196. Flowers are for the production of seed (16). Stems and branches,
which for a time put forth leaves for vegetation, may at length put
forth flowers for reproduction.
Sec. 1. POSITION AND ARRANGEMENT OF FLOWERS, OR INFLORESCENCE.
197. Flower-buds appear just where leaf-buds appear; that is, they are
either _terminal_ or _axillary_ (47-49). Morphologically, flowers answer
to shoots or branches, and their parts to leaves.
198. In the same species the flowers are usually from axillary buds
only, or from terminal buds only; but in some they are both axillary and
terminal.
199. =Inflorescence=, which is the name used by Linnaeus to signify mode
of flower-arrangement, is accordingly of three classes: namely,
_Indeterminate_, when the flowers are in the axils of leaves, that is,
are from axillary buds; _Determinate_, when they are from terminal buds,
and so _terminate_ a stem or branch; and _Mixed_, when these two are
combined.
200. =Indeterminate Inflorescence= (likewise, and for the same reason,
called _indefinite inflorescence_) is so named because, as the flowers
all come from axillary buds, the terminal bud may keep on growing and
prolong the stem indefinitely. This is so in Moneywort (Fig. 199).
[Illustration: Fig. 199. Piece of a flowering-stem of Moneywort
(Lysimachia nummularia,) with single flowers successively produced in
the axils of the leaves, from below upwards, as the stem grows on.]
201. When flowers thus arise singly from the axils of ordinary leaves,
they are _axillary_ and _solitary_, not collected into flower-clusters.
202. But when several or many flowers are produced near each other, the
accompanying leaves are apt to be of smaller size, or of different shape
or character: then they are called BRACTS, and the flowers thus brought
together form a cluster. The kinds of flower-clusters of the
indeterminate class have received distinct names, according to their
form and disposition. They are principally _Raceme_, _Corymb_, _Umbel_,
_Spike_, _Head_, _Spadix_, _Catkin_, and _Panicle_.
203. In defining these it will be necessary to use some of the following
terms of descriptive botany which relate to inflorescence. If a flower
is stalkless, i. e. sits directly in the axil or other support, it is
said to be _sessile_. If raised on a naked stalk of its own (as in Fig.
199) it is _pedunculate_, and the stalk is a PEDUNCLE.
204. A peduncle on which a flower-cluster is raised is a _Common
peduncle_. That which supports each separate flower of the cluster is a
_Partial peduncle_, and is generally called a PEDICEL. The portion of
the general stalk along which flowers are disposed is called the _Axis
of inflorescence_, or, when covered with sessile flowers, the _Rhachis_
(back-bone), and sometimes the _Receptacle_. The leaves of a
flower-cluster generally are termed BRACTS. But when bracts of different
orders are to be distinguished, those on the common peduncle or axis,
and which have a flower in their axil, keep the name of _bracts_; and
those on the pedicels or partial flower-stalks, if any, that of
BRACTLETS or _Bracteoles_. The former is the preferable English name.
[Illustration: Fig. 200. A raceme, with a general peduncle (_p_),
pedicels (_p'_), bracts (_b_), and bractlets (_b'_). Plainly the bracts
here answer to the leaves in Fig. 199.]
205. =A Raceme= (Fig. 200) is that form of flower-cluster in which the
flowers, each on their own foot-stalk or pedicel, are arranged along the
sides of a common stalk or axis of inflorescence; as in the Lily of the
Valley, Currant, Barberry, one section of Cherry, etc. Each flower comes
from the axil of a small leaf, or bract, which, however, is often so
small that it might escape notice, and even sometimes (as in the Mustard
Family) disappears altogether. The lowest blossoms of a raceme are of
course the oldest, and therefore open first, and the order of blossoming
is _ascending_ from the bottom to the top. The summit, never being
stopped by a terminal flower, may go on to grow, and often does so (as
in the common Shepherd's Purse), producing lateral flowers one after
another for many weeks.
[Illustration: Fig. 201. A raceme. 202. A corymb. 203. An umbel.]
206. =A Corymb= (Fig. 202) is the same as a raceme, except that it is
flat and broad, either convex, or level-topped. That is, a raceme
becomes a corymb by lengthening the lower pedicels while the uppermost
remain shorter. The axis of a corymb is short in proportion to the lower
pedicels. By extreme shortening of the axis the corymb may be converted
into
207. =An Umbel= (Fig. 203) as in the Milkweed, a sort of flower-cluster
where the pedicels all spring apparently from the same point, from the
top of the peduncle, so as to resemble, when spreading, the rays of an
umbrella; whence the name. Here the pedicels are sometimes called the
_Rays_ of the umbel. And the bracts, when brought in this way into a
cluster or circle, form what is called an INVOLUCRE.
208. The corymb and the umbel being more or less level-topped, bringing
the flowers into a horizontal plane or a convex form, the ascending
order of development appears as _Centripetal_. That is, the flowering
proceeds from the margin or circumference regularly towards the centre;
the lower flowers of the former answering to the outer ones of the
latter.
209. In these three kinds of flower-clusters, the flowers are raised on
conspicuous _pedicels_ (204) or stalks of their own. The shortening of
these pedicels, so as to render the flowers _sessile_ or nearly so,
converts a raceme into a _Spike_, and a corymb or an umbel into a
_Head_.
210. =A Spike= is a flower cluster with a more or less lengthened axis,
along which the flowers are sessile or nearly so; as in the Plantain
(Fig. 204).
[Illustration: Fig. 204. Spike of the common Plantain or Ribwort.]
211. =A Head= (_Capitulum_) is a round or roundish cluster of flowers,
which are sessile on a very short axis or receptacle, as in the
Button-ball, Button-bush (Fig. 205), and Red Clover. It is just what a
spike would become if its axis were shortened; or an umbel, if its
pedicels were all shortened until the flowers became sessile. The head
of the Button-bush is naked; but that of the Thistle, of the Dandelion,
and the like, is surrounded by empty bracts, which form an _Involucre_.
Two particular forms of the spike and the head have received particular
names, namely, the _Spadix_ and the _Catkin_.
[Illustration: Fig. 205. Head of the Button-bush (Cephalanthus).]
212. =A Spadix= is a fleshy spike or head, with small and often
imperfect flowers, as in the Calla, Indian Turnip, (Fig. 206), Sweet
Flag, etc. It is commonly surrounded or embraced by a peculiar
enveloping leaf, called a SPATHE.
