KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. NIO 5. 85 



are of the same thickness. Epidermis-cells 4 — 5 times as long as broad; endodermis, 

 lacunar system, and central stele just as in the coordinate. 



Leaves with low midrib and slightly developed lacunar system in contradistinction 

 to P. sibiricus Benn. possessing a broad median areolation-area. Bast-bundles and 

 vascular bundles as the fig. shows. The chief lateral nerves join the midrib in the 

 very apex especially in the involucral leaves, which are also a little more obtuse than 

 the lower ones, but always lacking the lacunous structure, which is characteristic to 

 part of the Pusilli. 



The style is very short and the stigma expands över the börder of the style. 



The species differs from P. sibiricus Benn. by the stem being narrower, the 

 ligules brown, the spike 6 — 8-florous, and by the absence of the leaf-areolation men- 

 tioned above. Fruit not seen. 



The material examined originates from Sibiria, Yenesei, Dudinka, 69° 35 f n. lat, 

 col). H. W. Arnell, 1876 (hb. Stockholm); Nikandrovskij ostrov, 70° 20' n. lat., in 

 a small lake, 76 V (flowering), Arnell (hb. Stockholm.). P. subsibiricus may belong 

 to the tundra-lakes of north-west Sibiria, whereas P. sibiricus may have a more 

 easterly distribution. 



Subsectio 12. Monticoli Hagstr. 



Caulis teres v. subteres, pedunculis valde elongatis. Folia angustissime linearia, 

 uninervia, laete viridia, in apicem tenuissimum subobtusum longissime attenuata, per 

 totam latitudinem loculosa. Ligulce fissse, binerviae, in spatio intercarinali enerviae. 

 Pistillum stylo brevi, stigmate parvo. Fruetus subglobosus dorso carinatus, lateri- 

 bus levis. Operculum angustum, carinatum. 



Dr. C. Raunkler is the first that has established the »P. confervoides-grovp» 

 (Anat. Pot. Stud., 268) because of the lack of subepidermal bast-bundles in the bark 

 of the stem. Prof. P. Graebner, again, has reunited the species with the Pusilli. 

 The species, however, deserves its particular position not only because of the above 

 remarked condition, but also on account of the stem-hypoderma, the structure of 

 the leaves and ligules, the different central cylinder of the stem and pedunele, the 

 fruit etc. 



Its distribution-area is rather narrow: the north-east parts of the United States 

 of America. 



P. confervoides Reichenbach. 



Icones Florse Germanicae et Hefveticse etc. Vol. VII, 1845, 13. — P. Tucker- 

 mani Robbins ap. A. Gray, Manual of the Bot. of the north. U. S., 1856, 434. — 

 P. monticolus Schweinitz ap. Ar. Benn. in Ann. naturh. Hofmus. Wien, 1892, 292, 

 nomen solum. — Fig. 1, G, 34. 



As the P. polygonus, respecting the development of stem-sclerenchyma, forms 



