spore) that may have fallen upon the soft tissue of the
carpel stigma germinates there producing its most
reduced gametophyte, and a tubular antherid (pollen
tube). The latter penetrates the soft stigma tissues
toward the ovary cavity, carrying down the two sperms.
When the tubular antherid reaches the ovule it enters
the little pore (micropyle) at the summit of the indusial
coats, and penetrates the ovule to the egg where one of
the sperms then unites with the egg, this constituting
fertilization. The zygote now divides repeatedly and
288 PHYLUM XIV. AXTIIOPHYTA
finally takes the form of a verj^ small stem, tipped with
a root at one end, and bearing two rudimentary leaves
at the other. In the meantime the immature game-
tophyte resumes its development as the result of the
union of the second sperm nucleus with the two polar
nuclei to form the so-called endosperm nucleus, which by
its rapid division, with much delayed formation of cell
walls, results in the development of a mass of tissue
surrounding and nourishing the embryo sporophyte
and filling the growing ovule. It is now known as the
endosperm, but it is in reaUty only the belated game-
tophyte.
522. The ovule has now grown much in size. Ex-
ternally its outer coat has become thicker and harder,
•while internally the gametophyte has enlarged and solidi-
fied. A layer of cells at the base of the ovule now
becomes corky and checks the supply of water, drjdng
and hardening the whole ovule, and stopping further
growth. In this final state the ovule is called the
seed.
523. In the Buttercup the carpel enlarges to accom-
modate the growing ovule, but finally its tissues harden
and dry so that when the seed is mature it is contained
within the close-fitting wall of the old carpel and, in this
condition, it finally falls off from the flower axis and is
known as a fruit. The term "fruit," therefore, is here
used for the ripened carpel and its contained seed, and
in flowering plants this is the generally accepted signi-
fication of the term.
524. When these fruits fall to the ground and absorb
moisture, the eml^ryo plant in each seed renews its
growth, getting its food from the endosperm. At
length it is able to push out a root into the soil, and much
later it escapes wholly from seed and fruit and pushes up
WATER PLANTAIN 289
its stem and leaves to the light above ground, and be-
comes an independent plant (sporophyte).
525. The flower structure of the Water Plantain
(Alisma) is essentially the same as that of the Buttercup.
In it the flower axis is less enlarged, the carpels are
fewer, in only a single whorl (i.e. not spirally arranged),
and the stamens are usually six. The rounded, white petals
are in a whorl of three, and the pointed, green sepals are
also in a whorl of three. In the single ovule the develop-
ment of the megaspore and later of the egg is similar
to that in the Buttercup, as is also the growth of the
pollen tube, and the process of fertilization. The
endosperm develops as a belated gameto-
phyte, and the zygote divides repeat-
edly, eventually becoming a small stem
with a root at one end and a single ru-
dimentary leaf at the other. Here this fig. les.— Verti-
embryo sporophyte continues its growth flowl'r'^and^pi^tii)?*
until it has absorbed all of the endo-
sperm: as a consequence it is much larger than in the
Buttercup, and the seed at maturity contains no
endosperm.
526. The structure and behavior of the fruits (ripened
carpels with their contained seeds) are in no wise unlike
those in the Buttercup. So too the germination of the
seed inside of the ripened carpels is similar to what has
been described above. However, as there is no more
endosperm remaining in the seed, the embryo escapes
from it shortly after the root has appeared and pushes
up its stem and leaves to the light above ground, as an
independent plant (sporophyte).
527. A third example of a typical flower ma}^ be seen
in the Strawberry (Fragaria) in which the flower re-
sembles that of the Buttercup and the Water Plantain.
19
290 PHYLUAI XIV. AXTHOPHYTA
Here the flower axis is globularly enlarged somewhat as
in the Buttercup, and this is covered likewise with many
spirally arranged carpels (megasporophylls). At the
base of this globular body of carpels the axis is flattened
out into a rim or collar, on the margin of which the
stamens grow in several whorls of 5 or 10 each. On
this margin there grow also the five rounded, white petals,
and the five pointed, green sepals, both series in whorls.
The development of the single ovules
and the production of the egg are
(S^
<^=^ essentially the same as in the two
n^P£<^ preceding examples. After fertiliza-
tion the zygote develops into an em-
FiG 164— Vertical plan ^ryo plant cousistiug of a small stem
pistu)!'^^"^ ^°""" ^'""^ with a root at one end and two rudi-
mentary leaves at the other. The
endosperm which appeared in abundance after fertili-
zation is here wholly absorbed by the growing embryo,
so that at maturity the seed contains a large embryo,
and no endosperm.