[Illustration: Fig. 206. Spadix and spathe of the Indian Turnip; the
latter cut through below.]
213. =A Catkin, or Ament=, is the name given to the scaly sort of spike
of the Birch (Fig. 207) and Alder, the Willow and Poplar, and one sort
of flower-clusters of the Oak, Hickory, and the like,--the so-called
_Amentaceous_ trees.
[Illustration: Fig. 207. Catkin, or Ament, of Birch.]
214. _Compound_ flower-clusters of these kinds are not uncommon. When
the stalks which in the simple umbel are the pedicels of single flowers
themselves branch into an umbel, a _Compound Umbel_ is formed. This is
the inflorescence of Caraway (Fig. 208), Parsnip, and almost all of the
great family of Umbelliferous (umbel-bearing) plants.
[Illustration: Fig. 208. Compound Umbel of Caraway.]
215. The secondary or partial umbels of a compound umbel are UMBELLETS.
When the umbellets are subtended by an involucre, this secondary
involucre is called an INVOLUCEL.
216. A _Compound raceme_ is a cluster of racemes racemosely arranged, as
in Smilacina racemosa. A _compound corymb_ is a corymb some branches of
which branch again in the same way, as in Mountain Ash. A _compound
spike_ is a spicately disposed cluster of spikes.
[Illustration: Fig. 209. Diagram of a simple panicle.]
217. =A Panicle=, such as that of Oats and many Grasses, is a compound
flower-cluster of a more or less open sort which branches with apparent
irregularity, neither into corymbs nor racemes. Fig. 209 represents the
simplest panicle. It is, as it were, a raceme of which some of the
pedicels have branched so as to bear a few flowers on pedicels of their
own, while others remain simple. A _compound panicle_ is one that
branches in this way again and again.
[Illustration: Fig. 210. Diagram of an opposite-leaved plant, with a
single terminal flower. 211. Same, with a cyme of three flowers; _a_,
the first flower, of the main axis; _b b_, those of branches. 212. Same,
with flowers also of the third order, _c c_.]
218. =Determinate Inflorescence= is that in which the flowers are from
terminal buds. The simplest case is that of a solitary terminal flower,
as in Fig. 210. This stops the growth of the stem; for its terminal bud,
becoming a blossom, can no more lengthen in the manner of a leaf-bud.
Any further growth must be from axillary buds developing into branches.
If such branches are leafy shoots, at length terminated by single
blossoms, the inflorescence still consists of solitary flowers at the
summit of stem and branches. But if the flowering branches bear only
bracts in place of ordinary leaves, the result is the kind of
flower-cluster called
219. =A Cyme.= This is commonly a flat-topped or convex flower-cluster,
like a corymb, only the blossoms are from terminal buds. Fig. 211
illustrates the simplest cyme in a plant with opposite leaves, namely,
with three flowers. The middle flower, _a_, terminates the stem; the two
others, _b b_, terminate branches, one from the axil of each of the
uppermost leaves; and being later than the middle one, the flowering
proceeds from the centre outwards, or is _Centrifugal_. This is the
opposite of the indeterminate mode, or that where all the flower-buds
are axillary. If flowering branches appear from the axils below, the
lower ones are the later, so that the order of blossoming continues
_centrifugal_ or, which is the same thing, _descending_, as in Fig. 213,
making a sort of reversed raceme or _false raceme_,--a kind of cluster
which is to the true raceme just what the flat cyme is to the corymb.
[Illustration: Fig. 213. Diagram of a simple cyme in which the axis
lengthens, so as to take the form of a raceme.]
220. Wherever there are bracts or leaves, buds may be produced from
their axils and appear as flowers. Fig. 212 represents the case where
the branches, _b b_, of Fig. 211, each with a pair of small leaves or
bracts about their middle, have branched again, and produced the
branchlets and flowers _c c_, on each side. It is the continued
repetition of this which forms the full or compound cyme, such as that
of the Laurestinus, Hobble-bush, Dogwood, and Hydrangea (Fig. 214).
[Illustration: Fig. 214. Compound cyme of Hydrangea arborescens, with
neutral enlarged flowers round the circumference.]
221. =A Fascicle= (meaning a bundle), like that of the Sweet William and
Lychnis of the gardens, is only a cyme with the flowers much crowded.
222. =A Glomerule= is a cyme still more compacted, so as to imitate a
head. It may be known from a true head by the flowers not expanding
centripetally, that is, not from the circumference towards the centre.
223. The illustrations of determinate or _cymose_ inflorescence have
been taken from plants with opposite leaves, which give rise to the most
regular cymes. But the Rose, Cinquefoil, Buttercup, etc., with alternate
leaves, furnish also good examples of cymose inflorescence.
224. =A Cymule= (or diminutive cyme) is either a reduced small cyme of
few flowers, or a branch of a compound cyme, i. e. a partial cyme.
225. =Scorpioid= or =Helicoid Cymes=, of various sorts, are forms of
determinate inflorescence (often puzzling to the student) in which one
half of the ramification fails to appear. So that they may be called
_incomplete cymes_. The commoner forms may be understood by comparing a
complete cyme, like that of Fig. 215 with Fig. 216, the diagram of a
cyme of an opposite-leaved plant, having a series of terminal flowers
and the axis continued by the development of a branch in the axil of
only one of the leaves at each node. The dotted lines on the left
indicate the place of the wanting branches, which if present would
convert this _scorpioid cyme_ into the complete one of Fig. 215. Fig.
217 is a diagram of similar inflorescence with alternate leaves. Both
are kinds of _false racemes_ (219). When the bracts are also wanting in
such cases, as in many Borragineous plants, the true nature of the
inflorescence is very much disguised.
[Illustration: Fig. 215. A complete forking cyme of an Arenaria, or
Chickweed.]
[Illustration: Fig. 216. Diagram of a scorpioid cyme, with opposite
leaves or bracts.]
[Illustration: Fig. 217. Diagram of analogous scorpioid cyme, with
alternate leaves or bracts.]
226. These distinctions between determinate and indeterminate
inflorescence, between corymbs and cymes, and between the true and the
false raceme and spike, were not recognized by botanists much more than
half a century ago, and even now are not always attended to in
descriptions. It is still usual and convenient to describe rounded or
flat-topped and open ramification as _corymbose_, even when essentially
cymose; also to call the reversed or false racemes or spikes by these
(strictly incorrect) names.
