branching plants for the purpose of fully and uniformly occupying afield, and
maximally utilizing solar irradiation. For many crops, farmers and plant breeders
have selected seed-bearing crops that mature most of their seeds more or less
simultaneously, to minimize harvest loss. It appears that such selection is occurring
for oilseed hemp. By contrast, wildC. sativaplants mature seeds sequentially over
a long season.
Fig. 1.5 Oilseed hemp.aField profile of a tall biotype grown at low density for seed production.
This illustrates traditional production of seeds employing well-spaced plants, which become quite
branched and produce manyflowers and seeds. However, harvest of the seeds from widespread
locations on the plant is difficult, and the plant has diverted much of its energy into production of
stems.bField profile of a short biotype with a dense, compact infructescence, grown at high
density for seed production. By comparison with (a), the concentration of seeds facilitates their
harvest, and minimizing stem production diverts most of the plant’s energy into seed development.
cA compact, elongated infructescence, ideal for seed harvest.dMature seeds (achenes)
20 E. Small