108 



J. O. HAGSTROM, CR1T1CAL RESEARCHES ON THE rOTAMOGETOXS. 



labelled > Herb. of the U. S. North Pacific Exploring Expedition under Commanders 

 Ringgold and Rodgers 1853 — 56. C. Wright coll. Loo-Clioo Islands». They are 

 determined by Maximowicz himself as limosellifolius. 



In habit and in most qualities it is like a small P. panormitanus. Regel in 

 Fl. Ussur. plainly calls it P. pusillus. 



The stem is thread-like, terete or but faintly compressed and to the inner struc- 

 turc corresponding with the usual type of the group. The subepidermal strands are 

 very faint; no pseudo-hypoderma; central cylinder of the circular diagram type. 



Leaves three-nerved, stem leaves 20—30 mm long, scarcely 1 mm broad, base 

 tapering, apex with a short cusp; a narrow channel on either side of the small lacunre 

 round the midvein (/ — l), no strands are observed in the lacunar system. Accord- 

 ingly P. limosellifolius is a non-sclerenchymatous species. The involucral leaves are 



semicoriaceous in close correspondence with P. panormitanus. 

 Blade and petiole more or less distinctly differentiated; bkule 

 without stomata, not fully 2 mm broad. Ligules 8-fibrous con- 

 nate as in P. panormitanus. 



The spike consists of only two verticils. Style short, stigma 

 almost oval covering the whole upper surface of the style and 

 projecting a little beyond. The fruit lacks a dorsal kcel and 

 outgrowths according to the outline of it made by Maximowicz 

 on the label, and is somewhat like a panorm itanus-iruit, but 

 shows no affinity with the Javanici. No turios are seen by me. 



I C 



I 



Fig. 43. /'. limosellifolius 

 .Maxim. A, Top of submersed 

 1' Jif showiog the n< nation and 

 the form of tho ensp, f. Ii, 

 Two involucral leaves (a — /;) 

 //, more conspicnOOBly diffe- 

 rentiated, J. C, Transverse 

 section of a snbmersed leaf, 

 ";", see the text! b, PiatU, 



view, J. 



Series B. Pusilli convoluti Hagstr. 

 Subscries a. Acuti Hagstr. 



All the species of this subscries have a distinct, sharp 



cusp, or a slowly tapering point. I do not know more t lian 



the following seven species and hybrids: P. Hillii, P. Ga t/i i, 



P. Berteroanus and P. Aschersonii, belonging to North and South America, P. oricn- 



talis a nativc of East Asia, and P. Prcussii, of Africa. A South-American hybrid 



shows evident relationship to P. Aschersonii and polygonus. 



P. Hillii Morong. 



In Botanioal Gazette 1881, 290. — Fig. 44. 



Slem flattcned and furrowed at least on onc side, 2,e times as broad as (hick, 

 and of fche typical Btruoture; Btele diagram oblong. Epidermis-cells of elongated form, 

 W to 5 times as long as broad; a pseudo-hypoderma laoking in t lie slem is present 

 in the peduncle, where, again, the sclerenchymatoaa strands are absent. Thé vas- 

 Olllar bundlcs of the I ätter rim verv near together reminding in that eirennistanee of 



