rest of Europe and in the United States, 
however, I believe the spread has been 
in the opposite direction — from rail- 
road tracks to nearby fields and waste 
ground. This lateral spread, dependent 
on the relatively inefficient wind dis- 
persal of seeds, has not progressed very 
far in the United States, so that the spe- 
cies is still restricted to railroads and 
adjacent areas. My belief in this lateral 
spread received a temporary setback 
when I found a large colony growing in 
a patch of waste ground located more 
than eight miles from the nearest rail- 
road, a distance many orders of magni- 
tude greater than can be explained on 
the basis of wind dispersal. My faith 
was restored, however, when I consult- 
ed a topographic map and found that 
the New York, Ontario, and Western 
Railroad, which closed in 1957, used to 
pass through the middle of the area 
now occupied by the weed lot. 
Having established how dwarf snap- 
dragon spreads along railroad tracks, I 
then began to investigate how the plant 
manages to thrive in its apparently hos- 
tile environment. My first interest was 
in finding out how many of the newly 
germinated seedlings, which appear in 
large numbers in late spring, survive 
the stresses and disturbances of a rail- 
Passing trains may brush against dwarf 
snapdragon plants, above, dispersing 
seeds along the tracks. Wood sorrel, left, 
and other pastureland weeds are 
common where railroads and farm 
fields intersect. 
road long enough to set some seed and 
thus be represented in the next genera- 
tion. I followed the fate of a large num- 
ber of individually marked plants for 
four months, expecting that lack of suf- 
ficient water would be the chief cause of 
premature death, especially among the 
highly vulnerable young seedlings. 
What I found was completely unex- 
pected: the vast majority of deaths were 
the result, not of water shortage, but of 
herbivory. Sometimes just the tops of 
plants were nipped off or small bites 
were taken out of leaves; at other times, 
whole plants were eaten. Occasionally, 
all that remained of my carefully 
marked seedling was the loop of col- 
ored thread that I had tied around it, 
found lying on the cinders. I failed in 
my attempts to catch the culprits by 
baiting live traps with tender dwarf 
63 