528. While these changes are taking place in the seed
the carpel enlarges, and the inner layers of the ovary
cells thicken their walls into sclerenchyma, w^hile the
outer layers soften into a juicy flesh (parenchyma). The
ripe carpels are thus very small fruits consisting of a thin
flesh surrounding a tiny stone, which encloses a single
seed. The proper fruits of the Strawberry are these
small ripened carpels. When they fall to the ground the
contained seed germinates by pushing out the root of
the embryo, and since there is no remaining endosperm
this is quickly followed by the escape of the remainder
of the plant from seed and carpel, when it pushes its stem
and leaves into the light, becoming an independent plant
(sporophyte).
STRAWBiaiUY 291
529. Here it should bo said that in the Strawl)erry
while the fruits are developing the gloi)ular flower axis
enlarges very greatly, and its tissues become soft and
juicy, and this is wdiat we eat with so much relish. So
the ''strawberry" as we eat it is not a
fruit properly speaking. It is a thickened
flower axis (stem), covered with the tiny
proper fruits, popularly supposed to ])e
^^^^^' Fig. 165.— Fm-
garia ("straw-
Laboratory Studies. Xote: In connection tnic^fVuit)^'^
with the anatomical studies of special plants
suggested below the student is referred to the general studies
on the cell, tissues, and tissue systems, already taken up in
Chapters I, II, and III respectivel}'.
In working out the following studies the student should have
before him specimens of the three plants named so as to make
comparative studies of the structures represented by them. —
(1) Ranunculus, (2) Alisma, and (3) Fragaria. Where these
cannot be obtained, acceptable substitutions may be made as
follows: for (1) Myosurus, Magnolia, Caltha, Hepatica,
Anemone; (2) Sagittaria; (3) Potentilla, Rubus, Geuni,
Duchesnea.
(a) Make a macroscopic examination of the stems (of the
sporophytes) noting their shape, nodes, branching, bud and
leaf arrangement, and follow with a microscopic examination of
(i) a cross-section to show the location and structure of the vas-
cular bundles, and the distribution of green and colorless
tissues; and (ii) a longisection to show the tissues, epidermis,
hairs and stomata.
{}}) Examine the roots (of the sporophytes) and note whether
there is one main root (tap root) with lateral rootlets, or a
cluster of roots arising from about the same point on the stem.
Note the shape, size and character of the roots and rootlets.
Make cross- and longisections of the younger and older parts
and a longisection of the tip of a root, to study the location and
character of the vascular bundles, the kinds and distribution
of tissues, the origin of lateral roots, the character of the root
cap, etc.
292 PHYLUM XIV. ANTHOPHYTA
(c) Make a similar macroscopic examination of the leaves (of
the sporophytes), noting whether they arise singly at the nodes
("alternate" leaves), or in pairs ("opposite"), or in whorls of
three or more ("whorled"); determine the shape (sometimes
variable), margin, surface, size and variation of the leaf blades;
the length and shape of the petioles; and the shape and position
of the stipules (where present). For the microscopic anatomy
make cross-sections of the leaves and note shape and size of
the epidermal cells, thickness of cuticle, character of hairs,
type and location of vascular bundles (veins), and amount and
location of the forms of parenchyma tissue (the mesophyll)
called "pahsade" and "sponge" parenchyma respectively.
In cross-sections of the petioles note size of intercellular spaces.
Make sections of the blade parallel to the surface, and note the
comparative frequency of the stomata in the upper and lower
epidermis, shape of epidermal cells (and correlation with type
of venation if any), component tissues of the veins and the
course of the latter, etc.
(d) Study the macroscopic structure of the flowers observing
them from above, note that they are radially symmetrical (ac-
tinomorphic). Note the shape of the axis (torus) and how the
flower parts are attached to it, making a longitudinal section if
necessarj^; observe that it does not surround or grow fast to
any floral parts. Note the number and arrangement (in spirals
or whorls) of the megasporophylls (carpels), and observe that
they are free from one another (apocarpous) ; distinguish the
ovar}' and stigma (and style if present); make transverse and
longitudinal sections of carpels and observe number and loca-
tion of the megasporangia (ovules). Count and note arrange-
ment (in spirals or whorls) of the microsporophylls (stamens) ;
examine one carefull}^ and note the filament (stalk) and anther
(cluster of microsporangia); section transversely an unopened
anther and note the four microsporangia; examine the mi-
crospores (pollen) from a mature anther. For the petals note
number, shape, color, size, and particularly their arrangement
(spirals or whorls). Make a similar study of the sepals; note
whether free or united; observe their arrangement with refer-
ence to the petals.
