Box.— Vol. I.] CANNON— A VENA FATUA. 333 



The carpel is the last of the floral organs to arise. It 

 appears as a single ridge of tissue on the anterior side of 

 the floral axis (fig. 6), and gradually encircles the apex 

 of the young flower (fig. 6a). The young carpel is club- 

 shaped in longitudinal section, and its structure is suffi- 

 ciently indicated by the figures. Soon after the carpel has 

 completely surrounded the tip of the flower axis, two pro- 

 tuberances appear on the sides and form the beginnings of 

 the stigmas; later the rim of the carpel closes and shuts in 

 the ovule. 



A correct interpretation of the relations of the parts of 

 the grass flower is of great iniportance, because upon it 

 depends a right understanding of the relationships of this 

 isolated family. These relationships are based mainly on 

 the number and arrangement of the floral organs. The 

 origin and development of the gynoeceum and androeceum 

 of the grass flower, as well as the origin and development of 

 the organs subtending these, are now fairly well understood, 

 but the morphological significance of some of these organs 

 is very much in doubt. It is not known, for instance, 

 whether the lodiculas represent a perianth or not, an impor- 

 tant basal fact in determining the position of the grasses. 

 There are concerning the lodiculee two widely different 

 views which have been held by botanists. In the first, the 

 lodiculae are considered to be the stipules of a leaf which 

 has been suppressed, or the parts of a leaf of which the 

 middle is wanting; and the posterior lodicula when present 

 is held to be, according to this hypothesis, a leaf or palet 

 which alternates with the lodicular palet and which there- 

 fore continues the distichous arrangement of the lower 

 glume and upper palet. Or, in other words, according to 

 this interpretation of the grass flower there are represented 

 four alternating palets of which the two lowest persist, the 

 others being rudiments. This explanation of the relation of 

 the lodiculse to the other organs of the grass flower is 

 opposed to the law which is sometimes said to govern leaf 

 arrangement among the grasses, by which the leaves of a 

 branch are inserted on a plane at right angles to that of -the 



