The plants belonging to this family are almost exclusively herbaceous,
with scattered, exstipulate leaves. The flowers are eucyclic di- or
tetramerous, with the calyx and corolla deciduous, _hypogynous_,
☿, _regular_, the gynœceum with 2–several carpels (generally 2,
transversely placed) (Figs. 391, 392, 393, 397). The ovary is
_unilocular with parietal placentæ_, but in _Cruciferæ_ and a few
others it becomes bilocular by the development of a _false_, membranous
wall between the placentæ. The stigmas in the majority of cases
are _commissural_, _i.e._ they stand above the placentæ, and not
above the dorsal line of the carpels. The fruit is nearly always a
_capsule_, which opens by the middle portions of the carpels detaching
themselves as valves, bearing no seed, whilst the placentæ persist
as the seed-bearing frame. Endosperm is found in _Papaveraceæ_ and
_Fumariaceæ_, but is absent in _Cruciferæ_ and _Capparidaceæ_.--~This
family through the Papaveraceæ is related to the Polycarpicæ (the
Nymphæaceæ), through the Capparidaceæ to the Resedaceæ in the next
family.~
Exceptions to the above are: _Eschscholtzia_, _Subularia_ (Fig.
403) and a few Capparidaceæ, in which perigynous flowers are
found. A few Papaveraceæ and Fumariaceæ have trimerous flowers.
In _Fumaria_ and certain Cruciferæ, the fruit is a nut. The
Fumariaceæ have zygomorphic flowers. Trees and shrubs are almost
entirely confined to the Capparidaceæ, in which order stipules
also are found.
Order 1. =Papaveraceæ= (=Poppies=). Herbaceous plants with stiff hairs
and _latex_; flowers _regular_ (Fig. 391) with generally 2 (-3) sepals
(which _fall off_ as the flower opens), 2 + 2 petals (imbricate
and crumpled in the bud) _without spur, numerous stamens in several
alternating whorls_ (generally a multiple of 2); carpels 2–several,
united into a unilocular gynœceum. Trimerous flowers also occur.
Capsule with very numerous seeds on the parietal placentæ; embryo
small, with large, oleaginous _endosperm_ (Fig. 392).--The leaves have
no stipules and are generally pinnately lobed.
[Illustration: FIG. 391.--A Diagram of the flower of _Glaucium_
and the dichasium (which becomes transformed into a scorpioid
cyme). _B Papaver argemone_, transverse section of the ovary
with indication of the position of the stigmas.]
[Illustration: FIG. 392.--_Papaver somniferum_: _A_ capsule;
_st_ the stigma; _v_ valves; _h_ pores; _B_ seed in longitudinal
section; _alb_ endosperm; _emb_ embryo.]
_Papaver_ (Poppy) has large, solitary, terminal flowers; petals firmly
and irregularly folded in æstivation; gynœceum formed by many (4–15)
carpels; stigmas velvety, _sessile_ and _stellate_ (the rays stand
above the placentæ) (Fig. 391 _B_). The edges of the carpels project
deeply into the ovary, but do not meet in the centre, so that it
remains unilocular. The capsule opens by pores placed close beneath
the stigma, and formed of small valves alternating with the placentæ
and the rays of the stigma (Fig. 391). _P. dubium_, _P. argemone_, _P.
rhœas_.--_Chelidonium_ (Greater Celandine) has _yellow_ latex, flowers
in umbellate cymes (the terminal, central flower opening first) and
only 2 carpels; the fruit resembles the siliqua of the Cruciferæ in
having two _barren valves_, which are detached from the base upwards,
and a _seed-bearing frame_, but there is no partition wall formed
between the placentæ. _Ch. majus._--~The majority of the other genera
have, like _Chelidonium_, 2 carpels (lateral and alternating with the
sepals: Fig. 391 _A_) and siliqua-like fruit, thus: _Eschscholtzia_
(perigynous) with a linear, stigma-bearing prolongation extending as
far above the placentæ as above the dorsal suture of the carpels;
_Glaucium_ (Horn-Poppy); _G. luteum_, whose extremely long, thin
capsule differs from that of _Chelidonium_ by the formation, during
ripening, of a thick, spongy (_false_) replum, which persists when
the valves are detached; _Sanguinaria_ with red latex, the 2 petals
divided into 8–12 small petals (perhaps by dédoublement); _Macleya_ and
_Bocconia_ (1-seeded capsule) with 2 sepals and no petals.--Trimerous
flowers are found in _Argemone_ and _Platystemon_ (with a curious
fruit, carpels free, and transversely divided and constricted into
joints which separate as nut-like portions).--_Meconopsis._--_Hypecoum_
(Fig. 393 _C_) has tri-lobed and three cleft petals, 4 free stamens
with 4-locular anthers and a jointed siliqua; it presents a
transitional form to the Fumariaceæ, with which order it is sometimes
included.~
POLLINATION. _Papaver_ and _Chelidonium_ have no honey, and
are without doubt only visited by insects for the sake of
the pollen. The anthers and stigmas mature about the same
time.--There are 80 species; especially from warm climates.
