CUCURBITA 



583 



The primordia of the petals appear shortly after those of the 

 sepals and alternate with them. They form a cycle of five small, 

 blunt protuberances which at first grow less rapidly than the 

 sepal primordia; but later accelerate their growth and, like the 

 sepal lobes, form an enclosing protective envelope over the tip of 

 the receptacle. These primordia are also pubescent but the hairs 

 are less rigid than those on the sepals. The development of these 

 two cycles of primordia, 

 which ultimately become 

 the lobes of the calyx and 

 corolla respectively, is ac- 

 companied by the growth 

 of the undiverged tissues 

 immediately below them, 

 which results in the for- 

 mation of a continuous 

 cylinder of tissue consti- 

 tuting the perianth tube. 



One of the three rudi- 

 mentary stamens is smaller 

 than the other two, each 

 of which arises opposite a 

 petal lobe. The small one 

 is located in an interval 

 between a petal lobe and 



1,1 J ^u^ ^*,„^ Fig. ^04. ^, habit of pistillate flower ; B, median 



a sepal lobe and the spac- i^^^^J^-l^ 3howing epigynous character; C, longi- 



ing is such that the three section of staminate flower with abortive pistil ; D, 



are equidistant from one transection of tricarpellate ovary showing placen- 



T- . ration. 



another within the peri- 

 anth tube. They appear shortly after, or in some cases coincident 

 with, the origin of the petal primordia; the smallest staminodium 

 appealing first, and the second and third arising in a counter-clock- 

 wise direction. At first, the staminodia are conspicuous; but, as 

 the flower develops, their growth is arrested and their terminal 

 portions may become withered and dried. The continued growth 

 of the perianth tube, below the point of divergence of the stami- 

 nodia, gives them the appearance of diverging from a midpoint in 

 the perianth tube. 



Following the appearance of the staminodia, three small lobes 

 arise equidistant from one another at the bottom of the cavity of 



