the Inflorescence of Dionaa, 47 



A cross section of the branch G of Plate V, made a little- 

 above its insertion into the scape, is represented in Plate VI, 

 Fig. 5. Beneath a single layer of epidermal cells is a wide- 

 zone of fundamental tissue, succeeded by a layer <>f scleren- 

 chyma interspersed by white, glistening, sclerotic cells. In- 

 ternal to these is a zone of phloem tissue surrounding a 

 central mass of xylem. The course of the bundles in the 

 branch can now be referred to. The leaves are arranged in a 

 flat alternate spiral (Plate VI, Fig. 3). Fraustadt (op. cit.) 

 says : "The whole rhizome is short and broad, the leaves are- 

 placed on it with broad, flat insertions without internodes." 



"The phyllotaxy I have not been able clearly to define, the 

 younger leaves are apparently two-ranked ; the leaves overlap 

 one another with their foliaceous petioles." "Frequently the 

 leaves show an open spiral arrangement." The abnormality 

 with lengthened internodes (Plate VI, Fig. 3) is especially 

 valuable, as it indicates more plainly the phyllotaxy and the 

 distribution of the fibro-vascular bundles. Fraustadt, in his 

 study of the underground short rhizome, encountered a mass 

 of fibres. A cross section of the abnormal branch, half-way 

 between its proximal and distal ends, appears in Plate VI, Fig. 

 6. Fig. 2 shows the relationship of the parts. The central 

 tissue of the branch shows the main bundle trace (A) two 

 leaves (C and E) come off from either side of this central 

 area, a third leaf (O) arises above. 



A very thin section, at this point (A, PL VI, Fig. 2), is 

 magnified and shown in Fig. 6. We have in this figure the 

 central tissue (A 1 ) with the two leaves arising on each side 

 (C 1 and E 1 ), the third leaf O 1 arising above. A puzzling 

 ramification of bundles here occurs, complicated by the dif- 

 ferent directions of leaf growth. The bundles at the proxi- 

 mal end of the rhizome are represented in Fig. 5, Pi. VI. 

 When we reach the middle section, Figure 6, a change takes 

 place. Before dividing into separate strands for the leaves 

 (C 1 , E 1 , O 1 ), a twist in the stem bundles must occur for the 

 three phloem areas come together at A 1 , with the xylem circum- 

 ferential. The leaves in their origin run toward the growing 

 point a little way, then take a sharp bend, and point backward 



