. Critical researches on the potamogetons. 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 lon
. Critical researches on the potamogetons. 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), o
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