Bios 
Rise of the Angiosperms 
Among the pollen tubes of flowering plants, the race is to 
the swift and may help explain the angiosperms' success 
by David L. Mulcahy 
About 125 million years ago, the 
earth’s terrestrial vegetation underwent 
a dramatic change. At that time, a 
newly evolved and highly competitive 
group of plants suddenly rose to domi- 
nance. These were the angiosperms, or 
flowering plants, and they relegated the 
gymnosperms (most familiar to us as 
conifers, but also including cycads and 
the ginkgo) and the ferns to a secondary 
position. The change was swift, at least 
in terms of geologic time and, to this 
day, irreversible. Angiosperms now oc- 
cupy well over 90 percent of the earth’s 
vegetated surface and, aside from some 
harvest of marine algae, constitute vir- 
tually 100 percent of our agricultural 
species. 
Where did they come from, what 
were their ancestors, and most intrigu- 
ing of all, why were the angiosperms 
able to displace the gymnosperms and 
the ferns from their position of domi- 
nance? We have answers to some of 
these questions, but to a considerable 
extent, the rise of the angiosperms re- 
mains for modern botanists, as it was 
for Darwin, an “abominable mystery.” 
Today, in part because flowering plants 
represent the best hope for increasing 
agricultural yields and for utilizing the 
36 percent of the land surface that is too 
dry, toxic, or saline to support present 
crop species, it is more necessary than 
ever to understand this fascinating 
group of plants. 
On which points are present-day sci- 
entists closer to answers than were the 
Victorians? Thanks to Daniel Axelrod 
Germinating pollen grain of tomato David L Mulcahy 
30 
