_Euphorbia_ (Spurge) has the most reduced flowers, which are borne
in a very complicated inflorescence. Each ♂-flower (Fig. 460 _B_) is
naked, and consists of one stamen only (terminal on the axis). In the
closely allied genus _Anthostema_, a small perianth is situated at
the place where, in _Euphorbia_, there is a joint in the “filament,”
(Fig. 461 _A_). The ♀-flowers (Fig. 460) are naked, with a 3-locular
ovary and 3 bifid styles. (_Anthostema_ has a distinct perianth (Fig.
461 _B_); in a few Euphorbias traces of a perianth are present).
In _Euphorbia_ the ♂-and ♀-flowers are grouped into flower-like
inflorescences termed “cyathia.” Each cyathium consists of a centrally
placed ♀-flower which is first developed, surrounded by 5 groups of
♂-flowers (stamens) placed in a zig-zag, with a centrifugal order
of development (Figs. 459, 460 _B_), that is, in unipared scorpioid
cymes; these flowers are surrounded by an _involucre_ of 5 leaves
united into a _bell-shaped structure_ (Fig. 459, 1–5) (resembling a
calyx); on its edge are placed 4, generally crescent-like, yellow
glands, one in each of the intervals, except one, between the lobes of
the involucre (shaded in Fig. 459; see also Fig. 460 _A_). Scale-like
thin structures (floral-leaves?) are situated between the ♂-flowers.
The ♀-flower has a long stalk, and finally bends down on one side,
namely to the place on the edge of the involucre where the gland is not
developed. These cyathia are again arranged in an inflorescence which
commences as a 3–5-rayed umbellate cyme (pleiochasium), the branches
of which ramify dichasially and finally as scorpioid cymes.--Latex,
with peculiar-shaped starch-grains, is found in laticiferous _cells_
(especially in the Cactus-like, leafless species.)
[Illustration: FIG. 459.--Diagram of an inflorescence (cyathium)
of _Euphorbia_ with 3 floral-leaves, _m_, _n_, _o_, supporting
other cyathia which are subtended by 2 floral-leaves (bracteoles;
_m_, _n_). 1–5, the involucral leaves in their order of
development; the shaded portions are the crescentic glands.]
[Illustration: FIG. 460.--_Euphorbia lathyris_: _A_ an (entire)
inflorescence (cyathium); _B_ the same after the removal of the
involucre.]
[Illustration: FIG. 461.--_Anthostema_: ♂- (_A_) and ♀-(_B_)
flowers; _p_ the perianth; _ar_ the node; _o_ the ovule.]
205 genera; more than 3,000 species; especially in the
Tropics.--Many are used on account of the oil, and of the
pungent (aperient, poisonous, anthelmintic, etc.) properties in
the latex or the seeds. OFFICINAL: “Cascarilla-bark” of _Croton
eluteria_; the fatty oil of the seeds of _Croton tiglium_
(Trop. Asia); “Castor oil” from _Ricinus communis_ (Africa,
and cultivated in all warm climates throughout the world);
the glandular hairs of _Mallotus philippinensis_ (“Kamala”);
this also yields a red dye. Gum “Euphorbium” is the hardened
(resinous) latex of the _Cactus_-like _Euphorbia resinifera_
(Morocco).--NUTRITIVE plants: _Manihot utilissima_ and other
species (Maniok, Am.). Their large, farinaceous roots form a
very important article of food in the Tropics (Cassava-flour,
Tapioca or Brazilian arrowroot). The fresh latex of the root in
some species is a powerful poison; but the poisonous properties
are diminished by roasting or cooking. _Caoutchouc_ is obtained
from _Siphonia elastica_ (Trop. S. Am.). The vegetable
tallow of the Chinese tallow-tree (_Stillingia sebifera_) is
used in large quantities in soap factories. An indigo-like
_dye_ is obtained from _Crozophora tinctoria_, and is also
found in _Mercurialis perennis_. Shellac is obtained from
_Aleurites laccifera_. ORNAMENTAL plants: _Acalypha_, _Croton_,
_Dalechampia_.--_Hippomane_ is poisonous.
Order 2. =Buxaceæ.= This order differs from the Euphorbiaceæ
in having the micropyle turned inwards; the ♂-flower has a
4-partite perianth and 4 stamens; the ♀-flower a 6-partite
perianth and 3 carpels. Capsule with loculicidal dehiscence,
the inner layer being detached elastically from the outer.--30
species. Shrubs without latex and with evergreen leaves.--_Buxus
sempervirens_ (Box) is an ornamental shrub (poisonous); it has a
very hard and valuable wood which is used for wood-engraving and
carving.
[Illustration: FIGS. 462–464. _Callitriche stagnalis._
FIG. 462.--♂-flower with the 2 bracteoles and the solitary stamen.
FIG. 463.--♀-flower.