280 OBSERVATIONS ON THE NATURAL FAMILY 



In conformity with this view of its composition, and with 

 the relation above attempted to be established, the deve- 

 lopment of the pistillum precedes that of the stamina in 

 many species of the genus. 



It is more difficult to determine whether this order of 

 expansion and relative position of sexes in Euphorbia be in 

 conformity with the general rule, or an exception to it. 

 For its fasciculus of flowers may be considered as analogous 

 either to the simple spike, and consequently having an 

 inverted order of expansion, as in Allium descendens, and 

 certain species of Grevillea and Anadenia .• or it may be 

 assimilated to the compound spike, as in several species of 

 the genus the male flowers appear to be separated into 

 100] fasciculi ; and according to this view the order of expan- 

 sion is direct, the central female flower being the repre- 

 sentative of the terminal partial spike. 



There is even a third species of inflorescence with which 

 the fasciculus of Euphorbia may be compared, namely, that 

 consisting of one or more verticilli with a single flower in 

 the centre. In this, which may be considered a modi- 

 fication of the spike or umbel, the usual order of expansion 

 seems to be from centre to circumference. Its simplest 

 form occurs in an unpublished New Holland genus of the 

 same natural family with Euphorbia, in which a single 

 verticillus of male flowers surrounds the central female 

 flower. Lamhertia may be considered as another instance 

 of the same mode, and as far as can be determined, in a 

 case where the flowers are hermaphrodite and their ex- 

 pansion nearly synchronous, following the same order. In 

 all the known species of this genus the leaves are verticil- 

 late, and uniformly in threes : in L. formosa and inermis 

 the involucrum constantly contains seven flowers, while in 

 L. uniflora it is reduced to one flower. The seven flowers 

 of the two former species I consider as made up of two 

 verticilli, in number of flowers corresponding with that of 

 the leaves, and of a single central or terminal flower ; to 

 which terminal flower L. uniflora appears to be reduced. 

 Prom this order of reduction it may be assumed as more 

 probable that species of Lambertia should be found with 



