Prev | Current Page 166 | Next

Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"

The pollen-grains
from the short-styled flowers, though variable in size, are to those of the
long-styled, as far as I could make out, as 100 to 83 in their longer diameter.
Sethia obtusifolia is heterostyled like S. acuminata.
Cratoxylon formosum (Hypericineae).
Mr. Thiselton Dyer remarks that this tree, an inhabitant of Malacca and Borneo,
appears to be heterostyled. (3/21. 'Journal of Botany' London 1872 page 26.) He
sent me dried flowers, and the difference between the two forms is conspicuous.
In the short-styled form the pistils are in length to those of the short-styled
as 100 to 40, with their globular stigmas about twice as thick. These stand just
above the numerous anthers and a little beneath the tips of the petals. In the
short-styled form the anthers project high above the pistils, the stigmas of
which diverge between the three bundles of stamens, and stand only a little
above the tips of the sepals. The stamens in this form are to those of the long-
styled as 100 to 86 in length; and therefore they do not differ so much in
length as do the pistils. Ten pollen-grains from each form were measured, and
those from the short-styled were to those from the long-styled as 100 to 86 in
diameter. This plant, therefore, is in all respects a well-characterised
heterostyled species.
Aegiphila elata (Verbenaceae).


Pages:
154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178