58 



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



P. crispus L. 



Species plantarum 1753, 126. — P. serratus L. 1. c. — 

 Prodromus Fl. Nepal. 1902—3, 22. — P. tnherosus Roxburgh, 

 12. — P. serrulatus Schrader ap. Opiz, Flora V, 1822, 227. — 



Fig. 21. F. crlspus L. A^ B, C, Tops of stem-leaves of the var. oZ»- 

 tiisifoUus FiEB. (slightly enlarged); />, Upper part of a stem-leaf of v. acuti- 

 folius FiEB. (slightly enlarged); E, Pistil, lateral view, a. the point whore 

 it is fixed at the receptacle, si, stigma, -J; F, Longitudinal section of the 

 receptacle (a) with two fruits showing the point of concretion (p), b, rostrum, 

 c, dorsal keel with a basal horn-like boss, {-; 6r, Figure showing the rela- 

 tive size of the pollen-grains of, «, P. cn'spus, h, P. jjerfoliaiiis and pycelongus, 

 (.', P. jixsillus; H, Diagram of the stem's axial cylinder, k, bundles, t/% bundle 

 trio, eft; opposite bundle, Ih, lateral bundles, jj, pith; JC, Transverse section 

 of the middle lacunar part of a leaf (upper part near the middle), ni, mid- 

 rib, ^^ Lf Part of the leaf margin with 2 teeth each ending in a greater 

 top-cell, a (enlarged); M, Transverse section of leaf margin, ((5, upper 

 surface, Js, lower surface, h, a faint marginal strand, y^. 



the 



P. crenulatus Don, 

 Hortus beng. 1814, 

 P. crispatus Wall- 

 man ap. Fries, Nov. fl. Suec. 1828, 

 43. — P. laclucaceus Montand., 

 Guide Bot. 1868, 305. — Hue 

 etiam species Gandogerianse perti- 

 nent: P. hungaricus, P. rubricans, 

 P. pallidior, P. Hohenackeri, P. 

 Notarisii, P. leptophyllus, P. ru- 

 brincevus, P. macrorrhyncus et 

 P. austriacus Gandog., Pugillus 

 plant, nov. etc. in Osterr. Bot. 

 Zeitschr. 1881, 43—44. - Fig. 

 21, 22, 24, A. 



The furrowed stem and serru- 

 late leaves connect this plant with 

 the precedent group. An abund- 

 ant evolution of hibernating and 

 propagating cauline buds char- 

 acterizes this species as well as 

 the foregoing and next-following 

 groups. The air-channels of the 

 leaf, in the upper part 1—2 on 

 each side of the midrib, increase 

 in number toward the base, form- 

 ing there a broad area of 4 — 5 

 rows on each side. One or two 

 pairs of lateral nerves are running 

 rather near the margin, by which 

 the species exhibits affinity with 

 the Pusilloids especially P. obhisi- 

 folius. The ligule is often at its 

 base slightly grown together with 



leaf, a fact observed in P. ochreatus also. 

 The style is elongated and the oval stigma fixed obliquely. By this fact the 

 present species and group is distinguished from its relatives; also by the ovaries, 

 which at first isolated from each other grow a little together below, when ripening 

 to fruit and increasing simultaneously their receptacle. The rostrum, in fresh state 

 being conic and erect, curves itself more or less backwards, when drying, by the 

 dorsal spongy parts of it shrinking more than the inside. The dorsal keel ends in 



