CALIFORNIA ACADEMY OF SCIENCES. 125 



P. tenue, Michx. 



Glabrous but not at all glaucous, | — -1 foot high, the stem 

 and branches slender but wiry and strictly erect: sheath 

 of stipule 3 lines long, herbaceous, red-brown in age and 

 persistent, the hyaline portion of equal length and fimbriate- 

 lacerate: leaves thickish, erect, linear, acute, distinctly 3- 

 nerved; their margins strongly ciliolate-scabrous, as also is 

 the midrib beueath, and often one angle of the stem and 

 branches: floral leaves subulate, remote, flowers solitary in 

 their axils, on erect pedicels : akenes usually dull black, in- 

 closed by the calyx, in outline broadly ovate. — Michx. Flora, 

 I. 328; Meisn. in DC. Prod. XIV. 100. 



Common on the Atlantic slope of the continent, from Can- 

 ada to Carolina and westward to the Mississippi. 



P. Eouglasii. 



Glabrous and somewhat glaucous, often a little scabrous 

 about the nodes, 1 — 1| feet high, with numerous, slender, 

 divergent branches: leaves thinnish, oblong to lanceolate, 

 1-nerved, their margins smooth and more or less revolute; 

 stipvdes entirely hyaline, the sheathing portion very short, 

 or wanting, the upper part more or less lacerate: floral leaves 

 reduced: flowers commonly more than one in each axil, their 

 pedicels deflexed: akenes longer than in the preceding, 

 shining or granular-roughened. — P. tenue, Watson, Bot. 

 King. 315; Bot. Cal, II. 12, but not of Michx. 



var. latifolium. 



Leaves oblong : flowers numerous and crowded into a spike : 

 face of akene rather oblong than ovate in outline. — P. tenue, 

 \*ar. latifolium, Engelm. 



From the Saskatchewan to British Columbia, and south- 

 ward everywhere in the mountains to the borders of Mexico. 

 Clearly distinguishable from its eastern analogue by the 

 characters indicated, of which the 3-parallel-nerved leaves 

 and their almost saw-toothed margins are the most obvious. 



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