We found that the majority of ballistic seeds tested [N = 74 of 78 in Vicia
saliva ssp. nigra (Fabaceae); N = 25 of 27 in Croton capitatus var, capita
tus (Euphorbiaceae)] were projected at angles that would yield a greater di
stance than the average of seeds with the same initial speed projected at r
andom angles. In addition, the median of fractional distance error (maximum
distance - seed distance)/(maximum distance), of the seeds were 0.11 and 0
.04 for V. sativa and C. capitatus, respectively. Seed projection distance
was modeled by using initial projection angle, initial speed, and measured
drag, along with other seed data. We improved upon previous such studies by
using dual-angle high-speed stroboscopic photography to determine initial
projection angle and speed. We also measured seed drag in a low-turbulence
wind tunnel. Seed projection positions on the plant, which also affect seed
projection distance, were found to be primarily from the top of the plant,
with 98 of 137 and 407 of 407 fruits in the upper half of the plant for V.
sativa and C. capitatus, respectively. Our findings are significant becaus
e they suggest that in addition to the ballistic projection mechanism itsel
f. the species studied have additional adaptations that result in enhanced
seed projection distance from the parent plant.