The four orders differ from one another partly in the arrangement of
the leaves (_Cupressaceæ_ have opposite or verticillately placed
leaves, flowers, and inflorescences; in the others they are placed
spirally), but chiefly in the greater or less degree of union which
takes place between the female flower (the leaf-like “symphyllodium”)
and its supporting cover-scale, and in the position of the ovules (the
micropyle being turned upwards or downwards). The “cone-scales” in
_Abietaceæ_ are formed by “symphyllodia” alone, in the others by
their union with the cover-scale.
Order 1. =Araucariaceæ.= This order most frequently has _solitary_
ovules, _turned downwards_ and attached _to the centre_ of the
cone-scales. In _Agathis_ (_Dammara_) the arrangement is the most
simple, a winged seed (Fig. 265), which hangs _freely_ downwards, being
borne in the centre of the undivided cone-scale. In _Araucaria_, the
stamens with the _free, pendulous_ pollen-sacs have been represented
in Fig. 242; the ovuliferous scale is united for nearly its whole
length with the bract, and projects from its apex in the shape of a
sheath-like, dentate scale, resembling the ligule in _Isoëtes_, and may
therefore be termed a “ligule.” _Araucaria_ (S. America, Australia) has
often rather broad leaves (_A. brasiliensis_). The ovuliferous scale in
_Cunninghamia_ is more distinct, and stretches transversely over the
entire cover-scale; it bears three inverted ovules (Fig. 266) (Eastern
Asia).
[Illustration: FIG. 265.--_Agathis (Dammara) australis._
Cone-scale with the seed. _A_ Longitudinal section; _A’_ from
within; _fv_, _fv’_ vascular bundles; _v_ wing.]
[Illustration: FIG. 266.--_Cunninghamia sinensis._ Cone-scale
with three ovules, interior view: _d_ cover-scale; _f_
ovuliferous scale.]
[Illustration: FIG. 267.--_A-G Pseudotsuga douglasii_: _A_
cone, _B_ cone-scale, with the inner side turned forward; the
points of the cover-scale are seen behind it; _C-G_ transitions
from the acicular leaf to the cover scale, from the base of a
♀ cone. _H Pinus montana._ Young ovuliferous scale, with the
inner side turned forward; the ovules are now in the stage for
pollination. _J-M Abies alba_: _J_ male cone; _b_ bud-scale;
_a_ anthers; _K L M_ individual anthers.--_Pinus montana_: _N_
pollen-grain; the two lateral expansions are the air-bladders; in
the upper part of the interior of the grain a vegetative cell may
be seen, and in the centre the large cell-nucleus.]
Dammara-resin, which is used for varnish, is obtained from
_Agathis_ (_Dammara_) species (New Zealand, Philippine
Islands).
Order 2. =Abietaceæ (Pine and Fir Trees).= The leaves are spirally
arranged and needle-like. The flowers are _monœcious_. The male flowers
are long, and catkin-like, with numerous stamens, each bearing two
_oblong pollen-sacs_. The pollen-grains are most frequently tri-lobed,
having two bladder-like appendages, formed as outgrowths of the
exospore, to assist in their distribution by the wind (Fig. 267 _N_).
The bracts are arranged spirally. The union between the bract and the
ovuliferous scale, which is found in the preceding order, is not in
this instance so complete; these scales make their appearance as two
free parts, and are attached only at their bases (Fig. 268); the lower
portion, that is the cover-scale, in most instances remains quite
small (Fir, Red Pine, and others), it is only in the “Noble Pine”
(_Abies_) and _Pseudotsuga douglasii_, that it attains a greater length
than the ovuliferous scale (Fig. 267, _B-G_). On the other hand the
upper part, _the ovuliferous scale_ (the vascular bundles of which have
the bast turned upwards), grows strongly and elongates, especially
after fertilisation, becoming woody or leathery; it is commonly termed
the “_cone-scale_,” but is in reality only homologous with a part of
the “cone-scale” in the other order of Pinoideæ. On the side of the
ovuliferous scale, turned towards the axis, are situated _two ovules_
with micropyles _directed inwards_. The seeds are most frequently
provided with _a false wing_ (a tissue-like part of the surface of
the ovuliferous scale). Cotyledons, _more than_ 2, _verticillate_.
