19 
one side of a spadix, which is enclosed in the sheath-like base of a 
leaf (spathe); male flowers with 1 sessile anther; pollen thread-like, 
female flowers with 1 ovate-oblong ovary attached near the apex; 
stigmas 2, long; fruit drupe-like, bursting, enclosing 1 cylindrical, 
ribbed seed. 
Am.: Port Clarence (!), West Greenl. c. 64° 30’ (!). 
Geogr. area: Pacific coast of North America to California, Atlantic 
coast to Florida, Iceland, Farées, Coasts of Europe and Asia Minor. 
2. POTAMOGETON L. 
The Potamogeton being in the Arctic countries usually sterile, the characters 
in the key are always taken from the leaves. 
A. Stipules adnate to the leaves, leaves capillary, obtuse. ...... P. filiformis. 
B. Stipules free. 
a. Leaves all alike, linear, entire, with 3—5 nerves. 
1. Leaves with 3 (1) nerves, acuminate, acute or subacute. . . P. pusillus. 
2. Leaves with 3—5 nerves, acuminate, obtuse....... P. obtusifolius. 
b. Leaves broader with many nerves. 
1. Leaves all alike, submerged, sessile. 
* Leaves ovate or lanceolate-ovate from a cordate-clasping base, obtuse 
(onssubacute) ir e-wegerics sackets nee mens el trenchant P. perfoliatus. 
** Leaves lanceolate-ovate, half clasping, cucullate at the apex 
P. praelongus. 
2. Upper leaves floating, petioled (sometimes wanting); lower submerged, 
linear-lanceolate or oblong, sessile. 
+ Submerged leaves linear-lanceolate, attenuated at the base, cuspidate, 
ieee AVON 6G colt. c im © iduosono mi dioto en dig olptoRone P. gramineus. 
+t Submerged leaves long, linear lanceolate, broader at the base, margin 
STOOtH 7s jdarlsy Sa oS hagas okoti eS pehelistsy ale saaketatele P. alpinus. 
38. P. alpinus Balb. 
P. rufescens Schrad., Lge. Consp. Fl. Groenl. p. 116 and p, 282; Ro- 
Senve Quill’ p. 710; Fl D: t.1450; 1635. 
Floating leaves obovate or oblong-lanceolate, obtuse, narrowed 
into a short petiole, passing into the submerged ones; submerged 
leaves oblong-lanceolate to linear-lanceolate, translucent, obtuse, 
green (reddish-brown when dried); spike many-flowered; fruits 
reddish, obovoid or lenticular, keeled; rhizome creeping with ro- 
bust propagating bud-like stolons. 
Am.: West Greenl. 61°—67° (!). 
Geogr. area: Northern North America, Iceland, Ferées, Europe, 
Northern Asia, Afghanistan, Tibet. 
39. P. gramineus L. 
P. heterophyllus Schreb., Lge. Consp. Fl. Groenl. p. 117 and 282; 
Rosenv. Till. p. 710, Nye Bidrag p. 70; Fl. D. t. 222, 1263. 
te 