227. =Mixed Inflorescence= is that in which the two plans are mixed or
combined in compound clusters. A _mixed panicle_ is one in which, while
the primary ramification is of the indeterminate order, the secondary or
ultimate is wholly or partly of the determinate order. A contracted or
elongated inflorescence of this sort is called a THYRSUS. Lilac and
Horse-chestnut afford common examples of mixed inflorescence of this
sort. When loose and open such flower-clusters are called by the general
name of _Panicles_. The heads of Compositae are centripetal; but the
branches or peduncles which bear the heads are usually of centrifugal
order.
Sec. 2. PARTS OR ORGANS OF THE FLOWER.
228. These were simply indicated in Section II. 16. Some parts are
necessary to seed-bearing; these are _Essential Organs_, namely, the
_Stamens_ and _Pistils_. Others serve for protection or for attraction,
often for both. Such are the leaves of the Flower, or the _Floral
Envelopes_.
229. =The Floral Envelopes=, taken together, are sometimes called the
PERIANTH, also _Perigone_, in Latin form _Perigonium_. In a flower which
possesses its full number of organs, the floral envelopes are of two
kinds, namely, an outer circle, the CALYX, and an inner, the COROLLA.
230. =The Calyx= is commonly a circle of green or greenish leaves, but
not always. It may be the most brightly colored part of the blossom.
Each calyx-leaf or piece is called a SEPAL.
231. =The Corolla= is the inner circle of floral envelopes or
flower-leaves, usually of delicate texture and _colored_, that is, of
some other color than green. Each corolla-leaf is called a PETAL.
232. There are flowers in abundance which consist wholly of floral
envelopes. Such are the so-called full _double flowers_, of which the
choicer roses and camellias of the cultivator are familiar examples. In
them, under the gardener's care and selection, petals have taken the
place of both stamens and pistils. These are monstrous or unnatural
flowers, incapable of producing seed, and subservient only to human
gratification. Their common name of _double_ flowers is not a sensible
one: except that it is fixed by custom, it were better to translate
their Latin name, _flores pleni_, and call them _full flowers_, meaning
full of leaves.
233. Moreover, certain plants regularly produce _neutral flowers_,
consisting of floral envelopes only. In Fig. 214, some are seen around
the margin of the cyme in Hydrangea. They are likewise familiar in the
Hobble-bush and in Wild-Cranberry tree, Viburnum Oxycoccus; where they
form an attractive setting to the cluster of small and comparatively
inconspicuous perfect flowers which they adorn. In the Guelder Rose, or
Snow-ball of ornamental cultivation, all or most of the blossoms of this
same shrub are transformed into neutral flowers.
[Illustration: Fig. 218. A _flos plenus_, namely, a full double flower
of Rose.]
234. =The Essential Organs= are likewise of two kinds, placed one above
or within the other; namely, first, the STAMENS or fertilizing organs,
and second, the PISTILS, which are to be fertilized and bear the seeds.
[Illustration: Fig. 219. A stamen: _a_, filament; _b_, anther,
discharging pollen.]
[Illustration: Fig. 220. A pistil; with ovary, _a_, half cut away, to
show the contained ovules; _b_, style; _c_, stigma.]
235. =A Stamen= consists of two parts, namely, the FILAMENT or stalk
(Fig. 219 _a_), and the ANTHER (_b_). The latter is the only essential
part. It is a case, commonly with two lobes or cells, each opening
lengthwise by a slit, at the proper time, and discharging a powder or
dust-like substance, usually of a yellow color. This powder is the
POLLEN, or fertilizing matter, to produce which is the office of the
stamen.
236. =A Pistil= (Fig. 220, 221) when complete, has three parts; OVARY,
STYLE, and STIGMA. The _Ovary_, at base, is the hollow portion, which
contains one or more OVULES or rudimentary seeds. The _Style_ is the
tapering portion above: the _Stigma_ is a portion of the style, usually
its tip, with moist naked surface, upon which grains of pollen may lodge
and adhere, and thence make a growth which extends down to the ovules.
When there is no style then the stigma occupies the tip of the ovary.
[Illustration: Fig. 221. Model of a simple pistil, with ovary cut across
and slightly opened ventrally, to show the ovules and their attachment.]
237. =The Torus= or =Receptacle= is the end of the flower-stalk, or the
portion of axis or stem out of which the several organs of the flower
grow, upon which they are borne (Fig. 223).
[Illustration: Fig. 222. Flower of Sedum ternatum, a Stonecrop.]
[Illustration: Fig. 223. Parts of same, two of each kind, separated and
displayed; the torus or receptacle in the centre; _a_, a sepal; _b_, a
petal; _c_, a stamen; _d_, a pistil.]
238. The parts of the flower are thus disposed on the receptacle or axis
essentially as are leaves upon a very short stem; first the sepals, or
outer floral leaves; then the petals or inner floral leaves; then the
stamens; lastly, at summit or centre, the pistils, when there are two or
more of them, or the single pistil, when only one. Fig. 223 shows the
organs displayed, two of each kind, of such a simple and symmetrical
flower as that of a Sedum or Stonecrop, Fig. 222.
Sec. 3. PLAN OF FLOWER.
239. All flowers are formed upon one general plan, but with almost
infinite variations, and many disguises. This common plan is best
understood by taking for a type, or standard for comparison, some
_perfect_, _complete_, _regular_, and _symmetrical_ blossom, and one as
simple as such a blossom could well be. Flowers are said to be
_Perfect_ (_hermaphrodite_), when provided with both kinds of essential
organs, i. e. with both stamens and pistils.
_Complete_, when, besides, they have the two sets of floral envelopes,
namely, calyx and corolla. Such are completely furnished with all that
belongs to a flower.
_Regular_, when all the parts of each set are alike in shape and size.
_Symmetrical_, when there is an equal number of parts in each set or
circle of organs.