OFFICINAL: _Papaver somniferum_ (Opium-Poppy); the latex
of its unripe capsules is obtained by incisions, and dried
(_opium_); it contains many alkaloids: morphine, papaverine,
narcotine, thebaine, etc. The oleaginous seeds are also used
in the manufacture of oil. Its home is in the East, where it
is extensively cultivated. The petals of the Corn-poppy (_P.
rhœas_) are also officinal. Several species are cultivated as
ornamental plants.
Order 2. =Fumariacæ= (=Fumitories=). This order differs from the
closely allied Papaveraceæ in the absence of latex, a poorer flower,
generally _transversely zygomorphic_ (Fig. 393 _B_), in which case one
or both of the outer lateral petals are gibbous, or prolonged into
a spur; the stamens are especially anomalous. Sepals =2=, caducous;
petals 2 + 2; stamens 2, _tripartite_; each lateral anther is
_bilocular_ (Figs. 393 _A_, _B_; 395); gynœceum bicarpellate. The fruit
is a nut or siliqua-like capsule. _Endosperm._--_Herbs_ with scattered,
repeatedly pinnately-divided leaves without stipules, generally quite
glabrous and glaucous; the flowers are arranged in racemes with
subtending bracts, but the bracteoles are sometimes suppressed.
_Dicentra_ (syn. _Dielytra_) and _Adlumia_ have a doubly symmetrical
flower, with a spur or gibbous swelling at the base of _each_ of
the laterally-placed petals (Figs. 393 _A_, 394). _Corydalis_ has a
zygomorphic flower, _only one of_ the lateral petals _having a spur_,
and consequently there is only one nectary at the base of the bundle of
stamens, which stands right in front of the spur (Fig. 393 _B_, 395,
396). The fruit is a many-seeded siliqua-like capsule. ~A peculiarity
of the flower is that the plane of symmetry passes _transversely_
through the flowers, whilst in nearly all other zygomorphic flowers
it lies in the median line. Moreover, the flower is turned, so that
the plane of symmetry ultimately becomes nearly vertical, and the spur
is directed backwards.--Many species have subterranean tubers; in
these the embryo germinates with _one cotyledon_, which is lanceolate
and resembles a foliage-leaf. The tuber is in some the swollen
hypocotyl (_C. cava_), in others a swollen root (_C. fabacea_, etc.),
which grows down through the precisely similar swollen root of the
mother-plant. The sub-genus _Ceratocapnos_ has dimorphic fruits (nuts
and capsules) in the same raceme.~ _Fumaria_ differs from _Corydalis_
only by its almost drupaceous, one-seeded nut (Fig. 395).
[Illustration: FIG. 393.--Diagram of _Dicentra_ (_A_),
_Corydalis_ (_B_), and _Hypecoum_ (_C_).]
[Illustration: FIG. 394.--_Dicentra spectabilis_: _A_ flower
(2/5); _B_ the same, after removal of half of one outer petal;
the cap, formed by the inner petals, is moved away from the
anthers and stigma; the insect does this with the lower side of
its abdomen, and thus rubs the stigma on the hairs of its ventral
surface; the dotted line at _e_ indicates the direction of the
proboscis; _C_ andrœcium and gynœceum; _D_ stigma.]
THE STRUCTURE OF THE FLOWER. _Hypecoum_ among the Papaveraceæ
is the connecting link with the Fumariaceæ. The diagram (Fig.
393 _C_) corresponds both in number and in the relative position
of its members with that of most of the other Papaveraceæ (Fig.
391), except that there are only four stamens (with extrorse
anthers). In _Dicentra_ (Fig. 393 _A_), the two central
(uppermost) stamens are absent, but each of the two lateral ones
are divided into three filaments, of which the central one bears
a four-locular anther, and each of the others a two-locular
(half) anther. _Corydalis_ and _Fumaria_ stand alone in the
symmetry of the flower, differing from _Dicentra_ in having only
one of the lateral petals (Fig. 393 _B_, _sp_) prolonged into
a spur, while in _Dicentra_ both the petals are spurred. This
structure has been interpreted in various ways. According to Asa
Gray the median stamens are absent in the last-named genera, and
the lateral ones are split in a similar manner to the petals of
_Hypecoum_. Another, and no doubt the most reasonable theory
(adduced by De Candolle), is: that two median stamens are split,
the two parts move laterally, each to their respective sides
and become united with the two lateral stamens; this affords a
natural explanation of the two half-anthers, and establishes a
close relationship to the Cruciferæ. A third interpretation,
held by Eichler and others, is as follows: the median stamens
are _always_ wanting; when they appear to be present, as in
_Hypecoum_, it is due to the fact that the side portions of
the lateral stamens _approach each other_ (as interpetiolar
stipules) and coalesce into an apparently single stamen.
[Illustration: FIG. 395.--_Fumaria officinalis_: _A_ the flower
in longitudinal section; _B_ the andrœcium and gynœceum; nectary
to the right.]
[Illustration: FIG. 396.--_Corydalis cava_: _a_ a flower (lateral
view); _b_ the anthers lying round the stigma; _c_ the anthers
shortly before the opening of the flower; _d_ the head of the
stigma; _e_ relative position of the parts of the flower during
the visit of an insect.]