114 



J. O. HAGSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



P. oriontalis Hagström. 



New Potamogetons, in Botaniska Notiser, 1908, 102—103, with figures (tops 

 of stem- and branch-leaves). — Fig. 49. 



The stem of this species is compressed (2,5 : 1) and slightly furrowed or even 

 two-sidedly furrowed. The arrangement of the vascular bundles of the stele is the 

 same as in other kindred species and the stele diagram is oblong. The epidermis 

 lacks a strengthening layer, but has rather strong subepidermal strands, whieh, how- 

 ever, do not continue in the peduncle. The four vascular bundles 

 in the peduncle run rather near to one another. The stem branches 

 dichotomously from the primary spike. 



The leaf has about the same shape and size as that of P. 

 attenuatus. The lacunar system also is much the same, consisting 

 of three to four larger channels on either side of the midrib in 

 the basal part, conducted by 2 — 3 subepidermal bast-bundles as 

 the figure 49 shows. But the marginal strand has the usual faint 

 structure. In the basal part and more or less far above the middle 

 the stem-leaves usually are 5-nerved, the topmost third part, or 

 so, in general 3-nerved. The main side-nerves join the midvein 

 in the very apex. Ligules with large basal oil-cells and 8—10 

 intercarinal bast-bundles. 



To judge from the rather scanty materials the styles seem 

 to be enlarged above and the stigmas small, roundly oval. 

 Fruit is not yet seen, but the i)lant is undoubtedly nearly kindred 

 Fl " * 9 - ''■ ■■ with /'. pusillus L. 



.i. 'i'. , nsi i i se sec- 



the midrib pai-t <>f Distribution. Japan, R. Tama, Musashi, 88, Makino (hb. 



asnai, V- b, Transv. sect. Stockholm.). — Assam, JBrahmaputra al Dilmgach, IMm, u:t K.1NQS 



: Collector (hb. Hann.). China, Ichanq (hb. Haun.). Probably in 



' ' '".','• i ho whole of East-Asia. 



Ha 



I\ 1'ronssii Ar. Hhnnktt. 



NajadacesB in thé Flora of trop. Africa, VIII, 2, 1901, 222. Fig, 50. 



Ilaving had no opport unil y to examine the young ligules of the original spo- 

 oimens, I rank the species liere additionaliv and <ul interim on acoount of the affi- 

 nily with /'. Hillii, slatcd by the author. Besides, the stom-anatomy is congrucnt 

 lo thal of the South American /'. Berteroanus, and the shape and structure of the 

 leaves eorrespond closely with those of /'. orientalis. The affinity with the Compressi 

 does not seem to be greater in this species t han in the group on the whole. The 

 leaf-form reminda also of that of /'. rutilus. Pistils and fruita are not known to me. 



The stem is oearly terete and with a ahallow furrow as the figure shows. 

 Along the epidermia a one-celled strengthening layer is arranged beaide the usual hast- 



