The Different Forms of Flowers on Plants of the Same Species | Page 4

BY THE AUTHOR AS A SMALL
TRIBUTE OF RESPECT AND AFFECTION.

CONTENTS.
INTRODUCTION.
CHAPTER I.
HETEROSTYLED DIMORPHIC PLANTS: PRIMULACEAE.
Primula veris or the cowslip.--Differences in structure between the two
forms.-- Their degrees of fertility when legitimately and illegitimately
united.--P. elatior, vulgaris, Sinensis, auricula, etc.--Summary on the
fertility of the heterostyled species of Primula.--Homostyled species of

Primula.--Hottonia palustris.--Androsace vitalliana.
CHAPTER II.
HYBRID PRIMULAS.
The oxlip a hybrid naturally produced between Primula veris and
vulgaris.--The differences in structure and function between the two
parent-species.--Effects of crossing long-styled and short-styled oxlips
with one another and with the two forms of both
parent-species.--Character of the offspring from oxlips artificially
self-fertilised and cross-fertilised in a state of nature.--Primula elatior
shown to be a distinct species.--Hybrids between other heterostyled
species of Primula.--Supplementary note on spontaneously produced
hybrids in the genus Verbascum.
CHAPTER III.
HETEROSTYLED DIMORPHIC PLANTS--continued.
Linum grandiflorum, long-styled form utterly sterile with own-form
pollen.-- Linum perenne, torsion of the pistils in the long-styled form
alone.--Homostyled species of Linum.--Pulmonaria officinalis, singular
difference in self-fertility between the English and German long-styled
plants.--Pulmonaria angustifolia shown to be a distinct species,
long-styled form completely self-sterile.-- Polygonum
fagopyrum.--Various other heterostyled genera.--Rubiaceae.--Mitchella
repens, fertility of the flowers in pairs.--Houstonia.--Faramea,
remarkable difference in the pollen-grains of the two forms; torsion of
the stamens in the short-styled form alone; development not as yet
perfect.--The heterostyled structure in the several Rubiaceous genera
not due to descent in common.
CHAPTER IV.
HETEROSTYLED TRIMORPHIC PLANTS.

Lythrum salicaria.--Description of the three forms.--Their power and
complex manner of fertilising one another.--Eighteen different unions
possible.--Mid- styled form eminently feminine in nature.--Lythrum
Graefferi likewise trimorphic.--L. hymifolia dimorphic.--L.
hyssopifolia homostyled.--Nesaea verticillata
trimorphic.--Lagerstroemia, nature doubtful.--Oxalis, trimorphic
species of.--O. Valdiviana.--O. Regnelli, the illegitimate unions quite
barren.- -O. speciosa.--O. sensitiva.--Homostyled species of
Oxalis.--Pontederia, the one monocotyledonous genus known to
include heterostyled species.
CHAPTER V.
ILLEGITIMATE OFFSPRING OF HETEROSTYLED PLANTS.
Illegitimate offspring from all three forms of Lythrum salicaria.--Their
dwarfed stature and sterility, some utterly barren, some fertile.--Oxalis,
transmission of form to the legitimate and illegitimate
seedlings.--Primula Sinensis, illegitimate offspring in some degree
dwarfed and infertile.--Equal-styled varieties of P. Sinensis, auricula,
farinosa, and elatior.--P. vulgaris, red- flowered variety, illegitimate
seedlings sterile.--P. veris, illegitimate plants raised during several
successive generations, their dwarfed stature and
sterility.--Equal-styled varieties of P. veris.--Transmission of form by
Pulmonaria and Polygonum.--Concluding remarks.--Close parallelism
between illegitimate fertilisation and hybridism.
CHAPTER VI.
CONCLUDING REMARKS ON HETEROSTYLED PLANTS.
The essential character of heterostyled plants.--Summary of the
differences in fertility between legitimately and illegitimately fertilised
plants.--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. sensitiva, three forms of cleistogamic
flowers.--Vandellia.--Ononis.--Impatiens.--Drosera.--Miscellaneous
observations on various other cleistogamic plants.--Anemophilous
species producing cleistogamic flowers.--Leersia, perfect flowers rarely
developed.-- Summary and concluding remarks on the origin of
cleistogamic flowers.--The chief conclusions which may be drawn from
the observations in this volume.
INDEX.
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THE DIFFERENT FORMS OF FLOWERS ON PLANTS OF THE
SAME SPECIES.
INTRODUCTION.
The subject of the present volume, namely the differently formed
flowers normally produced by certain kinds of plants, either on the
same stock or on distinct stocks, ought to have been treated by a
professed botanist, to which distinction I can lay no claim. As far as the
sexual relations of flowers are concerned, Linnaeus long ago divided
them into hermaphrodite, monoecious, dioecious, and polygamous
species. This fundamental distinction, with the aid of several
subdivisions in each of the four classes, will serve my purpose; but the
classification is artificial, and the groups often pass into one another.
The hermaphrodite class contains two interesting sub-groups, namely,
heterostyled and cleistogamic plants; but there are several other less
important subdivisions, presently to be given, in which flowers
differing in various ways from one another are produced by the same
species.
Some plants were described by me several years ago, in a series of
papers read before the Linnean Society, the individuals of which exist
under two or three forms, differing in the length of their pistils and
stamens and in other respects. (Introduction/1. "On the Two Forms or
Dimorphic