CONTRIBUTIONS TO THE FLORA OF IOWA. ig 



confined to the hot and dry regions extending west of the Mississip- 

 pi," and it is stated that "Lawrence, Kansas, seems to be about its 

 northern boundary." It is, however, plentiful in Enimett County 

 of this state, fully 300 miles further northward. 



Artemisia annua, L. Leaves twice piunatifid, glabrous ; divisions of the 



lower leaves lanceolate, incised, of the upper linear, pectinately pinnatifid ; 

 flowers panicled, globose, nodding. Northern Persia, Siberia, and China. 



Linnceus' Syst. Veg., 16th ed., cur. Sprengel. 



This was probably first brought to Keokuk as a cultivated plant, 

 but has become a common weed. 



EcHiNOSPERMUM Redowskii, Lelim., var. occidentale, Watson. The 



American plant is less strict, at length diffuse, and the tubercles or scabrosi- 

 ties of the nutlet are sharp instead of blunt or roundish as in the Asiatic 

 plant. Plains. Saskatchewan and Minnesota to Texas, and west to Arizo- 

 na and Alaska. Gray's Synop. Fl. N. Amer., 190. 



The typical form of this species is a native of Northern Asia. 



PoTAMOGETON Illinoensis, MoroiiQ. Floating leaves opposite, thick, 



coriaceous, oval or ovate, 2-3 inches long by \% broad, 19-23 nerved, on 

 short petioles, submerged leaves comparatively few, oblong-elliptical, acute 

 at each end, usually ample (the largest nearly 8 inches long and l^j wide), 

 nearly or quite sessile, the uppermost opposite ; stipules free, obtuse, strong- 

 ly bicarinate, about 2 inches long; peduncles often clustered at the summit 

 of the stem ; spikes about 2 inches long, densely flowered ; fruit roundish ob- 

 ovate, 3 -keeled on the back, the middle keel prominent, and sometimes 

 shouldered at the top, flattened and slightly impressed on the sides, obtuse 



or occasionally pointed at the base, the style short and nearly facial. xU- 



lied to P. lucens, L. in habit, but with larger fruit, and in foliage quite dis- 

 tinct. Mississippi River bottoms near Oquawka, 111., Englewood, 111. Bot. 

 Gazette, F, 50, 1880. 



Sagittaria cristata, Engelm. iiied. Flowers ouly of the lowest 



whorl fertile; fruit-heads much larger than in H. graminea; achenia broad, 



with a conspicuous horizontal style, and crested back and sides. Dr. 



Engelmann adds that this is near S. graminen, Michx., and is perhaps only 

 a variety of it, although the only other Sagittaria with such crests to the 

 achenia is *S'. natans, Michx. Further observations are needed to eventually 

 place it correctly. Letter dated March loth, 1882. 



Beckmannia, Host. Panicle racemose, contracted ; spikelets com- 

 pressed, 2-flowered, the upper floret an abortive rudiment; glumes obovate, 

 compressed boat-shaped, equal, a little shorter than the flower, pointless; 

 palets membranous, the lower ovate, mucronate, 3 -nerved, the upper 

 2-nerved, bifld ; grain free. 



B. eruc^formis. Host. Culms stout, 1-3^^ feet high, with the sheaths 



glabrous ; ligules elongated ; leaves linear, 4-8 inches long, flat, scabrous ; 

 panicle 4-12 inches long, erect, strict, secund, the short crowded branches 



