KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. NIO 5. 



167 



preceding. The interlacunar bundles usually appear 

 in two circles and the central cylinder has a more 

 rounded or rhomboid cross-cut form. The cortical lacimar 

 system consists of 4 circles of rather narrovv and equal 

 canals. In the preceding the difference between the 

 inner and outer ones is relatively greater. The trio 

 is transformed into a single bundle. 



Distribution: New Zealand, Nepan River, 99, 

 Maiden (hb. Stockh.). Also in Eastern Australia. 



O 



O oao 

 °<^ un 



^oPi^ b 



Fig. 83. /'. tricarinattis M. & B. A, 

 Cross-section of the stem, /;•. trio-bnndle, 

 clr, opposite bundle (for the rest, efr lig. 

 82), 8 j°. B, Pistil, o, side-view, 6, stigma 

 from above. ',°. 



P. sessilifolius n. sp. — Fig. 84. 



Caulis 0,5 m altus et ultra, internodiis 5 — 6 cm longis, teres ca. 2 mm. in 

 diametro crassus, simplex, a basi pednnculi ramis spiciferis l:a3 — 2:se ordinis prolon- 

 gatus. Folia natantia cordato-rotundata v. subcordato-ovalia 15 — 17-nervia, 25 — 

 27 x 17 — 21 mm, petiolata, petiolis fol. floralium laminis longioribus, ceteris sequi- 

 longis; su b mer sa ovali-lanceolata sessilia brevissime cuspidata integerrima mera- 



branacea margine undulata 11 -ner via, 

 nervö medio reticulata, 65 — 100x13 

 — 18 mm. Ligulce membranacese fere 

 ecostatae subpersistentes amplectentes 

 ± 20 mm longae. Pedunculus crassitie 

 caulem sequans, ca 4 — 6 cm longus. 

 Spica florens 15 — 20 mm longa. Pi- 

 stillum stylo conspicuo fere ut in P. 

 muricato. 



The specimens of this species 

 I have seen lack fruit, but to judge 

 from the ovary the fruit will grow 

 sharply keeled and beaked, by vvhich 

 this species associates with P. muri- 

 catus and related. The floating leaves 

 are of about the same size as in P. 

 Cheesemanii which probably has caused 

 it to have been mixed up with that 

 species (J. Baagöe in hb. Lund.). 

 They have rounded apex and the base more or less conspicuously cordate. Lower 

 involucral leaves long-petioled (± 50 mm), upper ones with petiole and blade of equal 

 length. Submersed leaves evidently cuspidate, their base oval or oval-lanceolate. 



Fig. 84. P. sessilifolitts Hagstr. A, Floating leaf, J. B, Sub- 

 mersed lcal, j. C, Top of snbmersed leaf a little enlarged. D, Pi- 

 stil, side-view, 1 ,°. E, Anatomic diagram of the stem, showing the 

 mechanical system in the bark and the arrangement of the vascnlar 

 bundles of the stele, 2 , r ', c/j. epidermis, str, subepid. strand. 



