BROOKLYN BOTANIC GARDEN 
LEAFLETS 
THE BROOKLYN INSTITUTE OF ARTS AND SCIENCES 
Series IV Brooklyn, N. Y., June 21, 1916. 
No. 8. 
FIELD TRIPS FOR THE STUDY OF 
VARIATION AND EVOLUTION 
The other day I saw a stretch of New England hillside three 
blocks long covered with a wild double-flowered form of the 
common Celandine ( Chelidonium majus). The adjacent hillsides 
for miles were scoured for other patches, but none but single- 
flowered plants were to be found. So I concluded this patch was 
the result of an isolated variation in form of a single plant which 
had chanced to occur in a favorable situation and spread till it 
numbered its peculiar kind by the thousands. 
Thus it is that many of our most striking forms of cultivated 
flowers, fruits and vegetables have arisen— simply chance varia- 
tions which fortunately have occurred in cultivated grounds and 
caught the eye of the men who tended them. For though these 
variations are found among wild as well as among cultivated 
plants, the wild variants seldom are fortunate enough to persist 
and spread, partly because many of these new forms differ from 
their immediate relatives by characters which are handicaps in 
their own unaided struggle for existence, though these handicaps 
are often what make them most prized by man. 
To mention a few cases with such handicaps, take the Cali- 
fornia navel orange, most double-flowering plants, and theyellow 
carnation. The navel orange originated about 1822 in Bahia, 
Brazil, as a branch bearing seedless oranges, on a tree, the other 
branches of which bore only oranges having seeds. The branch 
was discovered, and trees entirely navel orange bearing propa- 
gated from it by a Portuguese gardener. In 1870 it was intro- 
duced into the United States and a few years later into California, 
first at Riverside, where two of the original trees may still be 
seen. Left to itself, the navel orange variation would probably 
have disappeared in a few years by being overgrown by younger 
