646 
PHANEROGAMS. 
but sometimes it is less (as in Hypericum perforatum with three staminal bundles 
in the pentamerous flower) ; so that an increase in the number of stamens is 
united with a decrease of the typical number of staminal leaves. 
The branching of carpels is much less common than that of stamens. It 
occurs very clearly in Malvaceae, where the typical number of carpels is five, 
and they are often developed as such (as in Hibiscus). In some genera however 
(as Malva, Malope, and Althcea) five original rudiments of carpels first of all make 
their appearance in the form of a low cushion. Each of these forms very early 
a larger number of outgrowths lying side by side, and each of these produces a style 
and a one-seeded compartment of the peculiarly-shaped gynaeceum ^ 
This short sketch will be sufficient to show what variations are possible in 
the numbers and positions of the parts that may be included under the expression 
6",^ P.^j .S/« Cn which, as has already been said, is especially characteristic 
of flowers with pentamerous or truly tetramerous whorls. True tetramerous flowers 
are allied not only to those that are octamerous (like Michauxid), but also to 
those with dimerous whorls, among which (Enotherese may be especially men- 
tioned. Of genera belonging to this family, Epilohium, for example, is constructed 
on the formula S^^^ Py^^ St^^^ C^, Circcea on that of St^ C.^ ; and Trapa, with 
the formula S^^^ P^^ Si^ C^, must also be included here. Although in Epilobium 
and Trapa the calyx really consists of two whorls, this pseudo-whorl formed of 
two decussate pairs is followed by the other whorls exactly as if it were a true 
tetramerous whorl. But other dimerous and tetramerous flowers exhibit a more 
considerable deviation from the type, inasmuch as the two dimerous perianth-whorls 
which develope as if they were a tetramerous calyx or corolla are followed by a 
staminal whorl which is superposed on the pseudo-whorl consisting of two decussate 
pairs, as in Urtica and other genera of the order, and in Proteaceae with the 
formula S.^^^ St, Q (Fig. 370). 
Among the dimerous and trimerous flowers of the orders Polycarpae and 
Cruciflorae, where they are the most perfectly developed, a tendency prevails for 
more than one whorl to go to the formation of the calyx, the corofla, the androecium, 
and even the gynaeceum, a tendency which may be expressed by the formula 
Sp{+p+...)Pp{+p+...)Stp(^p^...)C^,(^p^...); for example. 
FIG. 461. — Diagram of Catidollea 
(Dilleniacese). 
Fig. 462. — Diagram of Citrus 
(Aurantiaceae). 
Fig, 463.— Diagram of Tiliaceae. 
Fumariacese, S^P^^.^St^j^... C^. 
Berberideae, 
Fpimedium, S^j^^P^^^St^,^^ 
1' 
^ See Payer, Organogenic de la fleur, PI, 6-8. 
