The flowers are regular, _hypogynous_, nearly always unisexual, _small_
and insignificant, with _single_, green perianth of 4–5 leaves. Stamens
4–5, _placed opposite_ the leaves of the perianth. Ovary formed of 1
or 2 carpels, most frequently _unilocular_, with one ovule (Fig. 340).
The fruit is a _nut_, more rarely a drupe, with one seed, _generally
endospermous_. ~The Nettles are the sole order in the family which has
only one carpel (1 stigma); this turns the posterior side to the front
(Fig. 340). The others have two carpels (2 stigmas) but the anterior
only is fertile (Fig. 346) except in a few Ulmaceæ and Moraceæ.~
The majority are trees or shrubs with petiolated leaves, _stipulate_;
_rough hairs_ are very frequently developed upon the leaves. The
flowers are very often crowded together in the inflorescence, which is
rarely catkin-like. Peculiar aggregations of fruits are found in some
orders. _Latex_ and tough _bast_, which is used technically, are also
frequently found. Cystoliths are found in the epidermis of many species
of _Ficus_, _Urtica_, and others. ~_Wind-_ or _self-pollination_
is most common, as in the Quercifloræ and Juglandifloræ.~ In ~the
Urticaceæ, _Morus_ and some others, the stamens lie incurved in the
bud, and when ripe straighten themselves suddenly and elastically,
and thus small clouds of pollen-grains are ejected with considerable
violence on to the stigmas, which are often provided with brush-like
hairs (Fig. 341). The formation of honey does not take place.~
Order 1. =Ulmaceæ= (=Elms=).--Trees or shrubs without latex. Leaves
simple, arranged in two rows (divergence 1/2), oblique (the inner side,
nearer the axis, being the larger), strongly penninerved, dentate,
hispid; stipules deciduous. In opposition to the other Nettle-like
plants the flowers are often ☿ with a united cup- or saucer-like,
generally 4–(5)–6-divided perianth, and a corresponding or larger
number of opposite _erect_ stamens. The gynœceum has two carpels
(2 stigmas), generally one loculus with one pendulous, anatropous
or amphitropous ovule,[35] seldom two loculi and 2 ovules. Fruit
one-seeded (nut or drupe). Embryo without endosperm.
=A.= ULMEÆ. The fruit is a _winged nut_ (Fig. 339), the embryo
straight, without endosperm. Anthers extrorse.--_Ulmus_ (Elm). The
flowers are situated in inflorescences which develop from the lower
buds of the shoot of the preceding year. ~The lowermost bud-scales
are empty, the uppermost support either solitary flowers, or small,
dichasial or unipared scorpioid inflorescences. The terminal bud on the
vegetative shoot quickly falls off, and the upper lateral bud continues
the growth sympodially. Flowering takes place before the leaf-buds
open. The flowers are wind-pollinated and have no honey. Fossil species
have been found in the Oligocene.~
20 species; North Temp. (2 species in this country). Important
as timber. The Cork-elm (_U. suberosa_) has a rather thick cork,
which, however, is of no technical use. The bast is used as
Lime-bast.
=B.= CELTIDEÆ. The fruit is a drupe, the embryo curved, with
folded or rolled up cotyledons, with or without endosperm.
The anthers are introrse. The flowers are borne on a shoot of
the same year. _Planera_ (N. America); _Zelkova_.--About 114
species; especially N. Temp., Trop.
[Illustration: FIG. 339.--_A Ulmus campestris_, flower with
exceptionally aborted gynœceum; _B_, _U. effusa_, flower with
8 stamens; _C_, _U. campestris_, fruit opened in front to show
the seed pendulous from the apex of the loculus; one loculus is
aborted.]
Order 2. =Urticaceæ= (=Nettles=).--The majority of species are herbs
with simple, stipulate leaves; they have _no latex_; _stinging
hairs_ abundant. The flowers (Fig. 340) are _unisexual_, generally
2-merous and arranged _in clusters_, which are united into catkin-like
inflorescences. The perianth is composed very often of 4 (2 + 2)
free, or in the ♀-flowers generally united, green leaves; the 4 (2
+ 2) stamens are opposite the perianth-leaves, the filaments are
_bent inwards_ in the bud and throw themselves elastically towards
the outside. The gynœceum has _one style_ and _one stigma_ (capitate
or brush-like, Fig. 341); the ovary is unilocular, with _one
orthotropous_, _erect_ ovule (all other orders of this family have
inverted or curved ovules). Fruit, a nut or drupe. _Endosperm present_
(in _Urtica_ very little), oily. Embryo straight. ~The STINGING HAIRS
are club-shaped, very turgid, and provided with a siliceous, brittle
apex, which breaks off in an oblique direction and allows the poisonous
cell-sap to be forced out. In many tropical Nettles this is so strong
that it may produce partial paralysis. There is no rudiment of an ovary
in the ♂-flowers (Fig. 340 A). The PERIANTH in the ♀-flower differs
from that of the ♂ in having the two internal leaves generally much
larger and enveloping the fruit (Fig. 340 _B_); it often happens that
all the perianth-leaves are united to form a gamophyllous envelope.
