36 SILVA OF NORTH AMERICA. 
LEGUMINOS. 
Dalea spinosa was first gathered by Fremont in 1849, but his specimen showed neither flowers 
nor fruit, and the species was first described from the specimens collected in 1852 on the Colorado 
Desert by Dr. George Thurber,’ the botanist of the United States and Mexican Boundary Survey 
Commission. 
1 George Thurber (1821-1890) was born in Providence, Rhode 
Island, where he was educated and for several years practiced his 
profession of apothecary. Through the influence of Dr. John 
Torrey he was appointed in 1850 botanist to the United States 
Commission to establish the boundary line between our territory 
and that of Mexico ; and to his scientific duties in connection with 
the survey were added those of quartermaster and commissary. 
Dr. Thurber devoted five years to exploring the natural resources 
of the boundary region from the shores of the Gulf of Mexico to 
those of the Pacific Ocean, discovering many interesting plants, 
including a few trees. The most important of these discoveries 
were described by Professor Asa Gray in the Memoirs of the 
American Academy (Plante Thurberiane). Thurber, on the com- 
pletion of his duties in connection with the survey, settled in New 
York, where he was employed in the United States Assay Office, 
and later became a lecturer before the Cooper Union and in the 
New York College of Pharmacy. In 1859 he was appointed pro- 
fessor of botany and horticulture in the Agricultural College of 
Michigan, retaining his chair until 1863, when he became editor 
of the American Agriculturist, a position which he held until 
within a short time of his death. He was a most accomplished 
and successful writer on all matters pertaining to horticulture and 
related subjects, and exerted a wide and always wholesome influ- 
ence through his own writings and through the improvement which 
his editorial example produced in the character and scope of the 
agricultural and horticultural journals of the United States. A 
Malvaceous plant of the Mexican boundary, named by Gray Thur- 
beria in honor of the discoverer, is now referred to Gossypium, but 
Thurberia, a genus of American grasses, plants to which he devoted 
years of study, and which he knew better than any of his con- 
temporaries, keeps green the memory of a learned and interesting 
man. 
EXPLANATION OF THE PLATE. 
PLate CXL. 
. Diagram of a flower. 
A flower, enlarged. 
naowiP Od 
oa 
bh 
So 
. A fruit, enlarged. 
An ovule, much magnified. 
DALEA SPINOSA. 
. A flowering branch, natural size. 
. Portion of a seedling plant showing serrate leaves, natural size. 
. The petals of a flower, displayed, enlarged. 
- Vertical section of a flower, the corolla removed, enlarged. 
. Vertical section of an ovary, enlarged. 
A fruiting branch, natural size. 
11. Vertical section of a fruit, enlarged. 
12. A seed, enlarged. 
13. Vertical section of a seed, enlarged. 
14, An embryo, much magnified. 
