2OO 



Minnesota Plant Life. 



as must often have been observed by every one who has fished 

 in Minnesota lakes. 



The different species of pondweeds may be distinguished 

 by their leaves. In one common variety leaves of a somewhat 

 oval shape float upon the surface of the water, but besides these 

 there are present upon the submerged portions of the plant 

 short, reduced, grass-like leaves. In another with leaves some- 

 what similar, but crowded together and altogether submerged, 

 there w r ill not be found the special grass-like leaves. Still an- 

 other has clearly two very different sorts of leaves, some finely 

 dissected and others elliptical in outline. In yet another the 



leaves are all delicate and thread- 

 like. A great variety in the 

 shape and size of pondweed 

 leaves may be observed upon 

 looking down through the clear 

 water upon s u b me r g e cl bars 

 where they grow so luxuriantly. 



In all these plants the seeds 

 are curved or straight and the 

 embryo has no encasement of al- 

 bumen. The fruit, in which are 

 the seeds, consists of four little 

 bodies much like diminutive 

 peaches. Very closely related to 



FIG. 78. Clasping-leaved pondweed. After the pondweeds are the naiads 

 Britton and Brown. ". i- -111 



which may be distinguished by 



the solitary pistil which forms the fruit. They grow in exactly 

 similar localities and one species is common in Minnesota. 



Arrow-grasses. A third family is known as the arrow-grasses. 

 Four species are described from Minnesota localities and are 

 to be found in some abundance in tamarack swamps, especially 

 in the northern part of the state. The leaves are rush-like and 

 the flowers, arranged in terminal, loose spikes, produce stamens 

 and pistils upon the same axis, while from three to six carpels 

 fuse together to make the fruit. One variety of arrow-grass is 

 discriminated by the small number of flowers in the spike. All 

 of these plants are perennial and some of them are to be pretty 

 generally met with in all portions of the state, while others are 