☿-flowers may occur among the others.--THE INFLORESCENCES among our
native species are dichasia, which become transformed into unilateral
scorpioid cymes by the development of the bud of the 2nd bracteole. In
_Parietaria_ they are more pressed together, and the floral-leaves at
the same time are also raised on their axillary shoots to just beneath
the flower. As a rule, not only in this order but also in those related
to it, a small vegetative branch is situated in the axil of the
foliage-leaf, and this bears an inflorescence on each side at its base.~
_Urtica_ (Nettle) has opposite leaves with distinct stipules and
stinging hairs. The perianth-leaves of the ♀-flower are free (Fig.
340).--_Parietaria_ (Pellitory) has scattered leaves without large
stipules, and stinging hairs are absent. The ♀-perianth is 4-toothed,
flask- or bell-shaped.--~_Pilea_ is a tropical genus with trimerous,
zygomorphic ♀-flowers, the posterior perianth-leaf being much larger
than the two others, and more or less hood shaped.--The flower of
_Forskohlea_ is the most reduced; the ♂-flower has only one stamen, and
the ♀-as well as the ♂-flowers have a one-sided, tongue like perianth
(?). _Pouzolzia._~
[Illustration: FIG. 340.--Diagram of ♂-and ♀-flowers of _Urtica
dioica_.]
[Illustration: FIG. 341.--_Parietaria diffusa_; hermaphrodite
flower: _a_ in the female, _b_ at the commencement of the male
stage; the stigma has fallen off, but the anthers have not yet
dehisced.]
WIND-POLLINATED. The pollen is shot out of the anthers, when
they spring forward, and is caught by long stigmatic hairs.
_Parietaria diffusa_ is protogynous (Fig. 341).
500 species; chiefly in the Tropics, although the few species
which occur in Europe are represented by a much larger number
of individuals.--USES. The bast of the native species _Urtica
dioica_ and _urens_, of _U. cannabina_ (Siberia), etc.; of
_Boehmeria nivea_ “Ramié” and “China-grass” (from Sunda Is.,
China), and others, is used in the manufacture of muslin.
Order 3. =Moraceæ= (=Mulberries=). Nearly all trees or shrubs, seldom
herbs, generally with latex. The leaves are scattered, and not
infrequently lobed. The flowers are _unisexual_ (monœcious or diœcious)
and arranged in catkin- or capitulum-like, compound inflorescences.
Perianth-leaves 2–6, generally 4, with an equal number of stamens
opposite to them, as in the Nettles. The ovary is 1–seldom 2-locular,
and has 2 stigmas (it is thus formed from 2 carpels) seldom only one
style with one stigma. One ovule in each loculus, more or less curved,
and _pendulous_; micropyle directed upwards. Fruit usually a drupe.
The embryo is generally curved inside the _fleshy endosperm_, or it is
exendospermous.
[Illustration: FIG. 342.--_Morus alba_ ♂ flower (6/1).]
[Illustration: FIG. 343.-_Morus alba_ ♀ inflorescence.]
[Illustration: FIG. 344.--_Morus nigra_ fruits.]
=A.= MOREÆ. The filaments are incurved in the bud. Leaves folded in the
bud--_Morus_ (Mulberry) (Figs. 342–344). Monœcious. The inflorescences
are catkin-like in appearance, but in reality composed of many small
dichasia. The flowers are similar to those of the Nettle, but with 2
carpels: in the ♂ with perianth 2 + 2, and stamens 2 + 2 (Fig. 342),
in the ♀, perianth 2 + 2, and 2 carpels in regular alternation. The
small drupes are enveloped by _the perianth, which eventually becomes
fleshy_, and as all the flowers on the axis very accurately fit
together, the collection of fruits is formed, which we call a Mulberry
(Fig. 344). The leaves are folded in the buds, and have small stipules.