240. Flax-flowers were taken for a pattern in Section II. 16. But in
them the five pistils have their ovaries as it were consolidated into
one body. Sedum, Fig. 222, has the pistils and all the other parts free
from such combination. The flower is perfect, complete, regular, and
symmetrical, but is not quite as simple as it might be; for there are
twice as many stamens as there are of the other organs. Crassula, a
relative of Sedum, cultivated in the conservatories for winter
blossoming (Fig. 224) is simpler, being _isostemonous_, or with just as
many stamens as petals or sepals, while Sedum is _diplostemonous_,
having double that number: it has, indeed, two sets of stamens.
[Illustration: Fig. 224. Flower of a Crassula. 225. Diagram or
ground-plan of same.]
241. =Numerical Plan.= A certain number either runs through the flower
or is discernible in some of its parts. This number is most commonly
either five or three, not very rarely four, occasionally two. Thus the
_ground-plan_ of the flowers thus far used for illustration is five.
That of Trillium (Fig. 226, 227) is three, as it likewise is as really,
if not as plainly, in Tulips and Lilies, Crocus, Iris, and all that
class of blossoms. In some Sedums all the flowers are in fours. In
others the first flowers are on the plan of five, the rest mostly on the
plan of four, that is, with four sepals, four petals, eight stamens (i.
e. twice four), and four pistils. Whatever the ground number may be, it
runs through the whole in symmetrical blossoms.
[Illustration: Fig. 226. Flower of a Trillium; its parts in threes.]
[Illustration: Fig. 227. Diagram of flower of Trillium. In this, as in
all such diagrams of cross-section of blossoms, the parts of the outer
circle represent the calyx; the next, corolla; within, stamens (here in
two circles of three each, and the cross-section is through the
anthers); in the centre, section of three ovaries joined into a compound
one of three cells.]
242. =Alternation of the successive Circles.= In these flowers the parts
of the successive circles _alternate_; and such is the rule. That is,
the petals stand over the intervals between the sepals; the stamens,
when of the same number, stand over the intervals between the petals; or
when twice as many, as in the Trillium, the outer set alternates with
the petals, and the inner set, alternating with the other, of course
stands before the petals; and the pistils alternate with these. This is
just as it should be on the theory that the circles of the blossom
answer to whorls of leaves, which alternate in this way. While in such
flowers the circles are to be regarded as whorls, in others they are
rather to be regarded as condensed spirals of alternate leaves. But,
however this may be, in the mind of a morphological botanist,
243. =Flowers are altered Branches=, and their parts, therefore, altered
leaves. That is, certain buds, which might have grown and lengthened
into a leafy branch, do, under other circumstances and to accomplish
other purposes, develop into blossoms. In these the axis remains short,
nearly as it is in the bud; the leaves therefore remain close together
in sets or circles; the outer ones, those of the calyx, generally
partake more or less of the character of foliage; the next set are more
delicate, and form the corolla, while the rest, the stamens and pistils,
appear under forms very different from those of ordinary leaves, and are
concerned in the production of seed. This view gives to Botany an
interest which one who merely notices the shape and counts the parts of
blossoms, without understanding their plan, has no conception of.
244. That flowers answer to branches may be shown, first, from their
position. As explained in the section on Inflorescence, flowers arise
from the same places as branches, and from no other; flower-buds, like
leaf-buds, appear either on the summit of a stem, that is, as a terminal
bud, or in the axil of a leaf, as an axillary bud. And, as the plan of a
symmetrical flower shows, the arrangement of the parts on their axis or
receptacle is that of leaves upon the stem.
245. That the sepals and petals are of the nature of leaves is evident
from their appearance; they are commonly called the leaves of the
flower. The calyx is most generally green in color, and foliaceous
(leaf-like) in texture. And though the corolla is rarely green, yet
neither are proper leaves always green. In our wild Painted-cup, and in
some scarlet Sages, common in gardens, the leaves just under the flowers
are of the brightest red or scarlet, often much brighter-colored than
the corolla itself. And sometimes (as in many Cactuses, and in Carolina
Allspice) there is such a regular gradation from the last leaves of the
plant (bracts or bractlets) into the leaves of the calyx, that it is
impossible to say where the one ends and the other begins. If sepals are
leaves, so also are petals; for there is no clearly fixed limit between
them. Not only in the Carolina Allspice and Cactus (Fig. 229), but in
the Water-Lily (Fig. 228) and in a variety of flowers with more than one
row of petals, there is such a complete transition between calyx and
corolla that no one can surely tell how many of the leaves belong to the
one and how many to the other.
[Illustration: Fig. 228. Series of sepals, petals, and stamens of White
Water-Lily, showing the transitions.]
[Illustration: Fig. 229. A Cactus blossom.]
246. That stamens are of the same general nature as petals, and
therefore a modification of leaves, is shown by the gradual transitions
that occur between the one and the other in many blossoms; especially in
cultivated flowers, such as Roses and Camellias, when they begin to
_double_, that is, to change their stamens into petals. Some wild and
natural flowers show the same interesting transitions. The Carolina
Allspice and the White Water-Lily exhibit complete gradations not only
between sepals and petals, but between petals and stamens. The sepals of
our Water-Lily are green outside, but white and petal-like on the
inside; the petals, in many rows, gradually grow narrower towards the
centre of the flower; some of these are tipped with a trace of a yellow
anther, but still are petals; the next are more contracted and
stamen-like, but with a flat petal-like filament; and a further
narrowing of this completes the genuine stamen.
247. Pistils and stamens now and then change into each other in some
Willows; pistils often turn into petals in cultivated flowers; and in
the Double Cherry they are occasionally replaced by small green leaves.
Sometimes a whole blossom changes into a cluster of green leaves, as in
the "green roses" occasionally noticed in gardens, and sometimes it
degenerates into a leafy branch. So the botanist regards pistils also as
answering to leaves; that is, to single leaves when simple and separate,
to a whorl of leaves when conjoined.
Sec. 4. MODIFICATIONS OF THE TYPE.
248. =The Deviations=, as they may be called, from the assumed type or
pattern of flower are most various and extensive. The differences
between one species and another of the same genus are comparatively
insignificant; those between different genera are more striking; those
between different families and classes of plants more and more profound.
