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NEW PLANTS FROM MISSOURI. 



BY K. K. MACKENZIE AND B. F. BUSH. 



Sagittaria brevirostra Mack. & Bush,sp. nova. 



A glabrous monoecious perennial growing in swamps. 

 Leaf-blades with petioles about 3 dm. long, deep green 

 and shining, strongly sagittate, resembling narrow-leaved 

 forms of 8. latifolia Willd.j basal lobes 2 to 3 dm. 



of 8. latifolia Willd. ; 



long, long acuminate, pointing downwards, the middle lobe 

 2 to 2.5 dm. long, also acuminate, pointing upwards ; scape 

 tall, stout and robust, 4- to 6-angled, the larger often 25 

 mm. thick, noticeably taller and stouter than that of 8. 

 latifolia, with which it is associated, often 8 dm. tall, and 

 exceeding the leaves ; bracts separate or very slightly united 

 at base, lanceolate, tapering to a long acumination, espe- 

 cially the lower ones, the acumination of which is some- 



times 



pedicels in length 



reflexed in age; whorls of the inflorescence numerous, 

 usually branching below, the lower ones bearing pistillate, 

 the upper ones staminate, flowers; pedicels straight, the 

 fertile ones usuallv 2 cm. or less long, those bearing the 



staminate flowers a little longer; flowers barely 25 mm. 

 across, with spreading white petals; sepals about 10 



mm 



long, ovate, obtuse; filaments glabrous; mature fruiting 

 heads depressed-globose, 2 to 3 cm. in diameter; achenes 

 about 2.5 mm. long, obovate-cuneate to nearly square, 



ma i 



extending above the body of the achene ; beak erect, lat- 

 eral, minute, .5 mm. or less long. — In shallow sloughs alono- 



the Missouri River bottoms, 

 and autumn. 



Mi 



S 



Readily distinguished from all forms of 8. latifolia by 

 the minute erect beak of the achene, 8. latifolia having a 



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