--Diameter
of the pollen-grains, size of anthers and structure of stigma in the different
forms.--Affinities of the genera which include heterostyled species.--Nature of
the advantages derived from heterostylism.--The means by which plants became
heterostyled.--Transmission of form.--Equal-styled varieties of heterostyled
plants.--Final remarks.
CHAPTER VII.
POLYGAMOUS, DIOECIOUS, AND GYNO-DIOECIOUS PLANTS.
The conversion in various ways of hermaphrodite into dioecious plants.--
Heterostyled plants rendered dioecious.--Rubiaceae.--Verbenaceae.--Polygamous
and sub-dioecious plants.--Euonymus.--Fragaria.--The two sub-forms of both sexes
of Rhamnus and Epigaea.--Ilex.--Gyno-dioecious plants.--Thymus, difference in
fertility of the hermaphrodite and female individuals.--Satureia.--Manner in
which the two forms probably originated.--Scabiosa and other gyno-dioecious
plants.--Difference in the size of the corolla in the forms of polygamous,
dioecious, and gyno-dioecious plants.
CHAPTER VIII.
CLEISTOGAMIC FLOWERS.
General character of cleistogamic flowers.--List of the genera producing such
flowers, and their distribution in the vegetable series.--Viola, description of
the cleistogamic flowers in the several species; their fertility compared with
that of the perfect flowers.--Oxalis acetosella.--O.
Pages:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25