They represent different adaptations to conditions or modes of life,
some of which have obvious or probable utilities, although others are
beyond particular explanation. The principal modifications may be
conveniently classified. First those which in place of perfect
(otherwise called _hermaphrodite_ or bisexual) flowers, give origin to
249. =Unisexual, or Separated, or Diclinous Flowers=, _imperfect_
flowers, as they have been called in contradistinction to perfect
flowers; but that term is too ambiguous. In these some flowers want the
stamens, while others want the pistils. Taking hermaphrodite flowers as
the pattern, it is natural to say that the missing organs are
_suppressed_. This expression is justified by the very numerous cases in
which the missing parts are _abortive_, that is, are represented by
rudiments or vestiges, which serve to exemplify the plan, although
useless as to office. Unisexual flowers are
_Monoecious_ (or _Monoicous_, i. e. of one household), when flowers of
both sorts or sexes are produced by the same individual plant, as in the
Ricinus or Castor-oil Plant, Fig. 230.
_Dioecious_ (or _Dioicous_, i. e. of separate households), when the
two kinds are borne on different plants; as in Willows, Poplars, Hemp,
and Moonseed, Fig. 231, 232.
_Polygamous_, when the flowers are some of them perfect, and some
staminate or pistillate only.
[Illustration: Fig. 230. Unisexual flowers of Castor-oil plant: _s_,
staminate flower; _p_, pistillate flower.]
[Illustration: Fig. 231, staminate, and 232, pistillate flower of
Moonseed.]
250. A blossom having stamens and no pistil is a _Staminate_ or _Male_
flower. Sometimes it is called a _Sterile_ flower, not appropriately,
for other flowers may equally be sterile. One having pistil but no
stamens is a _Pistillate_ or _Female_ flower.
[Illustration: Fig. 233. Flower of Anemone Pennsylvanica; apetalous,
hermaphrodite.]
[Illustration: Fig. 234. Flower of Saururus or Lizard's-tail; naked, but
hermaphrodite.]
251. =Incomplete Flowers= are so named in contradistinction to complete:
they want either one or both of the floral envelopes. Those of Fig. 230
are incomplete, having calyx but no corolla. So is the flower of Anemone
(Fig. 233), although its calyx is colored like a corolla. The flowers of
Saururus or Lizard's-tail, although perfect, have neither calyx nor
corolla (Fig. 234). Incomplete flowers, accordingly, are
_Naked_ or _Achlamydeous_, destitute of both floral envelopes, as in
Fig. 234, or
_Apetalous_, when wanting only the corolla. The case of corolla present
and calyx wholly wanting is extremely rare, although there are seeming
instances. In fact, a single or simple perianth is taken to be a calyx,
unless the absence or abortion of a calyx can be made evident.
[Illustration: Fig. 235. Flower of Mustard. 236. Its stamens and pistil
separate and enlarged.]
[Illustration: Fig. 237. Flower of a Violet. 238. Its calyx and corolla
displayed: the five smaller parts are the sepals; the five intervening
larger ones are the petals.]
252. In contradistinction to regular and symmetrical, very many flowers
are
_Irregular_, that is, with the members of some or all of the floral
circles unequal or dissimilar, and
_Unsymmetrical_, that is, when the circles of the flower or some of them
differ in the number of their members. (Symmetrical and unsymmetrical
are used in a different sense in some recent books, but the older use
should be adhered to). Want of numerical symmetry and irregularity
commonly go together; and both are common. Indeed, few flowers are
entirely symmetrical beyond calyx, corolla, and perhaps stamens; and
probably no irregular blossoms are quite symmetrical.
253. =Irregular and Unsymmetrical Flowers= may therefore be illustrated
together, beginning with cases which are comparatively free from other
complications. The blossom of Mustard, and of all the very natural
family which it represents (Fig. 235, 236), is regular but unsymmetrical
in the stamens. There are four equal sepals, four equal petals; but six
stamens, and only two members in the pistil, which for the present may
be left out of view. The want of symmetry is in the stamens. These are
in two circles, an outer and an inner. The outer circle consists of two
stamens only; the inner has its proper number of four. The flower of
Violet, which is on the plan of five, is symmetrical in calyx, corolla,
and stamens, inasmuch as each of these circles consists of five members;
but it is conspicuously irregular in the corolla, one of the petals
being very different from the rest.
[Illustration: Fig. 239. Flower of a Larkspur. 240. Its calyx and
corolla displayed; the five larger parts are the sepals; the four
smaller, of two shapes, are the petals; the place of the fifth petal is
vacant. 241. Diagram of the same; the place for the missing petal marked
by a dotted line.]
[Illustration: Fig. 242. Flower of a Monkshood. 243. Its parts
displayed; five sepals, the upper forming the hood; the two lateral
alike, broad and flat; the two lower small. The two pieces under the
hood represent the corolla, reduced to two odd-shaped petals; in centre
the numerous stamens and three pistils. 244. Diagram of the calyx and
corolla; the three dotted lines in the place of missing petals.]
254. The flowers of Larkspur, and of Monkshood or Aconite, which are
nearly related, are both strikingly irregular in calyx and corolla, and
considerably unsymmetrical. In Larkspur (Fig. 239-241) the irregular
calyx consists of five sepals, one of which, larger than the rest, is
prolonged behind into a large sac or spur; but the corolla is of only
four petals (of two shapes),--the fifth, needed to complete the
symmetry, being left out. And the Monkshood (Fig. 242-244) has five very
dissimilar sepals, and a corolla of only two very small and
curiously-shaped petals,--the three needed to make up the symmetry being
left out. The stamens in both are out of symmetry with the ground-plan,
being numerous. So are the pistils, which are usually diminished to
three, sometimes to two or to one.
255. =Flowers with Multiplication of Parts= are very common. The stamens
are indefinitely numerous in Larkspur and in Monkshood (Fig. 242, 243),
while the pistils are fewer than the ground-plan suggests. Most
Cactus-flowers have all the organs much increased in number (Fig. 229),
and so of the Water-Lily. In Anemone (Fig. 233) the stamens and pistils
are multiplied while the petals are left out. In Buttercups or Crowfoot,
while the sepals and petals conform to the ground-plan of five, both
stamens and pistils are indefinitely multiplied (Fig. 245).
[Illustration: Fig. 245. Flower of Ranunculus bulbosus, or Buttercup, in
section.]
256. =Flowers modified by Union of Parts=, so that these parts more or
less lose the appearance of separate leaves or other organs growing out
of the end of the stem or receptacle, are extremely common. There are
two kinds of such union, namely:--
_Coalescence_ of parts of the same circle by their contiguous margins;
and
_Adnation_, or the union of adjacent circles or unlike parts.
