The pollen-grains of the short-styled form are to those of the
long-styled as 100 to 82 in diameter. This plant is therefore without doubt
heterostyled.
I experimented only in an imperfect manner on the relative fertility of the two
forms. Short-styled flowers were dragged several times over two heads of flowers
on long-styled plants, protected under a net, which were thus legitimately,
though not fully, fertilised. They produced 22 seeds, or 11 per flower-head.
Three flower-heads on long-styled plants received pollen in the same manner from
other long-styled plants, and were thus illegitimately fertilised. They produced
14 seeds, or only 4.66 per flower-head.
Two flower-heads on short-styled plants received pollen in like manner from
long-styled flowers, and were thus legitimately fertilised. They produced 8
seeds, or 4 per flower-head.
Four heads on short-styled plants similarly received pollen from other short-
styled plants, and were thus illegitimately fertilised. They produced 9 seeds,
or 2.25 per flower-head.
The results from fertilising the flower-heads in the above imperfect manner
cannot be fully trusted; but I may state that the four legitimately fertilised
flower-heads yielded on an average 7.50 seeds per head; whereas the seven
illegitimately fertilised heads yielded less than half the number, or on an
average only 3.
Pages:
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162