(e) The study of the female gametophyte will require the
use of prepared slides. If possible they should show the devel-
opment from the megaspore mother-cell (archespore) to four
COMPARISON OF FLOWER TYPES 203
megasporcs, thence to the formation of the immature gameto-
phyte (embryo sac) with its egg, arrangement of cells and nuclei
being noted. A slide should also be studied in which a young
sporophyte is developing amid the cells representing the
further growth of the gametophyte (i.e. the endosperm).
The male gametophyte may also be studied in a prepared slide
showing microspores (pollen cells) that have been germinated
so as to show the tubular antherids (pollen tubes) and which
should also show the antheridial nucleus, and the generative
nucleus (or possibly the two non-ciliated sperms derived from
(/) Strictly considered the fruits consist of the modified
carpels containing the ripe seeds, but any accessory modification
of adjacent parts should also be noted. Examine the flowers
when the fruits are mature and note the structure of the carpels,
whether dry or partly fleshy, and dehiscent (i.e. opening to per-
mit the escape of the seeds) or not (indehiscent). Note (in
Fragaria or Duchesnea) the considerable enlargement of the
torus, and consequent separation of the carpels. Note how the
calyx is modified, and whether it remains or falls. Remove a
mature seed from a carpel and note its size and shape, and the
external characters of the seed coat (consisting of the integu-
ments); section it transversely and longitudinally and deter-
mine the presence or absence of endosperm, the relative size
of the embryo, and the number of cotyledons.
530. If now we compare the three flowers described
above it will be seen that they are very similar. Yet
the Buttercup and Strawberry have their petals and
sepals in whorls or series of five each, while they are in
whorls of three each in the Water Plantain. Again in
the former there are tw^o rudimentary leaves (''cotyle-
dons") on the embryo sporophyte, wdiile in the latter
there is but one. Now if we carry our comparison to the
plants bearing the flowers we find other differences. The
first leaves on the little plant in the Buttercup and the
Strawberry as it appears above ground are opposite on the
stem, while in tlie Water Plantain thev are alternate,
294 PHYLU.M XIV. ANTHOPHYTA
and continue to be so throughout the life of the plant.
In the first two the vascular bundles of the leaves are
irregularly netted with one another, while in the Water
Plantain the bundles are quite as markedly parallel.
Also in the stems of the first two there is a more or less
cylindrical arrangement of the vascular bundles, showing
as a ring in a cross-section, while in the Water Plantain
the bundles show little if any cylindrical arrange-
ment, the bundles being more or less scattered through-
out the cross-section.
531. These differences are pretty constant for the
plants related to Buttercups, Strawberries and Water
Plantains respectively, so that botanists have been
led to use them for the division of the Flowering Plants
into two classes. Thus the first two plants and their
relatives constitute the Class Dicotyledoneae, that is the
plants with two cotyledons, while the Water Plantains
and their relatives constitute the Class Monocotyledoneae
that is the plants with one cotyledon. These classes are
of very unequal size, the Dicotyledons containing nearly
109,000 species, while the Monocot-
yledons contain somewhat less than
24,000 species.
632. It is now thought that the
Dicotyledons originated earlier
than the Monocotyledons, and that
the latter must be considered an
^'''â– Fiowe;[;.?p[an^s.*^' early offshoot of the former. Yet
the Monocotyledons are by no
means higher in rank than the Dicotyledons as a whole;
they show fewer variations from a common type; they
are more nearly uniform in structure and at no point do
they rise as high as do many of the Dicotyledons. For
these reasons the Monocotyledons are usually discussed
MONOCOTYLEDONS 295
before the Dicotyledons, as a lower class, in sj)ite of the
fact that they appear to have originated from the latter.
The Dicotyledons are an earlier class, but they have
risen higher than the later derived Monocotyledons.
CLASS MONOCOTYLEDONEAE.
The Monocotyledons
533. Cotyledon one; leaves on the stem alternate;
vascular bundles in the stem scattered (as seen in cross-
section), in the leaf blades parallel (''parallel-veined");
perianth whorls mostly ternate (in 3's).
534. There are seven or eight types (orders) of Mono-
cotyledons. The lowest of these (Alifitnatales) is rep-
resented by the Water Plantain, already described.
