GRAMINEAE 11 



1. S. latifolia Willd. Scape 3^-4° higb : filaments glabrous : achene 

 about 1^^ long, winged on both margins with a long horizontal beak ; 

 leaves in our plant usually large and broad. — Common throughout in 

 ponds and along streams. June-October. 



2. S. rigida Pursh. Scape weak, shorter than the leaves, the latter 

 lance-oval, entire or with one or two basal lobes : fertile flowers sessile : 

 pedicels of sterile flowers V or less long : filaments glandular-pubescent : 

 achenes long-beaked. — Common in ponds at Lake City, Sheflield, and 

 Atherton. June-September. 



3. S. graminea Michx. 1° high : leaves long-petioled, often blade- 

 less : flowers all pedicelled : filaments pubescent: achene less than V^ 

 long, slightly winged, short-beaked. — Common in ponds at Lake City, 

 Sheflield, and Atherton. June-September. 



Family 12. VALLISNERIACEAE Dumort. 

 Aquatic herbs with regular dioecious flowers from a spathe. Perianth 

 segments in fertile flowers adherent at base to ovary. Ovary 1-celled 

 with three parietal placentae. Indehiscent fruit ripening under water. 



1. PHILOTRIA Eaf. 



Branching very leafy stems submersed. Leaves 1-nerved, sessile, 

 pedicelled. Flowers sessile, from a 2-cleft spathe. Perianth segments 

 six. Sterile flowers minute, with 9 stamens, breaking off and floating on 

 the surface of the water. Pistillate flowers with a very long capillary 

 tube, floating. Stigmas 3, two-lobed. 



1. P. Canadensis (Michx.) Britton. Water- weed. Leaves 2^^- 7^^ 

 long, opposite or verticillate, serrulate. — In Fish Lake and in ponds 

 along the Little Blue north of Glendale. June. 



Family 13. GRAMINEAE Juss. 

 A large and very important order of herbaceous plants with (usually) 

 hollow stems closed at the joints. Leaves sheathing. Inflorescence very 

 varied, consisting of spikelets formed of flowers solitary in the axils of 

 two-ranked scales, called glumes. Lower glumes empty. Upper glumes 

 containing flowers which are usually enveloped in a thin scale, called the 

 palet. Flowers perfect or imperfect. Stamens usually three. Ovary 

 one-celled, one-ovuled. Styles two. Fruit a seed-like grain. 



I. 



Spikelets 1-2-flowered. Rachis articulated 

 below the glumes, so that the spikelets 

 break off as a whole. 

 Flowers monoecious. 



Fertile spikelets imbedded in the thick 



rachis. 1. Tripsacum. 



P^lowers panicled, pedicelled. 11. Zizania. 