_Fertilisation does not take place until some time after pollination._
In _Pinus_, for instance, the pollen-tube only penetrates the nucellus
for a short distance during the year of pollination, and then ceases
its further growth, fertilisation not taking place until after the
middle of the next year; whilst the seeds ripen about a year and a half
after pollination. In the Larch and others, the seeds are mature in the
autumn succeeding pollination.
[Illustration: FIG. 268.--_A Abies_: _c_ the cover-scale;
_s_ ovuliferous scale, or “cone-scale”; _sk_ ovules in a young
condition. _B Pinus_: ovuliferous scale with two ovules (_s_);
_m_ the two-lobed micropyle; _c_ “mucro”; _b_ the cover-scale
behind. _C Abies_: ripe “cone-scale” with two seeds (_sa_); _f_
wing of seed.]
_Abies_ (Fir). The leaves are often (_e.g. Ab. pectinata_) displaced
into 2 rows, flat and indented at the apex, with 2 white (wax-covered)
lines on the under surface, in which the stomata are situated. The
leaf-scars are nearly circular and do not project. The cones are erect.
_The cover-scales and the ovuliferous scales separate from the axis_,
to which they remain attached in other genera.--~_Tsuga_ has leaves
like _Abies_, but by the slightly projecting leaf-scars, and cones with
persistent scales, it forms the transition to _Picea_.--_Pseudotsuga_
has leaves similar to those of _Abies_ and persistent carpels as in
_Picea_, but the cover-scales grow as in _Abies_ and project beyond
the ovuliferous scales (_P. douglasii_, Fig. 267). These two genera
are considered as sub-genera of _Abies_.~--_Picea_. The leaves project
on all sides, square and pointed; the leaf-scars are rhombic, on
projecting leaf-cushions. The cones are pendulous. The cover-scales are
much shorter than the leathery, persisting ovuliferous scales.--The
genus _Larix_ (Larch) differs from all the others in having deciduous
leaves (the three preceding have leaves which persist for eleven to
twelve years). It has _long-branches_ with linear foliage-leaves and
short, thick, _perennial dwarf-branches_, which each year form a new
rosette of foliage-leaves, similar to those on the long-branches. The
male flowers and the erect cones resemble those of _Picea_, and are
borne on dwarf-branches.--_Cedrus_ (Cedar) resembles _Larix_ to some
extent, but has persistent leaves (_C. libani_, _C. deodara_).--_Pinus_
(Pine) has long-branches and dwarf-branches. The leaves of the
long-branches are scale-like and not green; the dwarf-branches have
very limited growth, and persist for three years; they arise in the
axils of the scales borne on the long-branches of the self-same year,
and each bears 2–5 foliage-leaves, they are also surrounded at the base
by a number of membranous bud-scales. The cone-scales have a _thick,
rhomboid extremity_ (the “shield”).
The buds which develope into long-branches arise at the apex of
other long-branches, and being very close together, form false
whorls. The female cones occupy the position of long-branches,
and take about two years for their development. The male flowers
arise close together, and form a spike-like inflorescence at
the base of a long-branch of the same year. The male flowers
occupy the position of dwarf-branches, so that a female cone
may be considered to be a modified long-branch, and a male cone
a modified dwarf-branch. The main axis of the seedling has
needle-like leaves, similar to those found on the older parts,
and on dwarf-branches; it is not until some time later that
the dwarf-branches are developed and the permanent arrangement
attained.
USES. Several species are commonly cultivated in this country,
partly on heaths and moors, and partly in plantations and as
ornamental trees, such as Mountain Pine (_Pinus montana_, Cen.
