KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. N:0 5. 



41 



P. jlahellatus Bab. may nowadays by all investigators be acknowledged as a 

 fectinatus-iovva. 



Common characteristics of the numberless forms of this species (das Chamaleon 

 unter den Laichkrautarten : E. Baumann) are the elongate, sharp points of the 

 youngest leaves of the sterile short-branches, the cuspidate involucral leaves 

 with a more or less conspicuous mucro, the more or less broad, hght (whitish — pale- 

 green — whitebrown) membranous border of the sheaths, the large, oblong-shaped 

 or ovoid (rarely almost spheric) pollengrains, the more or less conspicuous styles 

 with sloping stigmas, and the more or less large (3—4,5 mm X 2 — 3 mm) fruits, 

 whereto is to be added the way of branching (fig. 15, B) and producing its spikes, 



B 



Fig, 15. P. pectinalui L. A, Hibernating rhizomatic tnrio {nat. size), deprived of its basal scales; f^ prophyllum, s?, 

 scale-leaves, /, //, ///, the dift'erent generations of the tnrio, 1, 2, 3, 4, 5, 6, their different internodes. The dotted lines indi- 

 cate the places for concretion of internodes. The 3d and 4th internode of the different generations partake in forming the 

 bnlbs, cf. fig. 3, C, Df B, Ramification, somewhat schematized, -] ; a, mainshoot, h, leaf with sheath and lignle (rf), clasping 

 the basal parts of 3 evoluted branches {1, S, 3), f, prophyllum, I', I", scale-leaves, <-, first laminated leaf of the branch 1. The 

 first three internodes of this branch are commonly very short, together only about one mm. Or only the first two internodes 

 are short (about 1 mm) and the third one elongated, the sheath therefore clasping only two branches, or, if I' is sterile, one 

 single branch. From the scale I" occasionally springs a rhizome; f is always sterile, cf. Fig. 11, D. C, Transverse section of 

 young sheath, basal portion, showing the site of the free borders, rt, h, as in Fig. 3, B, '^^ . D, Pistil, lateral view showing the 

 free beak of the style, ^^. E, Stigma, and the just mentioned beak, from above, more enlarged. 



after the type C (Fig. 2) except in the f. geminatus m., see below, p, 51. On 

 the systematic importance of the turios. Fig. 15, A, see Hagsteom, Potamogeton 

 in Neuman, Sveriges Flora 1901, 794! On the anatomical facts, see below, 

 Fig. 16! 



Concerning the leaf -width it may be remarked that the leaves cf the main- shoot 

 are always broader than the branch-leaves, and the lower leaves of a shoot also 

 broader than the upper ones. — Different statements are to be found about the 

 fruit-form, some authors (Chamisso, E. Fries, Gussone, and others) describing it as 

 keeled on the back, others, for instance, Grenier, Marsson, Morong, Kihlman, 

 VuYCK, as without keel, others finally (Ascherson and Graebner) as keeled or un- 

 keeled. The cover of the putamen is always rounded without keel and the flesh 



K. Sv. Yet. AkiiJ. Handl. Band 55. N:o 5. G 