257. =Coalescence= is not rare in leaves, as in the upper pairs of
Honeysuckles, Fig. 163. It may all the more be expected in the crowded
circles or whorls of flower-leaves. Datura or Stramonium (Fig. 246)
shows this coalescence both in calyx and corolla, the five sepals and
the five petals being thus united to near their tips, each into a tube
or long and narrow cup. These unions make needful the following terms:--
_Gamopetalous_, said of a corolla the petals of which are thus
coalescent into one body, whether only at base or higher. The union may
extend to the very summit, as in Morning Glory and the like (Fig. 247),
so that the number of petals in it may not be apparent. The old name for
this was _Monopetalous_, but that means "one-petalled;" while
gamopetalous means "petals united," and therefore is the proper term.
[Illustration: Fig. 246. Flower of Datura Stramonium; gamosepalous and
gamopetalous.]
[Illustration: Fig. 247. Funnelform corolla of a common Morning Glory,
detached from its polysepalous calyx.]
_Polypetalous_ is the counterpart term, to denote a corolla of
_distinct_, that is, separate petals. As it means "many petalled," it is
not the best possible name, but it is the old one and in almost
universal use.
_Gamosepalous_ applies to the calyx when the sepals are in this way
united.
_Polysepalous_, to the calyx when of separate sepals or calyx-leaves.
258. Degree of union or of separation in descriptive botany is expressed
in the same way as is the lobing of leaves (139). See Fig. 249-253, and
the explanations.
259. A corolla when gamopetalous commonly shows a distinction (well
marked in Fig. 249-251) between a contracted tubular portion below, the
TUBE, and the spreading part above, the BORDER or LIMB. The junction
between tube and limb, or a more or less enlarged upper portion of the
tube between the two, is the THROAT. The same is true of the calyx.
260. Some names are given to particular forms of the gamopetalous
corolla, applicable also to a gamosepalous calyx, such as
_Wheel-shaped_, or _Rotate_; when spreading out at once, without a tube
or with a very short one, something in the shape of a wheel or of its
diverging spokes, Fig. 252, 253.
_Salver-shaped_, or _Salver-form_; when a flat-spreading border is
raised on a narrow tube, from which it diverges at right angles, like
the salver represented in old pictures, with a slender handle beneath,
Fig. 249-251, 255.
[Illustration: Fig. 248. Polypetalous corolla of Soapwort, of five
petals with long claws or stalk-like bases.]
[Illustration: Fig. 249. Flower of Standing Cypress (Gilia
coronopifolia); gamopetalous: the tube answering to the long claws in
248, except that they are coalescent: the limb or border (the spreading
part above) is _five-parted_, that is, the petals not there united
except at very base.]
[Illustration: Fig. 250. Flower of Cypress-vine (Ipomoea Quamoclit);
like preceding, but limb _five-lobed_.]
[Illustration: Fig. 251. Flower of Ipomoea coccinea; limb almost
_entire_.]
[Illustration: Fig. 252. Wheel-shaped or rotate and five-parted corolla
of Bittersweet, Solanum Dulcamara. 253. Wheel-shaped and five-lobed
corolla of Potato.]
_Bell-shaped_, or _Campanulate_; where a short and broad tube widens
upward, in the shape of a bell, as in Fig. 254.
[Illustration: Fig. 254. Flower of a Campanula or Harebell, with a
campanulate or bell-shaped corolla; 255, of a Phlox, with salver-shaped
corolla; 256, of Dead Nettle (Lamium), with labiate _ringent_ (or
gaping) corolla; 257, of Snapdragon, with labiate _personate_ corolla;
258, of Toad-Flax, with a similar corolla spurred at the base.]
_Funnel-shaped_, or _Funnelform_; gradually spreading at the summit of a
tube which is narrow below, in the shape of a funnel or tunnel, as in
the corolla of the common Morning Glory (Fig. 247) and of the Stramonium
(Fig. 246).
_Tubular_; when prolonged into a tube, with little or no spreading at
the border, as in the corolla of the Trumpet Honeysuckle, the calyx of
Stramonium (Fig. 246), etc.
261. Although sepals and petals are usually all blade or lamina (123),
like a sessile leaf, yet they may have a contracted and stalk-like base,
answering to petiole. This is called its CLAW, in Latin _Unguis_.
_Unguiculate_ petals are universal and strongly marked in the Pink
tribe, as in Soapwort (Fig. 248).
[Illustration: Fig. 259. Unguiculate (clawed) petal of a Silene; with a
two-parted crown.]
[Illustration: Fig. 260. A small Passion-flower, with crown of slender
threads.]
262. Such petals, and various others, may have an outgrowth of the inner
face into an appendage or fringe, as in Soapwort, and in Silene (Fig.
259), where it is at the junction of claw and blade. This is called a
CROWN, or _Corona_. In Passion-flowers (Fig. 260) the crown consists of
numerous threads on the base of each petal.
[Illustration: Fig. 261. Front view of a papilionaceous corolla. 262.
The parts of the same, displayed: _s_, Standard, or Vexillum; _w_,
Wings, or Alae; _k_, Keel, or Carina.]
263. =Irregular Flowers= may be polypetalous, or nearly so, as in the
papilionaceous corolla; but most of them are irregular through
coalescence, which often much disguises the numerical symmetry also. As
affecting the corolla the following forms have received particular
names:
264. =Papilionaceous Corolla=, Fig. 261, 262. This is polypetalous,
except that two of the petals cohere, usually but slightly. It belongs
only to the Leguminous or Pulse family. The name means butterfly-like;
but the likeness is hardly obvious. The names of the five petals of the
_papilionaceous_ corolla are curiously incongruous. They are,
The STANDARD or _Banner_ (_Vexillum_), the large upper petal which is
external in the bud and wrapped around the others.
The WINGS (_Alae_), the pair of side petals, of quite different shape
from the standard.
The KEEL (_Carina_), the two lower and usually smallest petals; these
are lightly coalescent into a body which bears some likeness, not to the
keel, but to the prow of a boat; and this encloses the stamens and
pistil. A Pea-blossom is a typical example; the present illustration is
from a species of Locust, Robinia hispida.