The others are briefl}^ as follows:
535. Lilies (Liliales). In a Lily the carpels (mega-
sporophylls) have been reduced to three, and these have
grown together into a single pistil (''com-
pound pistil"), in which each carpel
retains its ovule-bearing cavity (i.e. the
pistil is "3-celled"). The stamens (mi-
crosporophylls) are in two whorls of
three each: the petals are three; and the p^^ ig7— Liiium
sepals three. Commonly the perianth is ^vi'rse '^'Vansf ^'^''"'*"
relatively large, and the two whorls of
similar texture. Throughout the flower the members of
successive whorls are alternate.
536. The flower structure here reached appears to be
typical of the great body of the Monocotyledons; and the
structural ]MH'uliarities of the following orders are only
modifications of those of the Lilies.
537. Calla Lilies (Aralcs). In the Calla Lilies the
individual flowers are small, and massed on a thick
296 PHYLU^I XIV. AXTHOPHYTA
stem, commonly diclinous (i.e. stamens and pistils in
separate flowers, monoecious or dioecious) usually sub-
tended V)y a colored leaf (spathe). Each flower is like a
very small lily, but it is very short verti-
cally, and relatively thick ('"squatty")-
The short stamens are usually six, and
the very short-styled pistil is 3-celled (or
^i68"^aiia l-ceflcd). The perianth lobes are short,
pSiKPoThTs).'"^ thick and fleshy or wanting. Through-
out the order (w^hich is largely tropical)
there is a marked tendency toward fleshiness both as to
the plant body (always herbaceous) and the flowers.
538. Palms {Palmales). This order of woody trees
and coriaceous leaves has small flowers resembling those
of the Lilies, but with the parts usually harder and more
parchment-like in texture. In the Coconut the flowers
are separated (diclinous), one kind having functional
stamens (staminate), and the other a functional pistil
(pistillate) . The staminate flower has a perianth of two
ternate whorls, the outer (sepals) shorter than the
inner (petals). The stamens are six in two whorls, and
there is a small, tricarpellary functionless pistil. The
pistillate flower is much larger, and
has a perianth of two ternate whorls,
the sepals and petals being similar to
each other. There are no stamens.
The large pistil is tricarpellary and
should contain a seed in each of the
, 1 , , 1 1 Fig. 169. — Palm flowers
carpels, but two seeds are always (Cocos).
suppressed and their carpellary cavi-
ties are crushed by the growth of the third large
seed. The fruit has much the structure of a plum;
in which the inner part of the ovary wall becomes
stony (sclerenchyma), while the outer part remains
GRASSES
2u:
flesh}' in the plum, but eventually becomes fibrous in the
coconut. The coconut of the northern markets is the
stone of the ovary wall, containing one large seed. This
stone shows its tricarpellary structure by the ridges on
its surface.
539. Grasses {Graminales) . In these plants (includ-
ing several families) the stems and leaves have become
elongated and markedly fibrous and tough. The flowers
are of the Lily type but much reduced, and are clustered
uniformly on slender axes into ''spikelets.'^ In the
Grasses proper (Family Poaceae) each flower is in the
axil of an outer bract (flowering glume, flowering scale,
lemma). The perianth consists of a scale-like, 2-keeled
calyx (palet, palea) representing the two united posterior
sepals (the third being absent) and of two (anterior),
rarely three, small, flesh}^ petals (lodicules). Two whorls
of three stamens each are present, or more often only
the outer whorl. The pistil is tri-
carpellary with two stigmas (very
rarely three stigmas) and there is
but one ovule in the single ovary
cavit3\
540. The Bamboos are large,
woody, hollow-stemmed tropical
grasses, in which the corolla is
trimerous, with the petals (lodicules)
relatively large, the stamens are mostly six, and the
pistil is frequently tristigmatic. In some bamboos the
fruit is externally flesh}', while in others it is like that
in the Brome Grasses.
541. Brome Grass (Bromus) has a hollow herbaceous
stem, and its large spikelets are several flowered; the
corolla is reduced to two small petals (lodicules) ; the
stamens are three, and the pistil has two feathery
Fig. 170. — Grass flowers
and spikelet.
298 PHYLUM XIV. AXTHOPHYTA
stigmas. The ripened pistil tightly encloses the seed,
forming the "grain" or ''caryopsis."
542. Maize (Indian Corn) has a solid (not hollow)
stem and its spikelets are diclinous, the staminate form-
ing a branching inflorescence at the top of the stem, the
pistillate being crowded upon the lateral ''ears," which
terminate short lateral branches, whose numerous
crowded leaf sheaths form the ''husks." The staminate
spikelets are in pairs (one sessile, the other stalked),
and each is two-flowered. The pistillate spikelets are
also in pairs, but here there is only one flower in each.
