132 MORPHOLOGY OF THE ANGIOSPERMS 



curring in the primordia. (It is doubtful whether this is true dedouble- 

 ment, and it should be studied further.) The extent to which forking or 

 doubling represents true division, rather than fusion, can be determined 

 only by comparison with related taxa and by anatomical study. (Double 

 flowers have been said to be formed by the ontogenetic splitting and 

 transformation of stamens and carpels.) 



The stamen of Ricinus, massive, with many branches, each bearing a 

 terminal "anther," has been used as a branched type (Fig. 44). But this 

 interpretation is doubtless incorrect. The natine of this stamen can 

 probably best be determined by comparative studies of inflorescences 

 and flowers throughout the Euphorbiaceae, a family with many "flowers" 

 of difficult interpretation. The staminate flower of Euphorbia has been 

 reduced to a single stamen (Fig. 36A). The stamen of Ricinus is per- 

 haps an inflorescence. 



Support for the theory of telomic organization of the sporophylls of 

 angiosperms has been seen in what seems to be dichotomy of the 

 branches of the stamen of Ricinus. The tips of the branchlets show an 

 apparent dichotomous forking, with each branch terminated by a 

 sporangium. But the several varieties of the castor bean show that each 

 ultimate dichotomy represents an anther with the two anther sacs 

 nearly free from the connective, which is scalelike and often deciduous 

 (Fig. 44). 



The nature of fasciculate or clustered stamens was early discussed by 

 morphologists and taxonomists, who considered the clusters branched 

 or compound stamens, or "stamen systems." (Fasciculate stamens are 

 discussed under Androecium. ) 



Anatomy of the Stamen 



Stamens with well-differentiated anther and filament usually have a 

 single trace which continues as a simple vascular bundle through the 

 filament to the anther and sometimes into the distal prolongation. 

 Branching in the connective is occasional, but the branches bear no 

 relation to sporangium position. In delicate stamens, the vascular supply 

 may be vestigial and discontinuous or even absent; where absent within 

 the stamen itself, it may be present as a vestigial "stub" in the re- 

 ceptacle — some Scrophulariaceae. 



A two-trace supply to the stamen is rare: Austrohaileija, Sarcandra (a 

 vesselless genus of the primitive Chloranthaceae), some of the Pro- 

 teaceae, Victoria and some other genera in the Nymphaeaceae, 

 Casuarina, and some of the Betulaceae. The filaments of Nuphar, 

 Cyrtandra, Eranthemum, and Peristrophe were long reported to have a 

 pair of bundles, and that of Donjanthes, four bundles. In Casuarina, 



