172 



J. A. EAGSTROM, CRITICAI, EESEAECHES ON THE POTAMOGETONS. 



P. porrigens n. sp. — Fig. 89. 



Caulis elongatus teres tenuis subfiliformis simplex, internodiis summis elongatis, 

 10 — 25 cm, a spica primaria ramo internodiis longis prolongatus. Folia natantia 

 parva 15 — 20 X 5 — 6 mm, oblongo-lanceolata, apice obtusa basi attenuata, 5 — 7-nervia, 

 loncfissime (10 — 15 cm) petiolata, petiole filiformi; submersa lineari-lanceolata 

 sessilia— subpetiolata, apice obtusa, 50 — 60 X 3 — 4 — 5 mm, integerrima 3( — 7)-nervia. 

 Ligulm membranaceae cito evanescentes breves (o — 15 mm longse). Pedunculus aequalis 

 filiformis, 10 — 12 cm longus. Spica 5-verticillata, deflorata 8 — 10 mm longa. Fruc- 

 tus non visus. 



. This species, the fructification of which, on account 



of the defective material, can not be described, yet is 

 easy to identify by its elongate filiform upper internodes, 

 peduncles, and petioles and by the minute floating 

 leaves. Spikes usually with 5 verticils and thus 

 small. The submersed leaves are as to form and size 

 almost quite like those of P. sderocarpus, but destitute 

 of the midrib canals, there always present, beside which 

 the nervation also is different. To judge from the 

 description of P. Drummondii and from a diagram of 

 the central stele of it drawn by C. Raunki^r in his 

 Anat. Pot. Stud., 265, f. 4, A, P. porrigens would be 

 very closely allied with that species. But the stem-ana- 

 tomy of P. Dnmim. runs: ep. + subep. str. + lig. str. (±) 

 + 0-end. + CC eight-bundled, accord, to Dktjmmond's 

 own spec. (hb. Haun.), and, besides, its habitat is 

 West Australia, in consequence of which I cannot 

 consider them identic. Nor is it congruent to the 

 P. Cheesemanii, with which it shares a common distribution, though extremely nearly 

 related also to that multiform species. 



In the topography of the stem-anatomy we immediately observe the compressed 

 central cylinder with two prominent median bundles {mh) and small lateral ones {lb), 

 one on either side, all separated by a stroiig central mechanic tissue. Besides we 

 notice an 0-endodermis, no interlacunar bundles, no strengthening layer, but a few 

 subepidermal strands. Three circles of lacunse of the usual form. 



Distribution. Nova Zelandia: Hokianga, 74, Berggren (hb. Stockholm., 

 Uppsal., Lund.). 



Fig. 89. P. porrigens Hagstk. A, Base 

 (a) and top (b) of a snbmersed leaf; the 

 interrupted lines indicate nerves frequently 

 appearing, but which also wholly or partly 

 can be absent, -J-. B, Floating leaf, \. C, 

 Diagrammatic crosssec-tion of the stem show- 

 ing the central cylinder, epidermis and sab- 

 epidermal strands, \°, inb, median bundles, lb, 

 lateral bundles. 



P. recliinciis n. sp. — Fig. 90. 



Caulis tenuis internodiis summis ca. 5 cm longis. Folia submersa membra- 

 nacea lanceolata, apice obtusa basi attenuata sessilia vel subpetiolata 5 — 7-nervia 

 integerrima ca. 50 — 150 X 5 — 10 mm; natantia rariora minora Jonge petiolata obtusa. 