~The following are allied to _Morus_:--_Maclura_, _Broussonetia_ (the
Paper-mulberry tree) which has spheroid ♀ inflorescences (made up of
dichasia), etc.~
_Dorstenia_ presents an interesting transitional form to the Fig
in its flat, open, and, in some instances, lobed inflorescence
on which the ♂ and ♀ flowers are sunk in grooves. Indications
of a somewhat similar structure are found in certain Nettles,
the sympodial axes of the dichasia becoming flatly expanded. The
fruits are 1-seeded, but, nevertheless, spring open and eject
their seeds.
=B.= ARTOCARPEÆ. Filaments straight in the bud; foliage-leaves with
convolute vernation. An interpetiolar leaf-sheath (ocrea) formed in the
axil of each leaf by the connate stipules, covers the younger leaves
as a hood. It falls off as the leaf expands, and leaves a ring-like
scar on the stem.--_Ficus_ (the Fig). The inflorescence (the so-called
syconus) has a pear-shaped, fleshy, but hollow axis, on the interior
surface of which the flowers are situated (Fig. 345). It is a kind
of capitulum, with a hollow receptacle, whose “involucral” leaves
close over the entrance to the interior; it is not, however, a simple
capitulum, but a coalescence of cymose inflorescences. The edible parts
are the fleshy stem-portion and perianth-leaves. The ♂-flower has a
2–6 divided perianth, 1–2 (–6) stamens; the ♀-flower has an oblique
ovary. The fruits are drupes, with thin flesh.--~Many species have
aerial roots, and some live as epiphytes on trees. POLLINATION, in the
edible Fig, is effected by a small Gall-wasp (_Cynips psenes_ L.),
which lays its eggs in the Fig, and hence carries the pollen away. Even
in very ancient times it was customary to hang infected wild Figs on
the branches of cultivated ones, so that the young Gall-wasps, as they
emerged, could immediately effect the pollination (caprification).
_Ficus carica_, and other species, have two kinds of ♀-flowers, besides
the ♂-flowers. One kind has a short style and no stigmatic hairs,
and it is only in the ovaries of these that the wasps lay their eggs
(gall-flowers); the other kind has a long style and well-developed
stigmatic-hairs, but the wasps cannot reach their ovaries--these are
“seed-flowers.” There are, moreover, two kinds of plants of _Ficus
carica_; ♀-plants, which have only seed-flowers, and bear the edible
Figs, and ♂-plants (called “Caprificus”), which bear inedible fruits,
and have ♂-flowers at the upper part of the Fig, but gall-flowers at
the base. [The Caprificus, at Naples, bears three crops of inedible
Figs each year, viz. _Mamme_ (April), _Profichi_ (June), _Mamnoni_
(August). The ♂-flowers are produced especially in June, the first
Figs being almost entirely ♀, and the last having but few ♂-flowers.
Each crop produces a new generation of Fig-wasps. The female wasp
enters the Figs on the Caprificus, and lays one egg in each flower,
with the result that the flower developes into a kind of gall. The
mother-wasp dies within the Fig. The male wasp is wingless; it bites
a small passage into the ovaries containing the female wasps, and
impregnates them; the female wasps then escape from the Fig, those in
the _Profichi_ carrying pollen away with them as they pass out. They
then enter another Fig, lay their eggs, and die. The edible Fig-tree
similarly has three crops in the year, _Fiori di fico_, _Pedagnuoli_,
_Cimaruoli_. The wasps, entering these Figs, are unable to lay their
eggs in the ovary, but, nevertheless, they effect cross-pollination on
entering the _Pedagnuoli_, which bear fertile seeds.]~
[Illustration: FIG. 345.--A Fig in longitudinal section.]
The flowers of _Brosimum_ are the most reduced. The perianth
is wanting, and the ♂-flower has only 1 stamen. _Cecropia_
(Trumpet-tree), in S. Am., has its pith divided into chambers;
these are inhabited by ants, which feed upon small food-bodies
formed on the swollen base of the petioles. The leaves are
petiolated, often shield-like, fringed or lobed, and sometimes
with white felted hairs. They serve as food for _Bradypus_
(the Sloth). _Sorocea_; _Castilloa_.
About 300 species exclusively in the warmer climates. The white
Mulberry (_M. alba_, from China, India, Mongolia) is cultivated
for the sake of its leaves, which are the indispensable food
for silkworms. The black Mulberry (_M. nigra_, W. Asia) is
cultivated for its fruits, which are used for the officinal
Mulberry juice. The ordinary Fig-tree (_Ficus carica_) is from
the Mediterranean. The fruit of the well-known Oriental Sycamore
(_F. sycomorus_) is edible. The Bread-fruit tree (_Artocarpus
incisa_) and the Jack (_A. integrifolia_) have their home in the
South Sea Islands, and are cultivated in tropical countries.
