2. HESPERIDEÆ. Stigma strongly developed above the placenta;
style undivided or prolonged above the placentæ into
shorter or longer lobes.
_a._ Surface cells of the replum, not divided
diagonally.--_Capsellinæ_; _Turritinæ_;
_Erysiminæ_; _Alyssinæ_.
_b._ Surface cells of the replum divided
diagonally.--_Malcolmiinæ_; _Hesperidinæ_;
_Moricandiinæ_.]
[Illustration: FIG. 412.--_Isatis tinctoria._ Fruit (Fig. 412);
and in longitudinal section (Fig. 413). (Mag.)]
POLLINATION. Honey is secreted by the nectaries mentioned
above; but the position of the stamens is not always the most
favourable for pollination by insects (in these flowers the
honey-seeking insect must touch the anthers with one of its
sides and the stigma with the other), and self-fertilisation
is common. In some species (_Cardamine pratensis_) the long
stamens turn their anthers outwards towards the small stamens,
so that 3 anthers surround each of the two large entrances to
the nectaries.
1200 species (180 genera), especially in the cold and
temperate parts of the Old World (Europe, W. Asia). Many
are _weeds_ in this country, _e.g._ Wild Cabbage (_Brassica
campestris_), Charlock (_Sinapis arvensis_), Wild Radish
(_Raphanus raphanistrum_) and others.--The order is acrid and
oleaginous. Oil is obtained from many of the oil-containing
seeds, especially of the Rape (_Brassica napus_), Summer-Rape
(the oil-yielding cultivated form of the Field-Cabbage) and
_Camelina_. Several are pot-herbs or fodder plants, _e.g._
Cabbage
(_Brassica oleracea_) with its numerous varieties: Cauliflower
(var. _botrytis_; the entire inflorescence is abnormally
branched and fleshy), Kohlrabi (var. _gongylodes_, with
swollen, tuberous stem), Kale, Red-Cabbage, White-Cabbage,
etc.; _B. campestris_, var. _rapifera_ (Turnip); _B. napus_,
var. _rapifera_ (Swede); _Raphanus sativus_ (Radish from W.
Asia), _R. caudatus_ (long Radish); _Nasturtium officinale_
(Water Cress), _Lepidium sativum_ (Garden Cress), and _Barbarea
præcox_ (Early Cress); _Crambe maritima_ (Sea-Kkale). The
seeds of the following are especially used as spices: (the
flour of) _Melanosinapis_ (Black-mustard), and _Sinapis
alba_ (White-mustard), which are _officinal_ like the root
of _Cochlearia armoracia_ (Horse-radish, E. Eur.). The
herbaceous parts of _Cochlearia officinalis_ and _danica_
are medicinal.--A blue dye (woad) is extracted from
_Isatis_.--Ornamental plants: _Cheiranthus cheiri_ (Wallflower),
_Matthiola_ (Stock), _Iberis_, _Hesperis_, _Lunaria_, and others
(especially from S. Eur.). Sweet-scented flowers are rare.
[Illustration: FIG. 414.--_Gynandropsis pentaphylla._]
[Illustration: FIG. 415.--_Capparis spinosa._]
Order 4. =Capparidaceæ= (=Capers=). The relationship with the
Cruciferæ is so close that certain forms are with difficulty
distinguished from them. The diagram of the flower is the same
in the number and position of its parts, but it differs in the
modifications which occur in the development of the stamens. In
some genera all 4 stamens are undivided; in others both the 2
median ones are divided as in the Cruciferæ (6 stamens, but _not
tetradynamous_) (Fig. 414); in other genera only 1 of these; in
other instances again they are divided into more than 2; and
finally the 2 lateral ones also may be found divided, so that
_indefinite stamens_ occur (Fig. 415). The bicarpellate gynœceum
is _unilocular_ (without replum), but more than 2 carpels may
occur. The ovary is elevated on a _stalk_ (sometimes as much
as 1 foot in length); also between the stamens and corolla a
similar stalk may be found (Fig. 414). The fruit is long and
siliquose (_Cleome_, _Polanisia_, _Gynandropsis_), or a berry
(_Capparis_). Endosperm absent. Some have zygomorphic flowers.
Gamosepalous calyx and perigynous flowers also occur.--350
species; especially in the Tropics. The majority are trees
and shrubs, and they differ also from the Cruciferæ in having
distinct stipules present in some species.
“Capers” are the flower buds of the climbing, thorny shrub,
_Capparis spinosa_ (Fig. 415), which grows in the Mediterranean.