EUPHORBIACE^ 



117 



volucre (?'«) formed by the union of five bracts IJjr) which 

 collectively surround a number of flowers. At the points of 

 junction of four of these bracts are four crescent-shaped 

 nectaries («), often described as glands. Within the involucre a 



cLn 



Fig. 147. — Vertical section of cyathium o^ Euphorbia pectus. 



number of stamens (a, an, an) and small scales {sc) appear to be 

 ranged round a long-stalked three-lobed ovary (pv). Staminate 

 flower (fig. 148) : each apparent stamen is really a naked stamin- 

 ate flower consisting of only one stamen situated on a flower- 

 stalk. A joint in the stalk of the stamen represents the point 

 at which the filament is inserted on the flower- 

 stalk. The part below the joint is the flower-stalk 

 {st\ and the portion above is the stamen with a 

 filament (/). [In a plant which is closely related 

 to Euphorbia there is a little perianth at the joint.] 

 The floral formula is KO CO Al GO. These 

 stamen-like flowers are arranged in five lines 

 oppositethe five bracts* (figs. 149, 150). Each of 

 these radial lines of staminate flowers represents 

 an inflorescence standing in the axil of a bract 

 (diagram 149). Carpellary flower (figs. 146, 147) : 

 the single central gynaecium with its long stalk oj Euphorbia 

 represents a simple naked nower composed or adjoining scale 

 three carpels. In some, spurges there is a distinct ^■'^^■ 

 hypogynous perianth, consisting of three or six perianth-leaves ; 

 even in the Petty Spurge there is a trace of this perianth (j>e). 

 The ovary {ov) is three-lobed and three-chambered, with one 



* This is more clearly seen in a large cyathium like that of Euphorbia 

 lathyris. 



staminate iiower 