265. =Labiate Corolla= (Fig. 256-258), which would more properly have
been called _Bilabiate_, that is, two-lipped. This is a common form of
gamopetalous corolla; and the calyx is often bilabiate also. These
flowers are all on the plan of five; and the irregularity in the corolla
is owing to unequal union of the petals as well as to diversity of form.
The two petals of the upper or posterior side of the flower unite with
each other higher up than with the lateral petals (in Fig. 256, quite to
the top), forming the _Upper lip_: the lateral and the lower similarly
unite to form the _Lower lip_. The single notch which is generally found
at the summit of the upper lip, and the two notches of the lower lip, or
in other words the two lobes of the upper and the three of the lower
lip, reveal the real composition. So also does the alternation of these
five parts with those of the calyx outside. When the calyx is also
bilabiate, as in the Sage, this alternation gives three lobes or sepals
to the upper and two to the lower lip. Two forms of the labiate corolla
have been designated, viz.:--
_Ringent_ or _Gaping_, when the orifice is wide open, as in Fig. 256.
_Personate_ or _Masked_, when a protuberance or intrusion of the base of
the lower lip (called a _Palate_) projects over or closes the orifice,
as in Snapdragon and Toad-Flax, Fig. 257, 258.
[Illustration: Fig. 263. Corolla of a purple Gerardia laid open, showing
the four stamens; the cross shows where the fifth stamen would be, if
present.]
[Illustration: Fig. 264. Corolla, laid open, and stamens of Pentstemon
grandiflorus, with a sterile filament in the place of the fifth stamen,
and representing it.]
[Illustration: Fig. 265. Corolla of Catalpa laid open, displaying two
good stamens and three abortive ones or vestiges.]
266. There are all gradations between labiate and regular corollas. In
those of Gerardia, of some species of Pentstemon, and of Catalpa (Fig.
263-265), the labiate character is slight, but is manifest on close
inspection. In almost all such flowers the plan of five, which is
obvious or ascertainable in the calyx and corolla, is obscured in the
stamens by the abortion or suppression of one or three of their number.
[Illustration: Fig. 266. Two flower-heads of Chiccory.]
[Illustration: Fig. 267. One of them half cut away, better showing some
of the flowers.]
267. =Ligulate Corolla.= The ligulate or _Strap-shaped_ corolla mainly
belongs to the family of Compositae, in which numerous small flowers are
gathered into a head, within an involucre that imitates a calyx. It is
best exemplified in the Dandelion and in Chiccory (Fig. 266). Each one
of these straps or _Ligules_, looking like so many petals, is the
corolla of a distinct flower: the base is a short tube, which opens out
into the ligule: the five minute teeth at the end indicate the number of
constituent petals. So this is a kind of gamopetalous corolla, which is
open along one side nearly to the base, and outspread. The nature of
such a corolla (and of the stamens also, to be explained in the next
section) is illustrated by the flower of a Lobelia, Fig. 285.
[Illustration: Fig. 268. Head of flowers of a Coreopsis, divided
lengthwise.]
268. In Asters, Daisies, Sunflower, Coreopsis (Fig. 268), and the like,
only the marginal (or _Ray_) corollas are ligulate; the rest (those of
the _Disk_) are regularly gamopetalous, tubular, and five-lobed at
summit; but they are small and individually inconspicuous, only the
_ray-flowers_ making a show. In fact, those of Coreopsis and of
Sunflower are simply for show, these ray-flowers being not only sterile,
but _neutral_, that is, having neither stamens nor pistil. But in
Asters, Daisies, Golden-rods, and the like, these ray-flowers are
pistillate and fertile, serving therefore for seed-bearing as well as
for show. Let it not be supposed that the show is useless. See Section
XIII.
[Illustration: Fig. 269. A slice of the preceding more enlarged, with
one tubular perfect flower (_a_) left standing on the receptacle, with
its bractlet or chaff (_b_), one ligulate and neutral ray-flower (_cc_)
and part of another; _dd_, section of bracts or leaves of the
involucre.]
269. =Adnation, or Consolidation=, is the union of the members of parts
belonging to different circles of the flower (256). It is of course
understood that in this (as likewise in coalescence) the parts are not
formed and then conjoined, but are produced in union. They are born
united, as the term _adnate_ implies. To illustrate this kind of union,
take the accompanying series of flowers (Fig. 270-274), shown in
vertical section. In the first, Fig. 270, Flax-flower, there is no
adnation; sepals, petals, and stamens, are _free_ as well as distinct,
being separately borne on the receptacle, one circle within or above the
next; only the five pistils have their ovaries coalescent. In Fig. 271,
a Cherry-flower, the petals and stamens are borne on the throat of the
calyx-tube; that is, the sepals are coalescent into a cup, and the
petals and stamens are adnate to the inner face of this; in other
words, the sepals, petals, and stamens are all consolidated up to a
certain height. In Fig. 272, a Purslane-flower, the same parts are
adnate to or consolidated with the ovary up to its middle. In Fig. 273,
a Hawthorn-flower, the consolidation has extended over the whole ovary;
and petals and stamens are adnate to the calyx still further. In Fig.
274, a Cranberry-blossom, it is the same except that all the parts are
free at the same height; all seem to arise from the top of the ovary.
270. In botanical description, to express tersely such differences in
the relation of these organs to the pistil, they are said to be
_Hypogynous_ (i. e. under the pistil) when they are all _free_, that is,
not adnate to pistil nor connate with each other, as in Fig. 270.
[Illustration: Fig. 270. Flax-flower in section; the parts all
free,--hypogynous.]
_Perigynous_ (around the pistil) when connate with each other, that is,
when petals and stamens are _inserted_ or borne on the calyx, whether as
in Cherry-flowers (Fig. 271) they are free from the pistil, or as in
Purslane and Hawthorn (Fig. 272, 273) they are also adnate below to the
ovary.
[Illustration: Fig. 271. Cherry-flower in section; petals and stamens
adnate to tube of calyx,--perigynous.]
[Illustration: Fig. 272. Purslane-flower in section; calyx, petals,
stamens, all adnate to lower half of ovary,--perigynous.]
_Epigynous_ (on the ovary) when so adnate that all these parts appear to
arise from the very summit of the ovary, as in Fig. 274. The last two
terms are not very definitely distinguished.
271. Another and a simpler form of expression is to describe parts of
the flower as being
_Free_, when not united with or _inserted_ upon other parts.