Eur.); Austrian Pine (_P. laricio_, Eur.); Scotch Fir (_P.
silvestris_, Eur.); Weymouth Pine (_P. strobus_, N. Am.); common
Red Pine (_Picea excelsa_, Cen. and N. Eur.); White Pine (_P.
alba_, N. Am.); _Abies pectinata_ (Common Fir, S. and Cen. Eur);
_A. nordmanniana_ (Crimea, Caucasus); _A. balsamea_ (N. Am.);
_Tsuga canadensis_ (N. Am.); _Pseudotsuga douglasii_ (N.W. Am.);
Larch (_Larix europæa_, Alps, Carpathians); _L. sibirica_ (N.E.
Russia, Siberia).--The wood of many species, especially Pine,
on account of its lightness and because it is so easily worked,
is very well adapted for many useful purposes. The wood of the
Yew-tree is very hard and is used for ornamental turning. Resin
and Turpentine (_i.e._ Resin with essential oils, the name being
derived from the Terebinth-tree, from which formerly a similar
material was obtained) are extracted from _Pinus laricio_ and
_P. pinaster_. Oil of Turpentine is obtained by distillation of
turpentine with water; Tar by dry distillation of Pine-wood.
Canada-balsam is from North American _Abies_-species (_A.
balsamea_ and _Fraseri_). The officinal Turpentine is mainly
obtained from _Pinus pinaster_ (South of France), _P. tæda_,
_australis_, _strobus_ (Weymouth Pine) and other North American
species; more recently also from _P. silvestris_ (Scotch Fir),
_maritima_, _laricio_, _Picea excelsa_, and others; Venetian
Turpentine, from Larch (S. Eur.) Amber is resin from a Tertiary
plant (_Pityoxylon succiniferum_), closely related to the Pine,
which grew especially in the countries round the South-East
coast of the Baltic. _Pinus pinea_ (the Pine, S. Eur.) has
edible seeds and also _P. cembra_ (in Cen. Eur. and Siberia).
Order 3. =Taxodiaceæ.= The vegetative leaves and cone-scales are
arranged spirally. The ovules (2–9) are situated either at the base
of the ovuliferous scales, in which case they are erect; or at their
centre, when they are generally more or less inverted. The ovuliferous
scale is more or less united with the cover-scale, and projects
beyond the surface of the cone-scale, like a comb (Fig. 269). The
vascular bundles, which extend into the cover-scale, have the usual
leaf-arrangement, viz. the wood placed above the bast; while those
bundles which enter the ovuliferous scale have this arrangement of the
bundles reversed.
[Illustration: FIG. 269.--_Cryptomeria japonica._ Portion of
longitudinal section through female flower. _d_ cover-scale;
_f_ ovuliferous scale; _ov_ ovules; _fv_ and _fv’_ vascular
bundles; the xylem is indicated by a wavy line, and the phlœm by
a straight line.]
_Taxodium distichum_ (the North American “Swamp Cypress”) has
annual dwarf-branches, with distichous leaves, and cone-like
“pneumathodia.” In the Tertiary period it was very common in
the Polar regions. _Sequoia (Wellingtonia) gigantea_ is the
famous Californian Giant-Fir, or Mammoth-Tree, which attains
a height of 300 feet, a diameter of 36 feet, and is said to
live for 1,500 years. _Cryptomeria japonica_ (Japan, China) has
the least adnate ovuliferous scales; _Glyptostrobus_ (China);
_Arthrotaxis_ (Tasmania); _Sciadopitys verticillata_ (the only
species in Japan) has, like _Pinus_, scale-like leaves on
the long-branches, of which those which are situated at the
apex of the annual shoots support “double needles,” _i.e._
_dwarf-branches_ similar to the two-leaved dwarf-branches in
_Pinus_, but without bud-scales, and with the two leaves fused
together at the edges into one needle, which turns its upper
surface away from the long-branch.
Order 4. =Cupressaceæ= (=Cypresses=). _The leaves are opposite or
verticillate_, sometimes acicular, but most frequently scale-like
(Fig. 270). In the species with scale-like leaves, the seedlings
often commence with acicular leaves (Fig. 272), and branches are
sometimes found on the older plants which revert to this form, seeming
to indicate that the acicular leaf was the original form (atavism).
