110 



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



The stem is 

 pseudo-hypoderma 



str 



flattened in the relation of about 2,3 : 1. Its endodermis has a 

 with the usual subepidermal strands. The central cylinder pre- 

 sents the common oblong diagram. In the peduncle, being 

 2,5 — 5,5 cm in length, the four vascular bundles run separated 

 by distinct interspaces. The hypoderma and the subepidermal 

 strands we refind, as in the stem, though the latter are a 

 little reduced in number and strength. The leaves have a 

 more or less rounded base and a more or less tapered and 

 cuspidate apex. The proper stem-leaves are 5-nerved, the 

 branch-leaves usually 3-nerved. The former resemble very 

 much a mucronatus-leai, but the midrib is on either side accom- 

 panied by 3 rows of lacunae in its basal half with mechanical 

 strands running subepidermally. The ligules are convolute and 

 exhibit 8 — 11 strands in the front-field. The style is short, 

 stigma rounded or oval, broad and expanded (see the fig. 45, G!). 

 Distribution. Brazil: S. Paulo, Santos, 74, Mosbn (hb. 

 Stockholm., Uppsal., Lund.), »A. 821 », Lindman (hb. Stock- 

 holm.). — The plant from S. Paulo, Amparo, Lindbeeg. (hb. 

 Stockholm.), with shorter (6—20 mm) internodes seems to be a 

 hybrid (see p. 113). 



P. Berteroaiius Philippi. 



Plantarum novarum Chilensium etc. in Linnsea 1859 — 60, 

 200. - Fig. 46. 



The discoverer of this plant has confounded it with 

 the species afterwards named P. Aschersonii. I have in fact 

 seen specimens from the very locus classicus, Tagua-Tagua, de- 

 termined by Philippi himself. They are not P. Berteroanus, 

 but P. Aschersonii. The two species have of course grown 

 together, but the author has made his description according to 



the broader-leaved form, since he writes, »foliis — 5-ner- 



viis», whereas P. Aschersonii has, at least in general, 3-nerved 

 and narrower (1,5 — 2 mm) leaves. 



Stem distinctly compressed (2,5: 1) and anatomically built 

 up according to the usual type of the group with a one-celled 

 or at the edges 2-celled pseudo-hypoderma and a full number 

 of subepidermal strands. Central cylinder of the oblong dia- 

 gram type. Peduncle almost terete with scattered subepi- 

 dermal strands in the one-celled hypoderma. Vascular bundles 

 four, the median running together, the lateral ones more distantly from the centre. 

 Leaves 5— 7-nerved. On either side of the midrib there are three (in the stem- 

 leaves) or 2 (branch-leaves) rows of lacunae. For the nervation I refer to the fig. 



Fig. 45. P. Gayii Benn. 

 A, Transverse section of ped- 

 uncle showing the course of 

 the vascular- and bast-bun- 

 dles, '^. Bj Transverse section 

 of a stem-leaf below the middle 

 showing the lacunar system of 

 the midrib and its .strands {str) 

 the disposition of the vascular 

 bundles {in n' n") and the mar- 

 ginal strand, ^-^. C, Pistil, a,- 

 side-view, Z), dorsal view, c, 

 stigma from above, y. 7>, 

 Transverse sect, of a ligule at 

 the base showing the form of 

 an open, convolute ligule, Y, 

 ic, front-field, ;•, ridges. 



