84 



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



The lacunar median part of the leaf consists of the usual small lacunae round 

 the median vascular bundle. On either side of those small channels, in the lower 

 half of the leaf, run two rows of large lacnna? and thin bast-bundles in the conjunctions 

 between the lacunar walls and the epidermis. On both sides of the lacunar part the 

 small strands run at rather short intervals from each other as the fig. 32, C, shows 

 looking outwardly like fine nerves. The var. Fauriei Benn. also has the same struc- 

 ture. The only difference is that the bast-bundles are considerably stronger, by which 

 the leaf grows stiffer and more resistive. 



B 



D 



E. 



The leaf-apex gradually tapers 

 and exhibits an asymetric form just 

 as P. polygonus and others (Fig. 32, 

 A, b). The base is somewhat round- 

 ed, sessile, not subpetioled. The 

 style is short, but distinct, and a 

 little incrassate upwards, as is the 

 case in a good deal of species, and 

 the stigma small, roundish-oval, not 

 covering the whole upper surface of 

 the style (Fig. 32, B). Pollen of 

 small grains, spherical. 



Distribution. Japan, Nippon 

 prov. Nambu, 65, Ichonoski (hb. 



^QQS 



\0cp 0o °^^n0^ Stockholm.). It belongs to the easter- 



Oo°po n/ ' m °st Asia, how far to the south and 



north is not yet fully known. 



Fig. 33. /'. »ubaibirieua Haqsts. A, Transverse sec- 

 tion of a stem-leaf at the middle, \'\ '"• mM-vein, «'. 

 latera] vein, str. bast-bundles, /, lacunar system. B, Top 

 of B stein-leaf, ;. C, Ligalc, \. 1), Pistil, j. K, Trans- 

 verse section of stern, Y', e P, epidermis, /, lacunar Bysten, 

 Hr, siibopidermal bast-bnndles, ee, central axis. 



P. snfosibiricus n. sp. 



Caulis ca. 5 dm altus, compres- 

 sus (— ) filiformis, 0,5—1 mm latus, 

 parum ramosus, supra spicam pri- 

 mariam vix prolongatus ramis spiciferis, internodiis 3 7 cm longis. Falla anguste 

 linearia, caulina ca. 2 mm lata, 40—60 mm longa; summa ± 40 mm longa, basi rotun- 

 data, apice cuspidata, 13 17-nervia vel ultra. Ligulic ca. 15 mm longa?, obtusae, 

 badise, basi glandulosse, fissae, in spatio intercarinali 10 — 13-nervia\ PedunetUus com- 

 pressus aequalis, 20 — 35 mm longus, Spica ± densa 3 — 4-verticillata. PiatiUum styh» 

 brevissimo, stigmatc complanato rotundato expanso. Pollen parvuni spluvroidcum. 

 Pructus non visas. — Fig. 33. 



The anatomy of stcm and pedunole is much the same as in the foregoing. 

 The stem is providcd with subcpidermal bast-bundles and deprived of hypodcrmatic 

 layer, in tlie pcduncle the condition is the reversed: no strands but a 2-celled strength- 

 ening layer, which, bcside the scattered position of tlio vascular bundles, makes the 

 peduncle bbviously thickei than the slem. In /'. oxyphyUus tlie stem and peduncle 