The so-called “_Retinospora_” species are seedling-forms of _Biota_,
_Thuja_, _Chamæcyparis_, which have been propagated by cuttings, and
retain the seedling-form. The flowers are monœcious or diœcious. The
male flowers are short, and have shield-like stamens, bearing most
frequently several pollen-sacs. The cover-scales and ovuliferous scales
are entirely fused together and form _undivided_ cone-scales, _opposite
or whorled_; _the ovuliferous scales_ have slight projections near _the
base_ on which 1–2–several _erect ovules_ are developed (Fig. 274).
Most frequently 2 cotyledons.--_Evergreen_ trees and shrubs.
[Illustration: FIG. 270.--_Cupressus goveniana._]
[Illustration: FIG. 271.--Portion of a branch of _Thuja
orientalis_ (magnified). The leaf at the base on the right has a
branch in its axil.]
[Illustration: FIG. 272.--Seedling of _Thuja occidentalis_. The
branch (_g_) is borne in the axil of the leaf _s_.]
_Juniperus_ (Juniper). _Diœcious._ The cone-scales become fleshy and
fuse together to form most frequently a 1–3 seeded “berry-cone.”
~_J. communis_ (Common Juniper) has acicular leaves, borne in whorls
of three, and the “berry-cone” is formed by a trimerous whorl
of cone-scales (Fig. 273). _J. sabina_ and _J. virginiana_ have
“berry-cones” formed from several dimerous whorls of cone-scales; the
leaves are connate and opposite, needle-and scale-like leaves are found
on the same plant.~
_Cupressus_ (Cypress). _Monœcious._ The cones are spherical; the
cone-scales shield-like, generally five-cornered and woody (Fig. 270),
each having many seeds. The leaves are scale-like.--_Thuja. Monœcious._
Cones oblong. The cone-scales are dry, as in the Cypress, but leathery
and imbricate, and not shield-like; each cone-scale bears 2–3 seeds.
The leaves are most frequently dimorphic; those leaves which are
situated on the edges of the flat branches are compressed, and only
these bear buds, which are developed with great regularity, generally
alternately, on both sides of the branch; those which are situated
on the flattened surfaces are pressed flat and broad, and never bear
branches (Fig. 271). Along the central line of each leaf there is a
resin-canal (Fig. 271).--~_Chamæcyparis_, _Callitris_, _Libocedrus_,
_Thujopsis_ (1 species: _T. dolabrata_; in Japan).~
[Illustration: FIG. 273.--Branch of Juniper with “berry-cones.”]
[Illustration: FIG. 274.--_Cupressus lawsoniana._ Longitudinal
section through female cone. Two ovules (_ov_) are bisected; _f_
ovuliferous scales.]
OFFICINAL. _Juniperus sabina_ from Central and South of Europe
(the young branches yield an essential oil). The wood of _J.
communis_ is used in the production of an essential oil, and
_J. oxycedrus_ in the production of empyreumatic oil. The
“berry-cone” of _J. communis_ is officinal, and is also used
for gin.--The wood of _J. virginiana_ (N. Am.) is known as red
cedar, and is used for lead-pencils. Sandarack resin is obtained
from _Callitris quadrivalvis_ (N.W. Africa).
THE FOLLOWING ARE CULTIVATED IN GARDENS:--_Thuja occidentalis_
(Arbor vitæ) (N. Am.), and _orientalis_ (China, Japan);
_Juniperus sabina_ and _virginiana_; _Thujopsis dolabrata_
(Japan); _Cupressus lawsoniana_ (California), _C. sempervirens_
(S. Eur., W. Asia), and other species, are grown especially
in conservatories, and in Southern Europe particularly in
cemeteries.--The _Retinospora_ species which are so often
planted, do not belong to an independent genus, but are obtained
from cuttings, taken from seedling-plants with acicular leaves
(see page 267).