The styles ("silks") are long, and bistigmatic. The
corn "kernel" is the ripened ovary with its tightly
fitting single seed.
543. The Sedges (Family Cyperaceae) are a family
of widely distributed, somewhat more primitive, grass-
like plants that differ in vegetative structure from the
Grasses in that the leaves are three-ranked, instead of
two ranked, and the stems solid instead of hollow. The
spikelets more often have the bracts spirally arranged,
only a few genera having them two-ranked as in the
grasses. The axillary flower consists of a tri- or a bicar-
pellary pistil, six, or more often three, stamens, and a
perianth of two ternate whorls of
narrow segments, or bristles or want-
ing. The ovary wall is not grown
fast to the single seed.
544. Amaryllis {Iridales). In the
Amaryllis the flower is Lily-like with
Fig. 171.— Amaryllis ^ ^^^^^ dcvclopcd perianth of six equal
petaloid segments (sepals three, petals
three), six stamens, and a tricarpellary, long-styled pistil,
whose ovary is overgrown by the receptacular cup which
carries up the perianth and stamens, so that the ovary
ORCHIDS 299
is said to be ''inferior.'' The nearl}' related Iris has its
sepals reflexed and its petals erect: its stamens are three,
and the three style branches are broad and spreading.
The ovary is inferior as in Amaryllis.
545. Orchids (Orchidales). Here the ovary is in-
ferior as in AmaryUis, but the
perianth is made up of unequal
and unlike segments, the stamens
are reduced to two or one (very
rarely three), and the tricarpel-
lary pistil has but two functional
stigmas in the large majority of ^'^- â– ^^fu^^nd or ^[pfP"^^
species.
546. In all the foregoing Monocotyledons the embryos
have one cotyledon, the stems have scattered vascular
bundles, the leaves are alternate on the stems, and paral-
lel-veined, and the perianth whorls are ternate.
Laboratory Studies. Note: In these studies, and those
upon Dicotyledons, the aim should be to bring out the succes-
sive advances in flower structure from the lower to the higher
forms. With this object in view many other details may well
be omitted, but some attention should be given also to special
modifications of the general plant body.
(a) Make cross- and longitudinal sections of onion seeds and
note the seed coats (integuments) enclosing the rather horny
endosperm witliin which lies tlie embrj'o sporoi)hyte. In
similar sections of grains of Indian corn the external coat con-
sists of the ovary wall grown fast to the integuments; the
remainder of the grain consists of endosperm except the elon-
gated or shield-shaped "germ," which is the embryo sporo-
phyte.
(6) Sow a number of onion seeds and grains of Indian corn
and examine one of each every day after germination begins.
In the onion note that the plantlet "backs out" of tlie seed, as
it were, the root first appearing, followed by tlie stem, and last
of all, tlie single cotyledon. In the corn tlie cotyledon remains
in the grain as a si)ecial absorbing organ, so that after the root
300 PHYLUM XIV. ANTHOPHYTA
emerges the leaves appear, the short stem remaining in the seed
for some time before it begins to elongate.
(c) For the lilies use any true lil}' (Lilium) or one of the
following: Erythronium, Yucca, Allium, or TrilHum. By
longitudinal and transverse sections of the flowers show the
single, superior, tricarpellary pistil, the double, trimerous
whorl of stamens, the three petals, and the three sepals.
(d) In like manner examine the small flowers of any culti-
vated ''Calla Lily" (or Arisaema, Pothos, or Acorus), and note
also the thick axis (spadix) on which the flowers are collected,
and the large, subtending bract (spathe). Look for more or
less reduction in the structure of the flowers in some of these
plants.
(e) The lily-like staminate flowers of the Coconut (Cocos
nucifcra) should be studied like those of the true lilies (c) for
general plan, and the pistillate flowers for a considerable modi-
fication of that plan. Add a study of the mature nut. The
perfect flowers of the palmettos (Sabal) are much like the
staminate flowers of the coconut, but the fruits may develop
one, two or three of their carpels.
(/) Examine segments of Bamboo stems for woodiness. Dis-
sect Bamboo spikelets, noting their general structure; study the
flowers with their nearly complete perianth whorls, three or six
stamens, and two or three stigmas.
(g) A further reduction of the flower structure together with
a typical, not much reduced, spikelet structure, may be found
in the herbaceous grasses Bromus, Poa, Triticum, or Avena.
Study the spikelet structure, and then the flowers, in which
both perianth whorls are incomplete, one whorl of stamens is