The Bread-fruit is morphologically the same as the Mulberry. It
has a very large, spheroid inflorescence, whose floral-leaves
and perianth become fleshy and united into one nutritious mass,
together with the axis, which is also fleshy. The milky juice
of the India-rubber tree (_Ficus elastica_, East Indies, a
common house-plant), and of _Castilloa elastica_ (Am.) is the
raw material of India-rubber. The milky juice of _Galactodendron
utile_ (Cow-tree, S. Am.) is saccharine and nutritious, but in
_Antiaris toxicaria_ (the Upas-tree, of Java) it is a strong
poison. The bast of the Paper-Mulberry tree (_Br. papyrifera_,
Eastern Asia); is used in Japan for paper. Shellac is obtained
from a small, hemipterous insect (_Coccus lacca_), which lives
upon _Ficus laccifera_ and _F. religiosa_ (the Bo-tree, sacred
to Buddha), E. India. The wood of _Maclura aurantica_ (Am.) has
a yellow colour, and is known as yellow Brazilian wood.
Order 4. =Cannabaceæ.= The plants which belong to this order are
_aromatic herbs_, either annuals or perennials, _without latex_.
Leaves _palminerved_, and more or less divided, hispid, and with free,
persistent stipules. Flowers always _diœcious_; ♂-flowers in panicles,
formed of dichasia, passing over into uniparous scorpioid cymes. They
differ from the Nettles, particularly in the 5-leaved perianth of the
♂-flower, the 5 stamens (Fig. 346–351) with filaments _erect_ in the
bud, and in the ♀-flower by the small, entire, cup-like perianth, which
surrounds the base of the ovary (Fig. 346, p. 352). The ovary has two
styles, or one divided into two, with two stigmas and a pendulous,
curved ovule (Fig. 346 _B_, 352 _B_); the fruit is a nut; the _embryo_
is _curved_ (Hemp, Fig. 353), or rolled (Hop, Fig. 349), _without
endosperm_.
[Illustration: FIG. 346.--Diagram of male and female flowers of
the Hop and Hemp: _b_ the bract, _p_ the perianth. The position
of the embryo is indicated.]
Only 2 genera with 3 species (Asiatic), of which two are
cultivated.--_Humulus lupulus_ (Hop, Figs. 347–349) is a twining,
perennial plant, twisting to the right, with opposite, palmilobed,
rough leaves, and large, interpetiolar stipules. The ♀-flowers are
situated in closely-flowered, cone-like, compound inflorescences, with
ultimately large, thin, imbricate floral-leaves (Fig. 348) which bear
the yellow, glandular hairs, containing lupulin. ~This inflorescence is
made up as follows:--The most external floral-leaves are situated in
pairs, and are the persistent stipules of a leaf, the blade of which
has become suppressed, or in any case is rudimentary. Such a pair of
stipules supports 4 (2–6) flowers in a double uniparous cyme, whose
central axis does not develope into a flower. The bracts of these
flowers (bracteoles of the partial inflorescence) become, at maturity,
very large, spathe-like, and, together with the stipules, produce a
cone-like appearance.~
[Illustration: FIG. 347–348.--_Humulus lupulus_: 347, twining
stem; 348, branch with strobiles.]
_Cannabis sativa_ (Hemp, Figs. 350–353) is an East Indian herb, with
palmilobed leaves, and differs from the Hop in being annual, erect,
and in having its leaves opposite at the base and scattered above.
The ♀-inflorescence is not cone-like as in the Hop, but the flowers
are similar in construction. ~The main difference is to be found in
the axillary shoot, which was suppressed in the Hop, and is in the
Hemp developed into a leaf-bearing shoot which on each side bears only
one ♀-flower, and in the fact that the bracts are not so strongly
developed.~
The “Hops” (the female inflorescences) are used in brewing,
and medicinally on account of the yellow glands which contain
lupulin. The Indian variety of _Cannabis sativa_ contains
an abundance of glandular hairs and resin. The withered
inflorescences are used in medicine and are officinal. The bast
of the stems of the Hemp is also used and the fat oil of the
seeds. In Oriental countries the entire plant is used in the
preparation of an intoxicating drink (haschisch), the narcotic
material being found in the glandular hairs.
[Illustration: FIG. 349.--_Humulus lupulus_: fruit in
longitudinal section.]
[Illustration: FIGS. 350–353.--_Cannabis sativa_:
Fig. 350, ♂-plant;
Fig. 351, ♂-flower;
Fig. 352, ♀-flower, entire and in longitudinal section;