— 20 — 



Theoretically the bracts are reduced leaves, partly adnate to the axis, 

 and their phylogenetic origin is illustrated on an extremely clear way by 

 the successive reductions from a normal leaf unto a bract which are to be 

 observed in the peduncular leaves. 



Generally their form is elliptic or obovate with an ovate top, and their 

 lower portion from '/4 to "/s is adnate to the higher placed bracts so as 

 to form pouches while the free upper half forms by the upward bending 

 of its sideparts a sort of wide channel or gutter which continues the pouch 

 and the top of which is spreading or slightly recurved. 



The lenght and breadth of the free portion of the bracts is the cause 

 of a rather different habit in several species. In dried material it is often 

 very difficult to state this difference. 



Towards the top of the spike bracts and especially their free portions 

 become longer and narrower; in the same time the green colour changes 

 either into white or in some modicfcation of violet; generally a group of 

 intermedial bracts is found between these two forms. The uppermost group 

 forms the coma which has mostly a wider diameter than the rest of the 

 spike and of which the last developed bracts produce only rudimentary 

 or no flowerbuds. 



The arrangement of the bracts is rather equal in all species and very 

 regular. Nearly always may be observed 5 "parastichies" running in a rather 

 steep curve which together contain all the bracts and of which the bracts are 

 contiguous ("contact-parastichies"), and besides very often a system of 3 

 parastichies, running in a contrary direction and thus crossing the former 

 ones and being likewise contiguous. 



In the same species these 5-parastichies, „fünfer-Zeilen", (Schwendener), 

 "5-curves", (Church), run now to the right, now to the left without preference, 

 and the 3-parastichies (dreier-Zeilen) respectively the contrary. Tracing these 

 5 parastichies to their base one finds that their lowest bracts form together 

 a depressed spiral, seemingly a circle or whorl like that which is seen very 

 often in the disposition of the sepals of the dicotylédones and which is 

 called "aestivatio quincuncialis"; of this spurious whorl the first and second 

 leaf are placed outside, the fourth inside, the third and fifth half inside half 

 outside. Following this spiral along the surface of the spike it may be seen 

 that the 6th bract lies with the first in the same of the five parastichies above 

 mentioned, the 7th with the second, the 10th with the 5th etc. This curve 

 is the so called genetic spiral which contains all the bracts. According to 

 the number of the bracts being larger or smaller the five first bracts 

 (mostly including the 1—2 empty bracts) are placed in a flatter or 

 in a steeper spiral. The 4th always is placed somewhat higher between 

 the second and the first, the 5th between the third and the second, the 

 6th between the 4th and 3tli etc. This curve naturally is no contact-line. 



