C. II. Ostenfeld: Contributions to West Australian Botany. I. 43 



shoot Fig. 29. Halophila 

 eaves 8pinulosa.The apex 



The 



of an assimilative 

 shoot, twisted by 



[ About */i nat. size). 



of one-celled acute teeth. A transverse section at the middle (Fig. 



27 a) shows that the middle vein is somewhat nearer the one 



margin than the other. This obliqueness is more 



pronounced in a transverse section near the base 



where the ear-shaped part is met with (Fig. 27 b). 



Here the middle vein is found in the upper 



half of the clasping leaf- base. 



The first leaves of an assimilative 



are transitional in form between the scale 



of the rhizome and the foliage leaves. 



pairs are somewhat distant in the lower part of the pressure of the 



the assimilative shoot; further up they are more 



closely placed, partly covering one another. 



Probably the assimilative shoots are comparatively short-lived, 

 while the creeping rhizome steadily renews 

 itself by new shoots, the ulder dying away 

 behind. 



Towards the apex of some assimila- 

 tive shoots male flowers were present in 

 the axils of the leaves, and owing to I heir 

 presence the regular edgewise arrange- 

 ment of the leaves is somewhat disturbed. 

 The flowers press the leaves apart, and by 

 this pressure the upper part of the shoot 

 becomes more or les spirally twisted (Fig. 29). 

 The male flower is placed solitary in 



the axil of an ordinary foliage leaf, 



and is enclosed in a two-leaved in- 



volucrum (Fig. 30). The outer in- 



volueral leaf is nearly two-keeled 



(one acute and one blunt angle) with 



a flat back; towards its apex it is 



somewhat spinulose-serrate (Fig. 30a). 



The inner involucraJ leaf encloses the 



flower bud ; it is one-keeled and has 



a long-pointed apex (Fig. 306). The 



flower itself consists of three perianth 



leaves which, when they open, bend 



backwards and force the edgewise- Fig. 31. Halophila spinulosa. T runs- 



verse section through a male 

 set leaf a little aside. The perianth flower, showing the two involucral 

 leaves are obtuse ovate -oblong leaves, the three-leaved perianth 

 . . ., i t -i .i • and the three anthers. (About 



lamtly one-nerved. Inside the peri- »/ n at. size). 



Fig. 30. Halophila spinu- 

 losa. Male flower, a and 

 b, outer and inner in- 

 volucral leaves ; r, flower 

 bud with involucrurn; d, 

 open flower with emptied 

 anthers and backwards 

 bent perianth. (About a /a 

 nat. size). 



