DICOTYLEDONS. 
647 
'ben's, S^j^.^P^j^^Sl^j^^C^, 
Podophylluni, Pz+^ ^^z+z 
Cruciferas, ^'2+2 Q+2)- 
A large number of examples of this general formula are afforded by the 
family Menispermaceae, in which the whorls are sometimes dimerous, sometimes 
trimerous, while sometimes whorls of each description occur in one flower ; and 
where almost every one of the organs may disappear by abortion ^ 
In addition to the trimerous flowers already mentioned, there are also some 
which come under the first-mentioned general formula ^4(+h) j 
for example, Rheiim with the formula -^'^Vs ^s- Other trimerous flowers 
again appear to belong to a third type, as Asarum with the formula St^^^ Q. 
When the number of staminal whorls is considerably increased, it not unfre- 
quently happens that the number of stamens in each whorl also undergoes change, 
and complicated alternations arise. Flowers the structure of which is otherwise 
altogether different resemble one another in this respect, as is shown by the 
Papaveraceae on the one hand (Fig. 464), and by the Cistineae and some Rosaceae 
on the other hand. 
Fig. 464.— Diagram of Papaveracese ; A Chelidoniwn, a Papaver. 
The reduction of the flower to a simpler condition is often carried so far 
in many Dicotyledons (as in Monocotyledons) that each individual flower consists 
only either of an ovary with one or several stamens, or, when the arrangement 
is diclinous, even only of a single ovary or of a single or several stamens; the 
perianth being either entirely absent (as in Salix and Piperaceae) or reduced to a 
cup-like structure {Populus, the female flower of Cannabineae, &c.) or to hair-like 
scales among the sexual organs which represent the flower (e.g. Plaianus). Flowers 
of this kind are generally very small and densely crowded in large numbers in 
the inflorescence (such as capitula, spikes, or catkins). In some cases it may even 
be doubtful whether we have an inflorescence or a single flower, as in the genus 
Euphorbia ^. 
The development of the separate parts and the entire form of the flower 
in the mature state is so various that it is scarcely possible to state any general 
^ Eichler, Ueber die Menispermaceen, Denkschrift der k. bayer. Ges., Regensburg 1&Ö4. — 
Payer, Organogenie de la fleur, PL 45-49. — Eichler, Flora, 1865, Nos. 2-8 et seq. 
^ See Payer, I.e. p. 529; [also foot-note to p. 490. It is now generally admitted that the 
Cyathium of Euphorbia is an inflorescence, a view which was first enunciated by Robert Brown in 
opposition to Linnoeus, who regarded it as a single flower. It appears that the stamens are here 
axial (Warming, Ueb. pollenbildende Caulome und Phyllome, in Hanstein's Bot. Abhdl. II, 1S73)]. 