_Distinct_, when parts of the same kind are not united. This term is the
counterpart of coalescent, as free is the counterpart of adnate. Many
writers use the term "free" indiscriminately for both; but it is better
to distinguish them.
_Connate_ is a term common for either not free or not distinct, that
is, for parts united congenitally, whether of same or of different
kinds.
_Adnate_, as properly used, relates to the union of dissimilar parts.
272. In still another form of expression, the terms superior and
inferior have been much used in the sense of above and below.
_Superior_ is said of the ovary of Flax-flower, Cherry, etc., because
above the other parts; it is equivalent to "ovary free." Or it is said
of the calyx, etc., when above the ovary, as in Fig. 273-275.
_Inferior_, when applied to the ovary, means the same as "calyx adnate;"
when applied to the floral envelopes, it means that they are free.
[Illustration: Fig. 273. Hawthorn-blossom in section; parts adnate to
whole face of ovary, and with each other beyond; another grade of
perigynous.]
[Illustration: Fig. 274. Cranberry-blossom in section; parts epigynous.]
273. =Position of Flower or of its Parts.= The terms superior and
inferior, or upper and lower, are also used to indicate the relative
position of the parts of a flower in reference to the axis of
inflorescence. An axillary flower stands between the bract or leaf which
subtends it and the axis or stem which bears this bract or leaf. This is
represented in sectional diagrams (as in Fig. 275, 276) by a transverse
line for the bract, and a small circle for the axis of inflorescence.
Now the side of the blossom which faces the bract is the
_Anterior_, or _Inferior_, or _Lower_ side; while the side next the axis
is the
_Posterior_, or _Superior_, or _Upper_ side of the flower.
[Illustration: Fig. 275. Diagram of papilionaceous flower (Robinia, Fig.
261), with bract below; axis of inflorescence above.]
[Illustration: Fig. 276. Diagram of Violet-flower; showing the relation
of parts to bract and axis.]
274. So, in the labiate corolla (Fig. 256-258), the lip which is
composed of three of the five petals is the _anterior_, or _inferior_,
or _lower_ lip; the other is the _posterior_, or _superior_, or _upper_
lip.
275. In Violets (Fig. 238, 276), the odd sepal is posterior (next the
axis); the odd petal is therefore anterior, or next the subtending leaf.
In the papilionaceous flower (Fig. 261, and diagram, Fig. 275), the odd
sepal is anterior, and so two sepals are posterior; consequently, by the
alternation, the odd petal (the standard) is posterior or upper, and the
two petals forming the keel are anterior or lower.
Sec. 5. ARRANGEMENT OF PARTS IN THE BUD.
276. =AEstivation= was the fanciful name given by Linnaeus to denote the
disposition of the parts, especially the leaves of the flower, before
_Anthesis_, i. e. before the blossom opens. _Praefloration_, a better
term, is sometimes used. This is of importance in distinguishing
different families or genera of plants, being generally uniform in each.
The aestivation is best seen by making a slice across the flower-bud; and
it may be expressed in diagrams, as in the accompanying figures.
277. The pieces of the calyx or the corolla either overlap each other in
the bud, or they do not. When they do not overlap, the aestivation is
_Valvate_, when the pieces meet each other by their abrupt edges,
without any infolding or overlapping; as the calyx of the Linden or
Basswood (Fig. 277).
[Illustration: Fig. 277. Diagram of a flower of Linden, showing the
calyx valvate and corolla imbricate in the bud, etc.]
_Induplicate_, which is valvate with the margins of each piece
projecting inwards, as in the calyx of a common Virgin's-bower, Fig.
278, or
[Illustration: Fig. 278. Valvate-induplicate aestivation of calyx of
common Virgin's-bower.]
_Involute_, which is the same but the margins rolled inward, as in most
of the large-flowered species of Clematis, Fig. 279.
[Illustration: Fig. 279. Valvate-involute aestivation of same in
Vine-bower, Clematis Vitialla.]
_Reduplicate_, a rarer modification of valvate, is similar but with
margins projecting outward.
_Open_, the parts not touching in the bud, as the calyx of Mignonette.
278. When the pieces overlap in the bud, it is in one of two ways;
either every piece has one edge in and one edge out, or some pieces are
wholly outside and others wholly inside. In the first case the
aestivation is
_Convolute_, also named _Contorted_ or _Twisted_, as in Fig. 280, a
cross-section of a corolla very strongly thus convolute or rolled up
together, and in the corolla of a Flax-flower (Fig. 281), where the
petals only moderately overlap in this way. Here one edge of every petal
covers the next before it, while its other edge is covered by the next
behind it. The other mode is the
[Illustration: Fig. 280. Convolute aestivation, as in the corolla-lobes
of Oleander.]
[Illustration: Fig. 281. Diagram of a Flax-flower; calyx imbricated and
corolla convolute in the bud.]
_Imbricate_ or _Imbricated_, in which the outer parts cover or overlap
the inner so as to "break joints," like tiles or shingles on a roof;
whence the name. When the parts are three, the first or outermost is
wholly external, the third wholly internal, the second has one margin
covered by the first while the other overlaps the third or innermost
piece: this is the arrangement of alternate three-ranked leaves (187).
When there are five pieces, as in the corolla of Fig. 225, and calyx of
Fig. 281, as also of Fig. 241, 276, two are external, two are internal,
and one (the third in the spiral) has one edge covered by the outermost,
while its other edge covers the innermost; which is just the five-ranked
arrangement of alternate leaves (188). When the pieces are four, two are
outer and two are inner; which answers to the arrangement of opposite
leaves.
279. The imbricate and the convolute modes sometimes vary one into the
other, especially in the corolla.
280. In a gamopetalous corolla or gamosepalous calyx, the shape of the
tube in the bud may sometimes be noticeable. It may be
_Plicate_ or _Plaited_, that is, folded lengthwise; and the plaits may
either be turned outwards, forming projecting ridges, as in the corolla
of Campanula; or turned inwards, as in that of Gentian Belladonna; or
_Supervolute_, when the plaits are convolutely wrapped round each other,
as in the corolla of Morning Glory and of Stramonium, Fig. 282.
[Illustration: Fig. 282. Upper part of corolla of Datura Stramonium in
the bud; and below a section showing the convolution of the plaits.]