This family resembles the Quercifloræ in the catkin-like
inflorescences, the imperfect, _unisexual_ flowers, the epigynous
perianth and the woody shoots with scattered leaves, etc., though it
is in other respects very dissimilar; one point of difference is the
presence of _aromatic_ compounds, but a more important divergence is
found in the structure of the gynœceum, which is formed of two carpels
with _one loculus_ and has one _basal_, _orthotropous and erect_
ovule, which, as in the Quercifloræ, does not become developed until
after pollination; the fruit too is very different, being generally a
_drupe_. _Endosperm absent._
[Illustration: FIG. 337.--_Juglans regia_: _A_ ♂-flower seen
from below with bract (cover-scale) (_b_), bracteoles (α and β),
perianth-leaves (_p_); _B_ the same from the front; _C_ lateral
view of the same; _D_ diagram of _A_; _E_ ♀-flower with bract,
the bracteoles are united with the ovary, their edge being
visible as an indented line below the perianth; _F_ 2 ♀-flowers
at the end of a foliage-shoot; _G_ fruit (without the fleshy
covering) in longitudinal section; _H_ transverse section of the
same.]
Order 1. =Juglandaceæ (Walnuts).= Leaves _scattered_, _imparipinnate_,
rich in _aromatic_ compounds. _Stipules absent._ Flowers unisexual.
_Monœcious._ The ♂-catkins are lateral, generally on naked branches
of the previous year, cylindrical, pendulous, many-flowered; the two
bracteoles and the 2–4-leaved perianth of the ♂-flower unite with
the subtending bract; the ♂-flower has indefinite stamens (6–20 in
_Juglans_, Fig. 337 _A-D_). The ♀-catkins are terminal, generally on
branches of the same year, few-flowered (Fig. 337 _F_); the ♀-flowers
have a _superior_, 4-leaved perianth, a bicarpellate gynœceum, two
styles with stigmas on the internal surface. The ovary, bracteoles
and bract all unite together (Fig. 337 _E_). The fruit is generally a
green or black _drupe_,[34] whose flesh (outer soft portion) in _Carya_
and _Juglans_ ruptures more or less irregularly, and frees the stone
(“Walnut”).--~The stone in _Juglans_ is divided internally by one true
(Fig. 337 _H_) and by several false, low partition walls into several
_incomplete_ compartments, so that the two large _cotyledons_ become
lobed and incised to fit like a cast into the irregularities of the
inner surface of the stone; the embryo is exendospermous and covered
with a thin testa.--THE LEAF SCARS are large and cordate with 3 groups
of vascular bundles. The PITH in _Juglans_ and _Pterocarya_ is divided
into chambers. The stone ruptures, on germination, along the dorsal
suture into 2 valves; the cotyledons remain underground. In _Juglans
regia_ a long row of accessory buds is found on the lowest internode
(epicotyl) above the axils of the cotyledons. _Pollination by the
wind._ Both protogynous and protandrous examples of _Juglans regia_
occur.--33 species, mostly in temperate North America.--USES. Walnuts
are obtained from _J. nigra_ and _regia_; Hickory from North American
species of _Carya_. The oil-containing seeds of several species are
edible. _Pterocarya_ and others are cultivated as ornamental plants.~
[Illustration: FIG. 338.--_Myrica gale_: _a_ young fruit; × the
bracteoles with numerous glands; _b_ longitudinal section of
fruit.]
Order 2. =Myricaceæ=. To this order belong shrubs or trees which
have penninerved, simple, at most lobed or pinnatifid leaves, with
or without stipules, and with yellow, aromatic, resin glands (Fig.
338 _a_). The flowers, situated in catkin-like spikes, are unisexual
and _naked_, and supported by scale-like floral-leaves. ♂-flower: 4–6
(–16) stamens with short filaments; ♀: generally situated singly. The
gynœceum has a short style with 2 long stigmas, and unites with the
bracteoles, which form wing-like outgrowths on the ripe drupe as in
_Pterocarya_ in the Juglandaceæ (Fig. 338). Cotyledons fleshy (Fig. 338
_b_).--_Myrica_; _Comptonia_.
40 species; Temperate.--_Myrica gale_ (Sweet-gale, Bog-myrtle)
has been used in the preparation of beer (Sweet-willow beer)
on account of its resinous essential oil. _M. cerifera_ (N.
America) and species from the Cape, _M. quercifolia_ and others,
form wax on the fruit which is used in the preparation of
candles.