 

 have been dropped entirely, and others reduced 

 to varieties ; while few new additions to the 

 genus have been made. Erigeron, on the con- 

 trary, has been nearly doubled, increasing from 



