A. Gray—Memorial of George Engelmann. 65 
‘devoting himself to a particular genus or group of plants (gen- 
erally the more difficult) until he had elucidated it as com- 
pletely as lay within his power. In this way all his work was 
made to tell effectively. 
Thus his first monograph of the genus Cuscuta (published in 
this Journal in 1842), of which when Engelmann took it up we 
were supposed to have only one indigenous species, and that 
not peculiar to the United States, be immediately brought 
up to fourteen species without going west of the Mississippi 
valley. In the year 1859, after an investigation of t! 
whole genus in the materials scattered through the principal 
herbaria of Europe and this country, he published in the first 
volume of the St. Louis Academy of Sciences, a systematic 
arrangement of all the Cuscute, characterizing seventy-seven 
species, besides others classed as perhaps varieties. 
Mentioning here only monographical subjects, we should 
next refer to his investigations of the Cactus family, upon 
which his work was most extensive and important, as well as 
particularly difficult, and upon which Dr. Engelmann’s author- 
ity is of the very highest. He essentially for the first time 
established the arrangement of these plants upon floral and 
carpological characters. This formidable work was begun in 
his sketch of the botany of Dr. A. Wislizenus’s Expedition 
from Missouri to North Mexico, in the latter’s memoir of this 
tour, published by the United States Senate. It was followed 
up by his account (in this Journal, 1852), of the Giant Cactus 
on the Gila (Cereus giganteus) and an allied species; by his 
Synopsis of the Cactacese of the United States, published in the 
roceedings of the American Academy of Arts and Sciences, 
1856; and by his two illustrated memoirs upon the Southern 
and Western species, one contributed to the fourth volume of 
the series of Pacific Railroad Expedition Reports, the other to 
Emory’s Report on the Mexican Boundary Survey. He had 
made large preparations for a greatly needed revision of at least 
the North American Cactacee. But although his collections 
and sketches will be indispensable to the future monographer, 
very much knowledge of this difficult group of plants is lost by 
his death. 
_Upon-two other peculiarly American groups of plants, very 
difficult of elucidation in herbarium specimens, Yucca and 
Agave, Dr. Engelmann may be said to have brought his work | 
up to the time. Nothing of importance is yet to be added to 
what he modestly styles “Notes on the Genus Yucca,” pub- 
lished in the third volume of the Transactions of the St. Louis © 
Academy, 1873, and not much to the “Notes on Agave,” illus- 
_ trated by photographs, included in the same volume and pub- — 
_ lished in 1875. Pee : 
Am. Jour, So Vou. XXVIII. No. 163.—Juny, 1884. 
